PsychError SCREENPutImage(void) 
{
	PsychRectType 		windowRect,positionRect;
	int 			ix, iy, numPlanes, bitsPerColor, matrixRedIndex, matrixGreenIndex, matrixBlueIndex, matrixAlphaIndex, matrixGrayIndex;
	int 			inputM, inputN, inputP, positionRectWidth, positionRectHeight; 
	PsychWindowRecordType	*windowRecord;
	unsigned char		*inputMatrixByte;
	double			*inputMatrixDouble;
	GLuint			*compactMat, matrixGrayValue, matrixRedValue, matrixGreenValue, matrixBlueValue, matrixAlphaValue, compactPixelValue;
	PsychArgFormatType	inputMatrixType;
	GLfloat			xZoom=1, yZoom=-1;
        
	//all sub functions should have these two lines
	PsychPushHelp(useString, synopsisString, seeAlsoString);
	if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};

	//cap the number of inputs
	PsychErrorExit(PsychCapNumInputArgs(4));   //The maximum number of inputs
	PsychErrorExit(PsychCapNumOutputArgs(0));  //The maximum number of outputs
        
        //get the image matrix
        inputMatrixType=PsychGetArgType(2);
        switch(inputMatrixType){
            case PsychArgType_none : case PsychArgType_default:
                PsychErrorExitMsg(PsychError_user, "imageArray argument required");
                break;
            case PsychArgType_uint8 :
                PsychAllocInUnsignedByteMatArg(2, TRUE, &inputM, &inputN, &inputP, &inputMatrixByte);
                break;
            case PsychArgType_double :
                PsychAllocInDoubleMatArg(2, TRUE, &inputM, &inputN, &inputP, &inputMatrixDouble);
                break;
            default :
                PsychErrorExitMsg(PsychError_user, "imageArray must be uint8 or double type");
                break;
        }
        
        //get the window and get the rect and stuff
        PsychAllocInWindowRecordArg(kPsychUseDefaultArgPosition, TRUE, &windowRecord);
        numPlanes=PsychGetNumPlanesFromWindowRecord(windowRecord);
        bitsPerColor=PsychGetColorSizeFromWindowRecord(windowRecord);
        PsychGetRectFromWindowRecord(windowRect, windowRecord);
	if(PsychCopyInRectArg(3, FALSE, positionRect)){
            positionRectWidth=(int)PsychGetWidthFromRect(positionRect);
            positionRectHeight=(int)PsychGetHeightFromRect(positionRect);
            if(inputP != 1 && inputP != 3 && inputP != 4)
                PsychErrorExitMsg(PsychError_user, "Third dimension of image matrix must be 1, 3, or 4"); 
            if( positionRectWidth != inputN  || positionRectHeight != inputM){
                //calculate the zoom factor
                xZoom=(GLfloat)positionRectWidth/(GLfloat)inputN;
                yZoom=-((GLfloat)positionRectHeight/(GLfloat)inputM);
            }
        }else{
           positionRect[kPsychLeft]=0;
           positionRect[kPsychTop]=0;
           positionRect[kPsychRight]=inputN;
           positionRect[kPsychBottom]=inputM;
           PsychCenterRect(positionRect, windowRect, positionRect);
           //This should be centered  
        }
        
        
        //put up the image
        if(numPlanes==1){  //screen planes, not image matrix planes.  
            PsychErrorExitMsg(PsychError_unimplemented, "Put Image does not yet support indexed mode");
            //remember to test here for inputP==3 because that would be wrong. 
        }else if(numPlanes==4){
            compactMat=(GLuint *)mxMalloc(sizeof(GLuint) * inputN * inputM);
            for(ix=0;ix<inputN;ix++){
                for(iy=0;iy<inputM;iy++){
                    if(inputP==1){
                        matrixGrayIndex=PsychIndexElementFrom3DArray(inputM, inputN, 1, iy, ix, 0);
                        if(inputMatrixType==PsychArgType_uint8)
                            matrixGrayValue=(GLuint)inputMatrixByte[matrixGrayIndex];
                        else //inputMatrixType==PsychArgType_double
                            matrixGrayValue=(GLuint)inputMatrixDouble[matrixGrayIndex];
                
                        compactPixelValue=((matrixGrayValue<<8 | matrixGrayValue)<<8 | matrixGrayValue)<<8 | 255; 
                        compactMat[iy*inputN+ix]=compactPixelValue; 
                    }else if(inputP==3){
                        matrixRedIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 0);
                        matrixGreenIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 1);
                        matrixBlueIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 2);
                        if(inputMatrixType==PsychArgType_uint8){
                            matrixRedValue=(GLuint)inputMatrixByte[matrixRedIndex];
                            matrixGreenValue=(GLuint)inputMatrixByte[matrixGreenIndex];
                            matrixBlueValue=(GLuint)inputMatrixByte[matrixBlueIndex];
                            matrixAlphaValue=(GLuint)255;
                        }else{
                            matrixRedValue=(GLuint)inputMatrixDouble[matrixRedIndex];
                            matrixGreenValue=(GLuint)inputMatrixDouble[matrixGreenIndex];
                            matrixBlueValue=(GLuint)inputMatrixDouble[matrixBlueIndex];
                            matrixAlphaValue=(GLuint)255;
                        }
                        compactPixelValue= ((matrixRedValue<<8 | matrixGreenValue )<<8 | matrixBlueValue)<<8 | matrixAlphaValue; 
                        compactMat[iy*inputN+ix]=compactPixelValue; 
                    }else if(inputP==4){
                        matrixRedIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 0);
                        matrixGreenIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 1);
                        matrixBlueIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 2);
                        matrixAlphaIndex=PsychIndexElementFrom3DArray(inputM, inputN, 3, iy, ix, 3);
                        if(inputMatrixType==PsychArgType_uint8){  
                            matrixRedValue=(GLuint)inputMatrixByte[matrixRedIndex];
                            matrixGreenValue=(GLuint)inputMatrixByte[matrixGreenIndex];
                            matrixBlueValue=(GLuint)inputMatrixByte[matrixBlueIndex];
                            matrixAlphaValue=(GLuint)inputMatrixByte[matrixAlphaIndex];
                        }else{
                            matrixRedValue=(GLuint)inputMatrixDouble[matrixRedIndex];
                            matrixGreenValue=(GLuint)inputMatrixDouble[matrixGreenIndex];
                            matrixBlueValue=(GLuint)inputMatrixDouble[matrixBlueIndex];
                            matrixAlphaValue=(GLuint)inputMatrixDouble[matrixAlphaIndex];
                        }
                        compactPixelValue= ((matrixRedValue<<8 | matrixGreenValue )<<8 | matrixBlueValue)<<8 | matrixAlphaValue; 
                        compactMat[iy*inputN+ix]=compactPixelValue; 

                    }

                 }
            }

            PsychSetGLContext(windowRecord);
			PsychUpdateAlphaBlendingFactorLazily(windowRecord);

            glRasterPos2i((GLint)(positionRect[kPsychLeft]), (GLint)(positionRect[kPsychTop]));
            PsychTestForGLErrors();
            glPixelStorei(GL_UNPACK_ALIGNMENT, (GLint)(sizeof(GLuint)));  //4  
            PsychTestForGLErrors();
            glPixelZoom(xZoom,yZoom);
            PsychTestForGLErrors();            
            glDrawPixels(inputN, inputM, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, compactMat);
            free((void *)compactMat);
            PsychTestForGLErrors();
            PsychFlushGL(windowRecord);  //OS X: This does nothing if we are multi buffered, otherwise it glFlushes
						
			
            PsychTestForGLErrors();
        }else if(numPlanes==3)
            PsychErrorExitMsg(PsychError_unimplemented, "PutImage found hardware without an alpha channel.");	

	return(PsychError_none);
}
PsychError SCREENGetImage(void) 
{
	PsychRectType   windowRect,sampleRect;
	int 			nrchannels, ix, iy, sampleRectWidth, sampleRectHeight, invertedY, redReturnIndex, greenReturnIndex, blueReturnIndex, alphaReturnIndex, planeSize;
	int				viewid;
	ubyte 			*returnArrayBase, *redPlane, *greenPlane, *bluePlane, *alphaPlane;
	float 			*dredPlane, *dgreenPlane, *dbluePlane, *dalphaPlane;
	double 			*returnArrayBaseDouble;
	PsychWindowRecordType	*windowRecord;
	GLboolean		isDoubleBuffer, isStereo;
	char*           buffername = NULL;
	boolean			floatprecision = FALSE;
	GLenum			whichBuffer = 0; 
	
	//all sub functions should have these two lines
	PsychPushHelp(useString, synopsisString, seeAlsoString);
	if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};
	
	//cap the numbers of inputs and outputs
	PsychErrorExit(PsychCapNumInputArgs(5));   //The maximum number of inputs
	PsychErrorExit(PsychCapNumOutputArgs(1));  //The maximum number of outputs
	
	// Get windowRecord for this window:
	PsychAllocInWindowRecordArg(kPsychUseDefaultArgPosition, TRUE, &windowRecord);
	
	// Set window as drawingtarget: Even important if this binding is changed later on!
	// We need to make sure all needed transitions are done - esp. in non-imaging mode,
	// so backbuffer is in a useable state:
	PsychSetDrawingTarget(windowRecord);
	
	// Disable shaders:
	PsychSetShader(windowRecord, 0);

	// Soft-Reset drawingtarget. This is important to make sure no FBO's are bound,
	// otherwise the following glGets for GL_DOUBLEBUFFER and GL_STEREO will retrieve
	// wrong results, leading to totally wrong read buffer assignments down the road!!
	PsychSetDrawingTarget(0x1);

	glGetBooleanv(GL_DOUBLEBUFFER, &isDoubleBuffer);
	glGetBooleanv(GL_STEREO, &isStereo);
	
	// Retrieve optional read rectangle:
	PsychGetRectFromWindowRecord(windowRect, windowRecord);
	if(!PsychCopyInRectArg(2, FALSE, sampleRect)) memcpy(sampleRect, windowRect, sizeof(PsychRectType));
	if (IsPsychRectEmpty(sampleRect)) return(PsychError_none);
	
	// Assign read buffer:
	if(PsychIsOnscreenWindow(windowRecord)) {
		// Onscreen window: We read from the front- or front-left buffer by default.
		// This works on single-buffered and double buffered contexts in a consistent fashion:
		
		// Copy in optional override buffer name:
		PsychAllocInCharArg(3, FALSE, &buffername);
		
		// Override buffer name provided?
		if (buffername) {
			// Which one is it?
			
			// "frontBuffer" is always a valid choice:
			if (PsychMatch(buffername, "frontBuffer")) whichBuffer = GL_FRONT;
			// Allow selection of left- or right front stereo buffer in stereo mode:
			if (PsychMatch(buffername, "frontLeftBuffer") && isStereo) whichBuffer = GL_FRONT_LEFT;
			if (PsychMatch(buffername, "frontRightBuffer") && isStereo) whichBuffer = GL_FRONT_RIGHT;
			// Allow selection of backbuffer in double-buffered mode:
			if (PsychMatch(buffername, "backBuffer") && isDoubleBuffer) whichBuffer = GL_BACK;
			// Allow selection of left- or right back stereo buffer in stereo mode:
			if (PsychMatch(buffername, "backLeftBuffer") && isStereo && isDoubleBuffer) whichBuffer = GL_BACK_LEFT;
			if (PsychMatch(buffername, "backRightBuffer") && isStereo && isDoubleBuffer) whichBuffer = GL_BACK_RIGHT;
			// Allow AUX buffer access for debug purposes:
			if (PsychMatch(buffername, "aux0Buffer")) whichBuffer = GL_AUX0;
			if (PsychMatch(buffername, "aux1Buffer")) whichBuffer = GL_AUX1;
			if (PsychMatch(buffername, "aux2Buffer")) whichBuffer = GL_AUX2;
			if (PsychMatch(buffername, "aux3Buffer")) whichBuffer = GL_AUX3;			
		}
		else {
			// Default is frontbuffer:
			whichBuffer=GL_FRONT;
		}
	}
	else {
		// Offscreen window or texture: They only have one buffer, which is the
		// backbuffer in double-buffered mode and the frontbuffer in single buffered mode:
		whichBuffer=(isDoubleBuffer) ? GL_BACK : GL_FRONT;
	}
	
	// Enable this windowRecords framebuffer as current drawingtarget. This should
	// also allow us to "GetImage" from Offscreen windows:
	if ((windowRecord->imagingMode & kPsychNeedFastBackingStore) || (windowRecord->imagingMode & kPsychNeedFastOffscreenWindows)) {
		// Special case: Imaging pipeline active - We need to activate system framebuffer
		// so we really read the content of the framebuffer and not of some FBO:
		if (PsychIsOnscreenWindow(windowRecord)) {
			// It's an onscreen window:
			if (buffername && (PsychMatch(buffername, "drawBuffer")) && (windowRecord->imagingMode & kPsychNeedFastBackingStore)) {
				// Activate drawBufferFBO:
				PsychSetDrawingTarget(windowRecord);
				whichBuffer = GL_COLOR_ATTACHMENT0_EXT;
				
				// Is the drawBufferFBO multisampled?
				viewid = (((windowRecord->stereomode > 0) && (windowRecord->stereodrawbuffer == 1)) ? 1 : 0);
				if (windowRecord->fboTable[windowRecord->drawBufferFBO[viewid]]->multisample > 0) {
					// It is! We can't read from a multisampled FBO. Need to perform a multisample resolve operation and read
					// from the resolved unisample buffer instead. This is only safe if the unisample buffer is either a dedicated
					// FBO, or - in case its the final system backbuffer etc. - if preflip operations haven't been performed yet.
					// If non dedicated buffer (aka finalizedFBO) and preflip ops have already happened, then the backbuffer contains
					// final content for an upcoming Screen('Flip') and we can't use (and therefore taint) that buffer.
					if ((windowRecord->inputBufferFBO[viewid] == windowRecord->finalizedFBO[viewid]) && (windowRecord->backBufferBackupDone)) {
						// Target for resolve is finalized FBO (probably system backbuffer) and preflip ops have run already. We
						// can't do the resolve op, as this would screw up the backbuffer with the final stimulus:
						printf("PTB-ERROR: Tried to 'GetImage' from a multisampled 'drawBuffer', but can't perform anti-aliasing pass due to\n");
						printf("PTB-ERROR: lack of a dedicated resolve buffer.\n");
						printf("PTB-ERROR: You can get what you wanted by either one of two options:\n");
						printf("PTB-ERROR: Either enable a processing stage in the imaging pipeline, even if you don't need it, e.g., by setting\n");
						printf("PTB-ERROR: the imagingmode argument in the 'OpenWindow' call to kPsychNeedImageProcessing, this will create a\n");
						printf("PTB-ERROR: suitable resolve buffer. Or place the 'GetImage' call before any Screen('DrawingFinished') call, then\n");
						printf("PTB-ERROR: i can (ab-)use the system backbuffer as a temporary resolve buffer.\n\n");
						PsychErrorExitMsg(PsychError_user, "Tried to 'GetImage' from a multi-sampled 'drawBuffer'. Unsupported operation under given conditions.");						
					}
					else {
						// Ok, the inputBufferFBO is a suitable temporary resolve buffer. Perform a multisample resolve blit to it:
						// A simple glBlitFramebufferEXT() call will do the copy & downsample operation:
						glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->drawBufferFBO[viewid]]->fboid);
						glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->fboid);
						glBlitFramebufferEXT(0, 0, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->width, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->height,
											 0, 0, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->width, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->height,
											 GL_COLOR_BUFFER_BIT, GL_NEAREST);

						// Bind inputBuffer as framebuffer:
						glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->fboid);
						viewid = -1;
					}
				}
			}
			else {
				// Activate system framebuffer:
				PsychSetDrawingTarget(NULL);
			}
		}
		else {
			// Offscreen window or texture: Select drawing target as usual,
			// but set color attachment as read buffer:
			PsychSetDrawingTarget(windowRecord);
			whichBuffer = GL_COLOR_ATTACHMENT0_EXT;

			// We do not support multisampled readout:
			if (windowRecord->fboTable[windowRecord->drawBufferFBO[0]]->multisample > 0) {
				printf("PTB-ERROR: You tried to Screen('GetImage', ...); from an offscreen window or texture which has multisample anti-aliasing enabled.\n");
				printf("PTB-ERROR: This operation is not supported. You must first use Screen('CopyWindow') to create a non-multisampled copy of the\n");
				printf("PTB-ERROR: texture or offscreen window, then use 'GetImage' on that copy. The copy will be anti-aliased, so you'll get what you\n");
				printf("PTB-ERROR: wanted with a bit more effort. Sorry for the inconvenience, but this is mostly a hardware limitation.\n\n");
				
				PsychErrorExitMsg(PsychError_user, "Tried to 'GetImage' from a multi-sampled texture or offscreen window. Unsupported operation.");
			}
		}
	}
	else {
		// Normal case: No FBO based imaging - Select drawing target as usual:
		PsychSetDrawingTarget(windowRecord);
	}
	
	// Select requested read buffer, after some double-check:
	if (whichBuffer == 0) PsychErrorExitMsg(PsychError_user, "Invalid or unknown 'bufferName' argument provided.");
	glReadBuffer(whichBuffer);
	
	if (PsychPrefStateGet_Verbosity() > 5) printf("PTB-DEBUG: In Screen('GetImage'): GL-Readbuffer whichBuffer = %i\n", whichBuffer);

	// Get optional floatprecision flag: We return data with float-precision if
	// this flag is set. By default we return uint8 data:
	PsychCopyInFlagArg(4, FALSE, &floatprecision);
	
	// Get the optional number of channels flag: By default we return 3 channels,
	// the Red, Green, and blue color channel:
	nrchannels = 3;
	PsychCopyInIntegerArg(5, FALSE, &nrchannels);
	if (nrchannels < 1 || nrchannels > 4) PsychErrorExitMsg(PsychError_user, "Number of requested channels 'nrchannels' must be between 1 and 4!");
	
	sampleRectWidth=PsychGetWidthFromRect(sampleRect);
	sampleRectHeight=PsychGetHeightFromRect(sampleRect);
	
	if (!floatprecision) {
		// Readback of standard 8bpc uint8 pixels:  
		PsychAllocOutUnsignedByteMatArg(1, TRUE, sampleRectHeight, sampleRectWidth, nrchannels, &returnArrayBase);
		redPlane= PsychMallocTemp(nrchannels * sizeof(GL_UNSIGNED_BYTE) * sampleRectWidth * sampleRectHeight);
		planeSize=sampleRectWidth * sampleRectHeight;
		greenPlane= redPlane + planeSize;
		bluePlane= redPlane + 2 * planeSize;
		alphaPlane= redPlane + 3 * planeSize; 
		glPixelStorei(GL_PACK_ALIGNMENT,1);
		invertedY=windowRect[kPsychBottom]-sampleRect[kPsychBottom];
		glReadPixels(sampleRect[kPsychLeft],invertedY, 	sampleRectWidth, sampleRectHeight, GL_RED, GL_UNSIGNED_BYTE, redPlane); 
		if (nrchannels>1) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_GREEN, GL_UNSIGNED_BYTE, greenPlane);
		if (nrchannels>2) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_BLUE, GL_UNSIGNED_BYTE, bluePlane);
		if (nrchannels>3) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_ALPHA, GL_UNSIGNED_BYTE, alphaPlane);
		
		//in one pass transpose and flip what we read with glReadPixels before returning.  
		//-glReadPixels insists on filling up memory in sequence by reading the screen row-wise whearas Matlab reads up memory into columns.
		//-the Psychtoolbox screen as setup by gluOrtho puts 0,0 at the top left of the window but glReadPixels always believes that it's at the bottom left.     
		for(ix=0;ix<sampleRectWidth;ix++){
			for(iy=0;iy<sampleRectHeight;iy++){
				// Compute write-indices for returned data:
				redReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, nrchannels, iy, ix, 0);
				greenReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 1);
				blueReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 2);
				alphaReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 3);
				
				// Always return RED/LUMINANCE channel:
				returnArrayBase[redReturnIndex]=redPlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];  
				// Other channels on demand:
				if (nrchannels>1) returnArrayBase[greenReturnIndex]=greenPlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];
				if (nrchannels>2) returnArrayBase[blueReturnIndex]=bluePlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];
				if (nrchannels>3) returnArrayBase[alphaReturnIndex]=alphaPlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];
			}
		}		
	}
	else {
		// Readback of standard 32bpc float pixels into a double matrix:  
		PsychAllocOutDoubleMatArg(1, TRUE, sampleRectHeight, sampleRectWidth, nrchannels, &returnArrayBaseDouble);
		dredPlane= PsychMallocTemp(nrchannels * sizeof(GL_FLOAT) * sampleRectWidth * sampleRectHeight);
		planeSize=sampleRectWidth * sampleRectHeight * sizeof(GL_FLOAT);
		dgreenPlane= redPlane + planeSize;
		dbluePlane= redPlane + 2 * planeSize;
		dalphaPlane= redPlane + 3 * planeSize; 
		glPixelStorei(GL_PACK_ALIGNMENT, 1);
		invertedY=windowRect[kPsychBottom]-sampleRect[kPsychBottom];
		if (nrchannels==1) glReadPixels(sampleRect[kPsychLeft],invertedY, 	sampleRectWidth, sampleRectHeight, GL_RED, GL_FLOAT, dredPlane); 
		if (nrchannels==2) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_LUMINANCE_ALPHA, GL_FLOAT, dredPlane);
		if (nrchannels==3) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_RGB, GL_FLOAT, dredPlane);
		if (nrchannels==4) glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_RGBA, GL_FLOAT, dredPlane);
		
		//in one pass transpose and flip what we read with glReadPixels before returning.  
		//-glReadPixels insists on filling up memory in sequence by reading the screen row-wise whearas Matlab reads up memory into columns.
		//-the Psychtoolbox screen as setup by gluOrtho puts 0,0 at the top left of the window but glReadPixels always believes that it's at the bottom left.     
		for(ix=0;ix<sampleRectWidth;ix++){
			for(iy=0;iy<sampleRectHeight;iy++){
				// Compute write-indices for returned data:
				redReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, nrchannels, iy, ix, 0);
				greenReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 1);
				blueReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 2);
				alphaReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 3);
				
				// Always return RED/LUMINANCE channel:
				returnArrayBaseDouble[redReturnIndex]=dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * nrchannels + 0];  
				// Other channels on demand:
				if (nrchannels>1) returnArrayBaseDouble[greenReturnIndex]=dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * nrchannels + 1];
				if (nrchannels>2) returnArrayBaseDouble[blueReturnIndex]=dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * nrchannels + 2];
				if (nrchannels>3) returnArrayBaseDouble[alphaReturnIndex]=dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * nrchannels + 3];
			}
		}		
	}
	
	if (viewid == -1) {
		// Need to reset framebuffer binding to get rid of the inputBufferFBO which is bound due to
		// multisample resolve ops --> Activate system framebuffer:
		PsychSetDrawingTarget(NULL);		
	}

	return(PsychError_none);
}
PsychError SCREENGetImage(void) 
{
	PsychRectType 		windowRect,sampleRect;
        int 			ix, iy, numPlanes, bitsPerColor, sampleRectWidth, sampleRectHeight, invertedY, redReturnIndex, greenReturnIndex, blueReturnIndex, planeSize;
        ubyte 			*returnArrayBase, *redPlane, *greenPlane, *bluePlane;
        PsychWindowRecordType	*windowRecord;
        //char 			*bufferFlagNames[] = {"frontBuffer", "backBuffer", NULL};
        GLenum			whichBuffer; 
        //GLenum		glBuffers[] = {GL_FRONT, GL_BACK, NULL};
        GLboolean		isDoubleBuffer;
        
        
	//all sub functions should have these two lines
	PsychPushHelp(useString, synopsisString, seeAlsoString);
	if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};

	//cap the numbers of inputs and outputs
	PsychErrorExit(PsychCapNumInputArgs(2));   //The maximum number of inputs
	PsychErrorExit(PsychCapNumOutputArgs(1));  //The maximum number of outputs
        
        glGetBooleanv(GL_DOUBLEBUFFER, &isDoubleBuffer);
	
        PsychAllocInWindowRecordArg(kPsychUseDefaultArgPosition, TRUE, &windowRecord);
        PsychSetGLContext(windowRecord);
        numPlanes=PsychGetNumPlanesFromWindowRecord(windowRecord);
        bitsPerColor=PsychGetColorSizeFromWindowRecord(windowRecord);
        PsychGetRectFromWindowRecord(windowRect, windowRecord);
	if(!PsychCopyInRectArg(2, FALSE, sampleRect))
            memcpy(sampleRect, windowRect, sizeof(PsychRectType));
        whichBuffer=GL_FRONT; 
        //glReadBuffer(whichBuffer);
        
        //PsychCopyInNamedFlagIndexArg(3, FALSE, bufferFlagNames, bufferFlagIndices, &whichBuffer);  //not yet implemented.  
        sampleRectWidth=PsychGetWidthFromRect(sampleRect);
        sampleRectHeight=PsychGetHeightFromRect(sampleRect);
        
        if(numPlanes==1)
            PsychErrorExitMsg(PsychError_unimplemented, "GetImage does not yet support indexed mode");
        else if(numPlanes==3 || numPlanes==4){
            //Note this will only work correctly for 8-bit pixels.  
            if(PsychAllocOutUnsignedByteMatArg(1, TRUE, sampleRectHeight, sampleRectWidth, 3, &returnArrayBase)){
                /*
                redPlaneReturn=returnArrayBase + PsychIndexPlaneFrom3DArray(sampleRectHeight, sampleRectWidth, 3, 0);
                greenPlaneReturn=returnArrayBase + PsychIndexPlaneFrom3DArray(sampleRectHeight, sampleRectWidth, 3, 1);
                bluePlaneReturn=returnArrayBase + PsychIndexPlaneFrom3DArray(sampleRectHeight, sampleRectWidth, 3, 2);
                */
                redPlane= mxMalloc(3 * sizeof(GL_UNSIGNED_BYTE) * sampleRectWidth * sampleRectHeight);
                planeSize=sampleRectWidth * sampleRectHeight;
                greenPlane= redPlane + planeSize;
                bluePlane= redPlane + 2 * planeSize;
                glPixelStorei(GL_PACK_ALIGNMENT,1);
                invertedY=windowRect[kPsychBottom]-sampleRect[kPsychBottom];
                glReadPixels(sampleRect[kPsychLeft],invertedY, 	sampleRectWidth, sampleRectHeight, GL_RED, GL_UNSIGNED_BYTE, redPlane); 
                glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_GREEN, GL_UNSIGNED_BYTE, greenPlane);
                glReadPixels(sampleRect[kPsychLeft],invertedY,	sampleRectWidth, sampleRectHeight, GL_BLUE, GL_UNSIGNED_BYTE, bluePlane);
                //in one pass transpose and flip what we read with glReadPixels before returning.  
                //-glReadPixels insists on filling up memory in sequence by reading the screen row-wise whearas Matlab reads up memory into columns.
                //-the Psychtoolbox screen as setup by gluOrtho puts 0,0 at the top left of the window but glReadPixels always believes that it's at the bottom left.     
                for(ix=0;ix<sampleRectWidth;ix++){
                    for(iy=0;iy<sampleRectHeight;iy++){
                        redReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, 3, iy, ix, 0);
                        greenReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, 3, iy, ix, 1);
                        blueReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, 3, iy, ix, 2);
                        returnArrayBase[redReturnIndex]=redPlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];  
                        returnArrayBase[greenReturnIndex]=greenPlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];
                        returnArrayBase[blueReturnIndex]=bluePlane[ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth];
                    }
                }
            }
        }
        else 
            PsychErrorExitMsg(PsychError_internal, "Unexpected number of color planes");	

	return(PsychError_none);
}
PsychError SCREENReadNormalizedGammaTable(void)
{
    int		i, screenNumber, numEntries, reallutsize, physicalDisplay, outputId;
    float 	*redTable, *greenTable, *blueTable;
    double	*gammaTable;	

    //all subfunctions should have these two lines
    PsychPushHelp(useString, synopsisString, seeAlsoString);
    if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};

    PsychErrorExit(PsychCapNumOutputArgs(3));
    PsychErrorExit(PsychCapNumInputArgs(2));

    // Get optional physicalDisplay argument - It defaults to zero:
    physicalDisplay = -1;
    PsychCopyInIntegerArg(2, FALSE, &physicalDisplay);

    // Read in the screen number:
    // On OS/X we also accept screen indices for physical displays (as opposed to active dispays).
    // This only makes a difference in mirror-mode, where there is only 1 active display, but that
    // corresponds to two physical displays which can have different gamma setting requirements:
    if ((PSYCH_SYSTEM == PSYCH_OSX) && (physicalDisplay > 0)) {
        PsychCopyInIntegerArg(1, TRUE, &screenNumber);
	if (screenNumber < 1) PsychErrorExitMsg(PsychError_user, "A 'screenNumber' that is smaller than one provided, although 'physicalDisplay' flag set. This is not allowed!");

	// Invert screenNumber as a sign its a physical display, not an active display:
	screenNumber = -1 * screenNumber;
    }
    else {
        PsychCopyInScreenNumberArg(1, TRUE, &screenNumber);
    }

    if ((PSYCH_SYSTEM == PSYCH_LINUX) && (physicalDisplay > -1)) {
	// Affect one specific display output for given screen:
	outputId = physicalDisplay;
    }
    else {
	// Other OS'es, and Linux with default setting: Affect all outputs
	// for a screen.
	outputId = -1;
    }

    // Retrieve gamma table:
    PsychReadNormalizedGammaTable(screenNumber, outputId, &numEntries, &redTable, &greenTable, &blueTable);
	
    // Copy it out to runtime:
    PsychAllocOutDoubleMatArg(1, FALSE, numEntries, 3, 0, &gammaTable);

    for(i=0;i<numEntries;i++){
        gammaTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 0, 0)]=(double)redTable[i];
        gammaTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 1, 0)]=(double)greenTable[i];
        gammaTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 2, 0)]=(double)blueTable[i];
    }

    // Copy out optional DAC resolution value:
    PsychCopyOutDoubleArg(2, FALSE, (double) PsychGetDacBitsFromDisplay(screenNumber));
	
    // We default to the assumption that the real size of the hardware LUT is identical to
    // the size of the returned LUT:
    reallutsize = numEntries;
	
    #if PSYCH_SYSTEM == PSYCH_OSX
		// On OS-X we query the real LUT size from the OS and return that value:
		CGDirectDisplayID	displayID;
		CFMutableDictionaryRef properties;
		CFNumberRef cfGammaLength;
		SInt32 lutslotcount;
		io_service_t displayService;
		kern_return_t kr;
		CFMutableArrayRef framebufferTimings0 = 0;
		CFDataRef framebufferTimings1 = 0;
		IODetailedTimingInformationV2 *framebufferTiming = NULL;
		
		// Retrieve display handle for screen:
		PsychGetCGDisplayIDFromScreenNumber(&displayID, screenNumber);
		
		if (PsychPrefStateGet_Verbosity()>5) printf("PTB-DEBUG: Screen %i has framebuffer address %p.\n", screenNumber, CGDisplayBaseAddress(displayID));

		// Retrieve low-level IOKit service port for this display:
		displayService = CGDisplayIOServicePort(displayID);
				
		// Obtain the properties from that service
		kr = IORegistryEntryCreateCFProperties(displayService, &properties, NULL, 0);
		if((kr == kIOReturnSuccess) && ((cfGammaLength = (CFNumberRef) CFDictionaryGetValue(properties, CFSTR(kIOFBGammaCountKey)))!=NULL))
		{
			CFNumberGetValue(cfGammaLength, kCFNumberSInt32Type, &lutslotcount);
			CFRelease(properties);
			reallutsize = (int) lutslotcount;
		}
		else {
			// Failed!
			if (PsychPrefStateGet_Verbosity()>1) printf("PTB-WARNING: Failed to query real size of video LUT for screen %i! Will return safe default of %i slots.\n", screenNumber, reallutsize);
		}	

		if (PsychPrefStateGet_Verbosity()>9) {			
			CFDictionaryRef currentMode;
			CFNumberRef n;
			int modeId;
			currentMode = CGDisplayCurrentMode(displayID);
			n=CFDictionaryGetValue(currentMode, kCGDisplayMode);
			CFNumberGetValue(n, kCFNumberIntType, &modeId);
			printf("Current mode has id %i\n\n", modeId);
			kr = IORegistryEntryCreateCFProperties(displayService, &properties, NULL, 0);
			if((kr == kIOReturnSuccess) && ((framebufferTimings0 = (CFMutableArrayRef) CFDictionaryGetValue(properties, CFSTR(kIOFBDetailedTimingsKey) ) )!=NULL))
			{
				for (i=0; i<CFArrayGetCount(framebufferTimings0); i++) {
					if ((framebufferTimings1 = CFArrayGetValueAtIndex(framebufferTimings0, i)) != NULL) {
						if ((framebufferTiming = (IODetailedTimingInformationV2*) CFDataGetBytePtr(framebufferTimings1)) != NULL) {
							printf("[%i] : VActive =  %li, VBL = %li, VSYNC = %li, VSYNCWIDTH = %li , VBORDERBOT = %li, VTOTAL = %li \n", i, framebufferTiming->verticalActive, framebufferTiming->verticalBlanking, framebufferTiming->verticalSyncOffset, framebufferTiming->verticalSyncPulseWidth, framebufferTiming->verticalBorderBottom, framebufferTiming->verticalActive + framebufferTiming->verticalBlanking);
						}
					}
				}

				CFRelease(properties);
			}
			else {
				// Failed!
				if (PsychPrefStateGet_Verbosity()>1) printf("PTB-WARNING: Failed to query STUFF for screen %i --> %p!\n", screenNumber, properties);
			}	
		}
		


    #endif
	
    // Copy out optional real LUT size (number of slots):
    PsychCopyOutDoubleArg(3, FALSE, (double) reallutsize);

    return(PsychError_none);
}
PsychError SCREENLoadCLUT(void) 
{
    int		i, screenNumber, numEntries, inM, inN, inP, start, bits;
    float 	*outRedTable, *outGreenTable, *outBlueTable, *inRedTable, *inGreenTable, *inBlueTable;
    double	 *inTable, *outTable, maxval;	
    psych_bool     isclutprovided;

    start = 0;
    bits = 8;

    //all subfunctions should have these two lines
    PsychPushHelp(useString, synopsisString, seeAlsoString);
    if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};

    PsychErrorExit(PsychCapNumOutputArgs(1));
    PsychErrorExit(PsychCapNumInputArgs(4));

    // Read in the screen number:
    PsychCopyInScreenNumberArg(1, TRUE, &screenNumber);
    
    // Read in optional start index:
    PsychCopyInIntegerArg(3, FALSE, &start);
    if (start<0 || start>255) {
      PsychErrorExitMsg(PsychError_user, "Argument startEntry must be between zero and 255.");
    }

    // Read in optional bits argument:
    PsychCopyInIntegerArg(4, FALSE, &bits);
    if (bits<1 || bits>16) {
      PsychErrorExitMsg(PsychError_user, "Argument 'bits' must be between 1 and 16.");
    }

    // Compute allowable maxval:
    maxval=(double) ((1 << bits) - 1);

    // First read the existing gamma table so we can return it.  
    PsychReadNormalizedGammaTable(screenNumber, &numEntries, &outRedTable, &outGreenTable, &outBlueTable);

    // Load and sanity check the input matrix, and convert from float to doubles:
    isclutprovided = PsychAllocInDoubleMatArg(2, FALSE, &inM,  &inN, &inP, &inTable);

    if (isclutprovided) {
      if((inM > 256 - start) || (inM < 1) || (inN != 3) || (inP != 1))
        PsychErrorExitMsg(PsychError_user, "The provided CLUT table must have a size between 1 and (256 - startEntry) rows and 3 columns.");
      
      inRedTable=PsychMallocTemp(sizeof(float) * 256);
      inGreenTable=PsychMallocTemp(sizeof(float) * 256);
      inBlueTable=PsychMallocTemp(sizeof(float) * 256);

      // Copy the table into the new inTable array:
      for(i=0; i<numEntries; i++) {
	inRedTable[i] = outRedTable[i];
	inGreenTable[i] = outGreenTable[i];
	inBlueTable[i] = outBlueTable[i];
      }
    }

    // Allocate output array:
    PsychAllocOutDoubleMatArg(1, FALSE, numEntries, 3, 0, &outTable);

    // Copy read table into output array, scale it by maxval to map range 0.0-1.0 to 0-maxval:
    for(i=0;i<numEntries;i++){
      outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 0, 0)]=(double) outRedTable[i] * maxval;
      outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 1, 0)]=(double) outGreenTable[i] * maxval;
      outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 2, 0)]=(double) outBlueTable[i] * maxval;
    }

    if (isclutprovided) {
      // Now we can overwrite entries 'start' to start+inM of inTable with the user provided table values. We
      // need to scale the users values down from 0-maxval to 0.0-1.0:
      for(i=start; (i<256) && (i-start < inM); i++){
	inRedTable[i]   = (float) (inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i-start, 0, 0)] / maxval);
	inGreenTable[i] = (float) (inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i-start, 1, 0)] / maxval);
	inBlueTable[i]  = (float) (inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i-start, 2, 0)] / maxval);
	
	// Range check:
	if(inRedTable[i]>1 || inRedTable[i]< 0 || inGreenTable[i] > 1 || inGreenTable[i] < 0 || inBlueTable[i] >1 || inBlueTable[i] < 0) {
	  printf("PTB-ERROR: At least one of the CLUT values in row %i is outside the valid range of 0 to %i!\n", i-start+1, ((1 << bits) - 1));
	  PsychErrorExitMsg(PsychError_user, "Tried to set a CLUT with invalid entries.");
	}
      }
      
      // Now set the new gamma table
      PsychLoadNormalizedGammaTable(screenNumber, numEntries, inRedTable, inGreenTable, inBlueTable);
    }

    return(PsychError_none);
}
// This also works as 'AddFrameToMovie', as almost all code is shared with 'GetImage'.
// Only difference is where the fetched pixeldata is sent: To the movie encoder or to
// a matlab/octave matrix.
PsychError SCREENGetImage(void) 
{
	PsychRectType   windowRect, sampleRect;
	int 			nrchannels, invertedY, stride;
	size_t			ix, iy, sampleRectWidth, sampleRectHeight, redReturnIndex, greenReturnIndex, blueReturnIndex, alphaReturnIndex, planeSize;
	int				viewid = 0;
	psych_uint8 	*returnArrayBase, *redPlane;
	float 			*dredPlane;
	double 			*returnArrayBaseDouble;
	PsychWindowRecordType	*windowRecord;
	GLboolean		isDoubleBuffer, isStereo;
	char*           buffername = NULL;
	psych_bool		floatprecision = FALSE;
	GLenum			whichBuffer = 0; 
	int				frameduration = 1;
	int				moviehandle = 0;
	unsigned int	twidth, theight, numChannels, bitdepth;
	unsigned char*	framepixels;
	psych_bool      isOES;

	// Called as 2nd personality "AddFrameToMovie" ?
	psych_bool isAddMovieFrame = PsychMatch(PsychGetFunctionName(), "AddFrameToMovie");

	// All sub functions should have these two lines
	if (isAddMovieFrame) {
		PsychPushHelp(useString2, synopsisString2, seeAlsoString);
	}
	else {
		PsychPushHelp(useString, synopsisString, seeAlsoString);
	}
	if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};
	
	//cap the numbers of inputs and outputs
	PsychErrorExit(PsychCapNumInputArgs(5));   //The maximum number of inputs
	PsychErrorExit(PsychCapNumOutputArgs(1));  //The maximum number of outputs
	
	// Get windowRecord for this window:
	PsychAllocInWindowRecordArg(kPsychUseDefaultArgPosition, TRUE, &windowRecord);

    // Embedded subset has very limited support for readback formats :
    isOES = PsychIsGLES(windowRecord);

	// Make sure we don't execute on an onscreen window with pending async flip, as this would interfere
	// by touching the system backbuffer -> Impaired timing of the flip thread and undefined readback
	// of image data due to racing with the ops of the flipperthread on the same drawable.
	//
	// Note: It would be possible to allow drawBuffer readback if the drawBuffer is not multi-sampled
	// or if we can safely multisample-resolve without touching the backbuffer, but checking for all
	// special cases adds ugly complexity and is not really worth the effort, so we don't allow this.
	//
	// If this passes then PsychSetDrawingTarget() below will trigger additional validations to check
	// if execution of 'GetImage' is allowed under the current conditions for offscreen windows and
	// textures:
	if (PsychIsOnscreenWindow(windowRecord) && (windowRecord->flipInfo->asyncstate > 0)) {
		PsychErrorExitMsg(PsychError_user, "Calling this function on an onscreen window with a pending asynchronous flip is not allowed!");
	}

	// Set window as drawingtarget: Even important if this binding is changed later on!
	// We need to make sure all needed transitions are done - esp. in non-imaging mode,
	// so backbuffer is in a useable state:
	PsychSetDrawingTarget(windowRecord);
	
	// Disable shaders:
	PsychSetShader(windowRecord, 0);

	// Soft-Reset drawingtarget. This is important to make sure no FBO's are bound,
	// otherwise the following glGets for GL_DOUBLEBUFFER and GL_STEREO will retrieve
	// wrong results, leading to totally wrong read buffer assignments down the road!!
	PsychSetDrawingTarget((PsychWindowRecordType*) 0x1);

    // Queries only available on desktop OpenGL:
    if (!isOES) {
        glGetBooleanv(GL_DOUBLEBUFFER, &isDoubleBuffer);
        glGetBooleanv(GL_STEREO, &isStereo);
    }
    else {
        // Make something reasonable up:
        isStereo = FALSE;
        isDoubleBuffer = TRUE;
    }

    // Force "quad-buffered" stereo mode if our own homegrown implementation is active:
    if (windowRecord->stereomode == kPsychFrameSequentialStereo) isStereo = TRUE;
    
	// Assign read buffer:
	if(PsychIsOnscreenWindow(windowRecord)) {
		// Onscreen window: We read from the front- or front-left buffer by default.
		// This works on single-buffered and double buffered contexts in a consistent fashion:
		
		// Copy in optional override buffer name:
		PsychAllocInCharArg(3, FALSE, &buffername);
		
		// Override buffer name provided?
		if (buffername) {
			// Which one is it?
			
			// "frontBuffer" is always a valid choice:
			if (PsychMatch(buffername, "frontBuffer")) whichBuffer = GL_FRONT;
			// Allow selection of left- or right front stereo buffer in stereo mode:
			if (PsychMatch(buffername, "frontLeftBuffer") && isStereo) whichBuffer = GL_FRONT_LEFT;
			if (PsychMatch(buffername, "frontRightBuffer") && isStereo) whichBuffer = GL_FRONT_RIGHT;
			// Allow selection of backbuffer in double-buffered mode:
			if (PsychMatch(buffername, "backBuffer") && isDoubleBuffer) whichBuffer = GL_BACK;
			// Allow selection of left- or right back stereo buffer in stereo mode:
			if (PsychMatch(buffername, "backLeftBuffer") && isStereo && isDoubleBuffer) whichBuffer = GL_BACK_LEFT;
			if (PsychMatch(buffername, "backRightBuffer") && isStereo && isDoubleBuffer) whichBuffer = GL_BACK_RIGHT;
			// Allow AUX buffer access for debug purposes:
			if (PsychMatch(buffername, "aux0Buffer")) whichBuffer = GL_AUX0;
			if (PsychMatch(buffername, "aux1Buffer")) whichBuffer = GL_AUX1;
			if (PsychMatch(buffername, "aux2Buffer")) whichBuffer = GL_AUX2;
			if (PsychMatch(buffername, "aux3Buffer")) whichBuffer = GL_AUX3;

            // If 'drawBuffer' is requested, but imaging pipeline inactive, ie., there is no real 'drawBuffer', then we
            // map this to the backbuffer, as on a non-imaging configuration, the backbuffer is pretty much exactly the
            // equivalent of the 'drawBuffer':
            if (PsychMatch(buffername, "drawBuffer") && !(windowRecord->imagingMode & kPsychNeedFastBackingStore)) whichBuffer = GL_BACK;
		}
		else {
			// Default is frontbuffer:
			whichBuffer = GL_FRONT;
		}
	}
	else {
		// Offscreen window or texture: They only have one buffer, which is the
		// backbuffer in double-buffered mode and the frontbuffer in single buffered mode:
		whichBuffer=(isDoubleBuffer) ? GL_BACK : GL_FRONT;
	}
	
	// Enable this windowRecords framebuffer as current drawingtarget. This should
	// also allow us to "GetImage" from Offscreen windows:
	if ((windowRecord->imagingMode & kPsychNeedFastBackingStore) || (windowRecord->imagingMode & kPsychNeedFastOffscreenWindows)) {
		// Special case: Imaging pipeline active - We need to activate system framebuffer
		// so we really read the content of the framebuffer and not of some FBO:
		if (PsychIsOnscreenWindow(windowRecord)) {
			// It's an onscreen window:
            
            // Homegrown frame-sequential stereo active? Need to remap some stuff:
            if (windowRecord->stereomode == kPsychFrameSequentialStereo) {
                // Back/Front buffers map to backleft/frontleft buffers:
                if (whichBuffer == GL_BACK) whichBuffer = GL_BACK_LEFT;
                if (whichBuffer == GL_FRONT) whichBuffer = GL_FRONT_LEFT;
                
                // Special case: Want to read from stereo front buffer?
                if ((whichBuffer == GL_FRONT_LEFT) || (whichBuffer == GL_FRONT_RIGHT)) {
                    // These don't really exist in our homegrown implementation. Their equivalents are the
                    // regular system front/backbuffers. Due to the bufferswaps happening every video
                    // refresh cycle and the complex logic on when and how to blit finalizedFBOs into
                    // the system buffers and the asynchronous execution of the parallel flipper thread,
                    // we don't know which buffer (GL_BACK or GL_FRONT) corresponds to the leftFront or
                    // rightFront buffer. Let's be stupid and just return the current front buffer for
                    // FRONT_LEFT and the current back buffer for FRONT_RIGHT, but warn user about the
                    // ambiguity:
                    whichBuffer = (whichBuffer == GL_FRONT_LEFT) ? GL_FRONT : GL_BACK;
                    
                    if (PsychPrefStateGet_Verbosity() > 2) {
                        printf("PTB-WARNING: In Screen('GetImage'): You selected retrieval of one of the stereo front buffers, while our homegrown frame-sequential\n");
                        printf("PTB-WARNING: In Screen('GetImage'): stereo display mode is active. This will impair presentation timing and may cause flicker. The\n");
                        printf("PTB-WARNING: In Screen('GetImage'): mapping of 'frontLeftBuffer' and 'frontRightBuffer' to actual stimulus content is very ambiguous\n");
                        printf("PTB-WARNING: In Screen('GetImage'): in this mode. You may therefore end up with the content of the wrong buffer returned! Check results\n");
                        printf("PTB-WARNING: In Screen('GetImage'): carefully! Better read from 'backLeftBuffer' or 'backRightBuffer' for well defined results.\n\n");
                    }
                }
            }
            
            // Homegrown frame-sequential stereo active and backleft or backright buffer requested?
            if (((whichBuffer == GL_BACK_LEFT) || (whichBuffer == GL_BACK_RIGHT)) && (windowRecord->stereomode == kPsychFrameSequentialStereo)) {
                // We can get the equivalent of the backLeft/RightBuffer from the finalizedFBO's in this mode. Get their content:                
				viewid = (whichBuffer == GL_BACK_RIGHT) ? 1 : 0;
				whichBuffer = GL_COLOR_ATTACHMENT0_EXT;
                
                // Bind finalizedFBO as framebuffer to read from:
                glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->finalizedFBO[viewid]]->fboid);
                
                // Make sure binding gets released at end of routine:
                viewid = -1;
                
            } // No frame-sequential stereo: Full imaging pipeline active and one of the drawBuffer's requested?
            else if (buffername && (PsychMatch(buffername, "drawBuffer")) && (windowRecord->imagingMode & kPsychNeedFastBackingStore)) {
				// Activate drawBufferFBO:
				PsychSetDrawingTarget(windowRecord);
				whichBuffer = GL_COLOR_ATTACHMENT0_EXT;
				
				// Is the drawBufferFBO multisampled?
				viewid = (((windowRecord->stereomode > 0) && (windowRecord->stereodrawbuffer == 1)) ? 1 : 0);
				if (windowRecord->fboTable[windowRecord->drawBufferFBO[viewid]]->multisample > 0) {
					// It is! We can't read from a multisampled FBO. Need to perform a multisample resolve operation and read
					// from the resolved unisample buffer instead. This is only safe if the unisample buffer is either a dedicated
					// FBO, or - in case its the final system backbuffer etc. - if preflip operations haven't been performed yet.
					// If non dedicated buffer (aka finalizedFBO) and preflip ops have already happened, then the backbuffer contains
					// final content for an upcoming Screen('Flip') and we can't use (and therefore taint) that buffer.
					if ((windowRecord->inputBufferFBO[viewid] == windowRecord->finalizedFBO[viewid]) && (windowRecord->backBufferBackupDone)) {
						// Target for resolve is finalized FBO (probably system backbuffer) and preflip ops have run already. We
						// can't do the resolve op, as this would screw up the backbuffer with the final stimulus:
						printf("PTB-ERROR: Tried to 'GetImage' from a multisampled 'drawBuffer', but can't perform anti-aliasing pass due to\n");
						printf("PTB-ERROR: lack of a dedicated resolve buffer.\n");
						printf("PTB-ERROR: You can get what you wanted by either one of two options:\n");
						printf("PTB-ERROR: Either enable a processing stage in the imaging pipeline, even if you don't need it, e.g., by setting\n");
						printf("PTB-ERROR: the imagingmode argument in the 'OpenWindow' call to kPsychNeedImageProcessing. This will create a\n");
						printf("PTB-ERROR: suitable resolve buffer. Or place the 'GetImage' call before any Screen('DrawingFinished') call, then\n");
						printf("PTB-ERROR: i can (ab-)use the system backbuffer as a temporary resolve buffer.\n\n");
						PsychErrorExitMsg(PsychError_user, "Tried to 'GetImage' from a multi-sampled 'drawBuffer'. Unsupported operation under given conditions.");						
					}
					else {
						// Ok, the inputBufferFBO is a suitable temporary resolve buffer. Perform a multisample resolve blit to it:
						// A simple glBlitFramebufferEXT() call will do the copy & downsample operation:
						glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->drawBufferFBO[viewid]]->fboid);
						glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->fboid);
						glBlitFramebufferEXT(0, 0, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->width, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->height,
											 0, 0, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->width, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->height,
											 GL_COLOR_BUFFER_BIT, GL_NEAREST);

						// Bind inputBuffer as framebuffer:
						glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, windowRecord->fboTable[windowRecord->inputBufferFBO[viewid]]->fboid);
						viewid = -1;
					}
				}
			}
			else {
				// No: Activate system framebuffer:
				PsychSetDrawingTarget(NULL);
			}
		}
		else {
			// Offscreen window or texture: Select drawing target as usual,
			// but set color attachment as read buffer:
			PsychSetDrawingTarget(windowRecord);
			whichBuffer = GL_COLOR_ATTACHMENT0_EXT;

			// We do not support multisampled readout:
			if (windowRecord->fboTable[windowRecord->drawBufferFBO[0]]->multisample > 0) {
				printf("PTB-ERROR: You tried to Screen('GetImage', ...); from an offscreen window or texture which has multisample anti-aliasing enabled.\n");
				printf("PTB-ERROR: This operation is not supported. You must first use Screen('CopyWindow') to create a non-multisampled copy of the\n");
				printf("PTB-ERROR: texture or offscreen window, then use 'GetImage' on that copy. The copy will be anti-aliased, so you'll get what you\n");
				printf("PTB-ERROR: wanted with a bit more effort. Sorry for the inconvenience, but this is mostly a hardware limitation.\n\n");
				
				PsychErrorExitMsg(PsychError_user, "Tried to 'GetImage' from a multi-sampled texture or offscreen window. Unsupported operation.");
			}
		}
	}
	else {
		// Normal case: No FBO based imaging - Select drawing target as usual:
		PsychSetDrawingTarget(windowRecord);
	}
	
    if (!isOES) {
        // Select requested read buffer, after some double-check:
        if (whichBuffer == 0) PsychErrorExitMsg(PsychError_user, "Invalid or unknown 'bufferName' argument provided.");
        glReadBuffer(whichBuffer);

        if (PsychPrefStateGet_Verbosity() > 5) printf("PTB-DEBUG: In Screen('GetImage'): GL-Readbuffer whichBuffer = %i\n", whichBuffer);
    }
    else {
        // OES: No way to select readbuffer, it is "hard-coded" by system spec, depending
        // on framebuffer. For bound FBO, always color attachment zero, for system framebuffer,
        // always front buffer on single-buffered setup, back buffer on double-buffered setup:
        if (buffername && PsychIsOnscreenWindow(windowRecord) && (whichBuffer != GL_COLOR_ATTACHMENT0_EXT)) {
            // Some part of the real system framebuffer of an onscreen window explicitely requested.
            if ((windowRecord->windowType == kPsychSingleBufferOnscreen) && (whichBuffer != GL_FRONT) && (PsychPrefStateGet_Verbosity() > 1)) {
                printf("PTB-WARNING: Tried to Screen('GetImage') single-buffered framebuffer '%s', but only 'frontBuffer' supported on OpenGL-ES. Returning that instead.\n", buffername);
            }
            
            if ((windowRecord->windowType == kPsychDoubleBufferOnscreen) && (whichBuffer != GL_BACK) && (PsychPrefStateGet_Verbosity() > 1)) {
                printf("PTB-WARNING: Tried to Screen('GetImage') double-buffered framebuffer '%s', but only 'backBuffer' supported on OpenGL-ES. Returning that instead.\n", buffername);
            }
        }
    }

    if (whichBuffer == GL_COLOR_ATTACHMENT0_EXT) {
        // FBO of texture / offscreen window / onscreen drawBuffer/inputBuffer
        // has size of clientrect -- potentially larger or smaller than backbuffer:
        PsychCopyRect(windowRect, windowRecord->clientrect);
    }
    else {
        // Non-FBO backed texture / offscreen window / onscreen window has size
        // of raw rect (==clientrect for non-onscreen, == backbuffer size for onscreen):
        PsychCopyRect(windowRect, windowRecord->rect);
    }

	// Retrieve optional read rectangle:    
	if(!PsychCopyInRectArg(2, FALSE, sampleRect)) PsychCopyRect(sampleRect, windowRect);
    
	if (IsPsychRectEmpty(sampleRect)) return(PsychError_none);

	// Compute sampling rectangle:
	if ((PsychGetWidthFromRect(sampleRect) >= INT_MAX) || (PsychGetHeightFromRect(sampleRect) >= INT_MAX)) {
		PsychErrorExitMsg(PsychError_user, "Too big 'rect' argument provided. Both width and height of the rect must not exceed 2^31 pixels!");
	}

	sampleRectWidth = (size_t) PsychGetWidthFromRect(sampleRect);
	sampleRectHeight= (size_t) PsychGetHeightFromRect(sampleRect);

	// Regular image fetch to runtime, or adding to a movie?
	if (!isAddMovieFrame) {
		// Regular fetch:

		// Get optional floatprecision flag: We return data with float-precision if
		// this flag is set. By default we return uint8 data:
		PsychCopyInFlagArg(4, FALSE, &floatprecision);
		
		// Get the optional number of channels flag: By default we return 3 channels,
		// the Red, Green, and blue color channel:
		nrchannels = 3;
		PsychCopyInIntegerArg(5, FALSE, &nrchannels);
		if (nrchannels < 1 || nrchannels > 4) PsychErrorExitMsg(PsychError_user, "Number of requested channels 'nrchannels' must be between 1 and 4!");
		
		if (!floatprecision) {
			// Readback of standard 8bpc uint8 pixels:  

            // No Luminance + Alpha on OES:
            if (isOES && (nrchannels == 2)) PsychErrorExitMsg(PsychError_user, "Number of requested channels 'nrchannels' == 2 not supported on OpenGL-ES!");

			PsychAllocOutUnsignedByteMatArg(1, TRUE, (int) sampleRectHeight, (int) sampleRectWidth, (int) nrchannels, &returnArrayBase);
            if (isOES) {
                // We only do RGBA reads on OES, then discard unwanted stuff ourselves:
                redPlane  = (psych_uint8*) PsychMallocTemp((size_t) 4 * sampleRectWidth * sampleRectHeight);
            }
            else {
                redPlane  = (psych_uint8*) PsychMallocTemp((size_t) nrchannels * sampleRectWidth * sampleRectHeight);
            }
			planeSize = sampleRectWidth * sampleRectHeight;

			glPixelStorei(GL_PACK_ALIGNMENT,1);
			invertedY = (int) (windowRect[kPsychBottom] - sampleRect[kPsychBottom]);

            if (isOES) {
                glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGBA, GL_UNSIGNED_BYTE, redPlane);
                stride = 4;
            }
            else {
                stride = nrchannels;
                if (nrchannels==1) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RED, GL_UNSIGNED_BYTE, redPlane); 
                if (nrchannels==2) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, redPlane);
                if (nrchannels==3) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGB, GL_UNSIGNED_BYTE, redPlane);
                if (nrchannels==4) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGBA, GL_UNSIGNED_BYTE, redPlane);
            }
			
			//in one pass transpose and flip what we read with glReadPixels before returning.  
			//-glReadPixels insists on filling up memory in sequence by reading the screen row-wise whearas Matlab reads up memory into columns.
			//-the Psychtoolbox screen as setup by gluOrtho puts 0,0 at the top left of the window but glReadPixels always believes that it's at the bottom left.     
			for(ix=0; ix < sampleRectWidth; ix++){
				for(iy=0; iy < sampleRectHeight; iy++){
					// Compute write-indices for returned data:
					redReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, nrchannels, iy, ix, 0);
					greenReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 1);
					blueReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 2);
					alphaReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 3);
					
					// Always return RED/LUMINANCE channel:
					returnArrayBase[redReturnIndex] = redPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 0];  
					// Other channels on demand:
					if (nrchannels>1) returnArrayBase[greenReturnIndex] = redPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 1];
					if (nrchannels>2) returnArrayBase[blueReturnIndex]  = redPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 2];
					if (nrchannels>3) returnArrayBase[alphaReturnIndex] = redPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 3];
				}
			}		
		}
		else {
			// Readback of standard 32bpc float pixels into a double matrix:  

            // No Luminance + Alpha on OES:
            if (isOES && (nrchannels == 2)) PsychErrorExitMsg(PsychError_user, "Number of requested channels 'nrchannels' == 2 not supported on OpenGL-ES!");

            // Only float readback on floating point FBO's with EXT_color_buffer_float support:
            if (isOES && ((whichBuffer != GL_COLOR_ATTACHMENT0_EXT) || (windowRecord->bpc < 16) || !glewIsSupported("GL_EXT_color_buffer_float"))) {
                printf("PTB-ERROR: Tried to 'GetImage' pixels in floating point format from a non-floating point surface, or not supported by your hardware.\n");
                PsychErrorExitMsg(PsychError_user, "'GetImage' of floating point values from given object not supported on OpenGL-ES!");
            }

			PsychAllocOutDoubleMatArg(1, TRUE, (int) sampleRectHeight, (int) sampleRectWidth, (int) nrchannels, &returnArrayBaseDouble);
            if (isOES) {
                dredPlane = (float*) PsychMallocTemp((size_t) 4 * sizeof(float) * sampleRectWidth * sampleRectHeight);
                stride = 4;
            }
            else {
                dredPlane = (float*) PsychMallocTemp((size_t) nrchannels * sizeof(float) * sampleRectWidth * sampleRectHeight);
                stride = nrchannels;
            }
			planeSize = sampleRectWidth * sampleRectHeight * sizeof(float);

			glPixelStorei(GL_PACK_ALIGNMENT, 1);
			invertedY = (int) (windowRect[kPsychBottom]-sampleRect[kPsychBottom]);

            if (!isOES) {
                if (nrchannels==1) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RED, GL_FLOAT, dredPlane); 
                if (nrchannels==2) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_LUMINANCE_ALPHA, GL_FLOAT, dredPlane);
                if (nrchannels==3) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGB, GL_FLOAT, dredPlane);
                if (nrchannels==4) glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGBA, GL_FLOAT, dredPlane);
            }
            else {
                glReadPixels((int) sampleRect[kPsychLeft], invertedY, (int) sampleRectWidth, (int) sampleRectHeight, GL_RGBA, GL_FLOAT, dredPlane);
            }

			//in one pass transpose and flip what we read with glReadPixels before returning.  
			//-glReadPixels insists on filling up memory in sequence by reading the screen row-wise whearas Matlab reads up memory into columns.
			//-the Psychtoolbox screen as setup by gluOrtho puts 0,0 at the top left of the window but glReadPixels always believes that it's at the bottom left.     
			for(ix=0; ix < sampleRectWidth; ix++){
				for(iy=0; iy < sampleRectHeight; iy++){
					// Compute write-indices for returned data:
					redReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth, nrchannels, iy, ix, 0);
					greenReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 1);
					blueReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 2);
					alphaReturnIndex=PsychIndexElementFrom3DArray(sampleRectHeight, sampleRectWidth,  nrchannels, iy, ix, 3);
					
					// Always return RED/LUMINANCE channel:
					returnArrayBaseDouble[redReturnIndex] = dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 0];  
					// Other channels on demand:
					if (nrchannels>1) returnArrayBaseDouble[greenReturnIndex] = dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 1];
					if (nrchannels>2) returnArrayBaseDouble[blueReturnIndex]  = dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 2];
					if (nrchannels>3) returnArrayBaseDouble[alphaReturnIndex] = dredPlane[(ix + ((sampleRectHeight-1) - iy ) * sampleRectWidth) * (size_t) stride + 3];
				}
			}		
		}
	}
	
	if (isAddMovieFrame) {
		// Adding of image to a movie requested:
		
		// Get optional moviehandle:
		moviehandle = 0;
		PsychCopyInIntegerArg(4, FALSE, &moviehandle);
		if (moviehandle < 0) PsychErrorExitMsg(PsychError_user, "Provided 'moviehandle' is negative. Must be greater or equal to zero!");
		
		// Get optional frameduration:
		frameduration = 1;
		PsychCopyInIntegerArg(5, FALSE, &frameduration);
		if (frameduration < 1) PsychErrorExitMsg(PsychError_user, "Number of requested framedurations 'frameduration' is negative. Must be greater than zero!");
		
        framepixels = PsychGetVideoFrameForMoviePtr(moviehandle, &twidth, &theight, &numChannels, &bitdepth);
		if (framepixels) {
			glPixelStorei(GL_PACK_ALIGNMENT,1);
			invertedY = (int) (windowRect[kPsychBottom] - sampleRect[kPsychBottom]);
			
            if (isOES) {
                if (bitdepth != 8) PsychErrorExitMsg(PsychError_user, "AddFrameToMovie failed due to wrong bpc value. Only 8 bpc supported on OpenGL-ES.");

                if (numChannels == 4) {
                    // OES: BGRA supported?
                    if (glewIsSupported("GL_EXT_read_format_bgra")) {
                        // Yep: Readback in a compatible and acceptably fast format:
                        glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_BGRA, GL_UNSIGNED_BYTE, framepixels);
                    }
                    else {
                        // Suboptimal readback path. will also cause swapped colors in movie writing:
                        glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_RGBA, GL_UNSIGNED_BYTE, framepixels);
                    }
                }
                else if (numChannels == 3) {
                    glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_RGB, GL_UNSIGNED_BYTE, framepixels);
                }
                else PsychErrorExitMsg(PsychError_user, "AddFrameToMovie failed due to wrong number of channels. Only 3 or 4 channels are supported on OpenGL-ES.");
            }
            else {
                // Desktop-GL: Use optimal format and support 16 bpc bitdepth as well.
                switch (numChannels) {
                    case 4:
                        glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_BGRA, (bitdepth <= 8) ? GL_UNSIGNED_INT_8_8_8_8 : GL_UNSIGNED_SHORT, framepixels);
                        break;
                        
                    case 3:
                        glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_RGB, (bitdepth <= 8) ? GL_UNSIGNED_BYTE : GL_UNSIGNED_SHORT, framepixels);
                        break;
                        
                    case 1:
                        glReadPixels((int) sampleRect[kPsychLeft], invertedY, twidth, theight, GL_RED, (bitdepth <= 8) ? GL_UNSIGNED_BYTE : GL_UNSIGNED_SHORT, framepixels);
                        break;
                        
                    default:
                        PsychErrorExitMsg(PsychError_user, "AddFrameToMovie failed due to wrong number of channels. Only 1, 3 or 4 channels are supported on OpenGL.");
                        break;
                }
            }

            // Add frame to movie, mark it as "upside down", with invalid -1 timestamp and a duration of frameduration ticks:
			if (PsychAddVideoFrameToMovie(moviehandle, frameduration, TRUE, -1) != 0) {
				PsychErrorExitMsg(PsychError_user, "AddFrameToMovie failed with error above!");
			}
		}
		else {
			PsychErrorExitMsg(PsychError_user, "Invalid 'moviePtr' provided. Doesn't correspond to a movie open for recording!");
		}
	}
	
	if (viewid == -1) {
		// Need to reset framebuffer binding to get rid of the inputBufferFBO which is bound due to
		// multisample resolve ops, or of other special FBO bindings --> Activate system framebuffer:
		PsychSetDrawingTarget(NULL);		
	}

	return(PsychError_none);
}
PsychError SCREENLoadNormalizedGammaTable(void) 
{
    int i, screenNumber, numEntries, inM, inN, inP, loadOnNextFlip, physicalDisplay, outputId;
    float *outRedTable, *outGreenTable, *outBlueTable, *inRedTable, *inGreenTable, *inBlueTable;
    double *inTable, *outTable;	
    PsychWindowRecordType *windowRecord;

    //all subfunctions should have these two lines
    PsychPushHelp(useString, synopsisString, seeAlsoString);
    if(PsychIsGiveHelp()){PsychGiveHelp();return(PsychError_none);};

    PsychErrorExit(PsychCapNumOutputArgs(1));
    PsychErrorExit(PsychCapNumInputArgs(4));

    // Get optional physicalDisplay argument - It defaults to zero on OS/X, -1 on Linux:
    physicalDisplay = -1;
    PsychCopyInIntegerArg(4, FALSE, &physicalDisplay);

    // Read in the screen number:
    // On OS/X we also accept screen indices for physical displays (as opposed to active dispays).
    // This only makes a difference in mirror-mode, where there is only 1 active display, but that
    // corresponds to two physical displays which can have different gamma setting requirements:
    if ((PSYCH_SYSTEM == PSYCH_OSX) && (physicalDisplay > 0)) {
        PsychCopyInIntegerArg(1, TRUE, &screenNumber);
        if (screenNumber < 1) PsychErrorExitMsg(PsychError_user, "A 'screenNumber' that is smaller than one provided, although 'physicalDisplay' flag set. This is not allowed!");

	// Invert screenNumber as a sign its a physical display, not an active display:
	screenNumber = -1 * screenNumber;
    }
    else {
        PsychCopyInScreenNumberArg(1, TRUE, &screenNumber);
    }

    if ((PSYCH_SYSTEM == PSYCH_LINUX) && (physicalDisplay > -1)) {
	// Affect one specific display output for given screen:
	outputId = physicalDisplay;
    }
    else {
	// Other OS'es, and Linux with default setting: Affect all outputs
	// for a screen.
	outputId = -1;
    }

    // Load and sanity check the input matrix:
    inM = -1; inN = -1; inP = -1;
    if (!PsychAllocInDoubleMatArg(2, FALSE, &inM,  &inN, &inP, &inTable)) {
        // Special case: Allow passing in an empty gamma table argument. This
        // triggers auto-load of identity LUT and setup of GPU for identity passthrough:
        inM = 0; inN = 3; inP = 1;
    }

    // Sanity check dimensions:
    if((inN != 3) || (inP != 1)) PsychErrorExitMsg(PsychError_user, "The gamma table must have 3 columns (Red, Green, Blue).");
	
    // Identity passthrouh setup requested?
    if (inM == 0) {
        // Yes. Try to enable it, return its status code:
        PsychAllocInWindowRecordArg(1, TRUE, &windowRecord);
        i = PsychSetGPUIdentityPassthrough(windowRecord, screenNumber, TRUE);
        PsychCopyOutDoubleArg(1, FALSE, (double) i);
        
        // Done.
        return(PsychError_none);
    }

	#if PSYCH_SYSTEM != PSYCH_WINDOWS
		// OS-X and Linux allow tables with other than 256 slots:
		// OS/X either passes them to hw if in native size, or performs
		// software interpolation to convert it into native size. We allow any table size with 1 - x slots.
		// A table size of 1 row will have a special meaning. It interprets the 1 row of the table as gamma formula
		// min, max, gamma and lets the OS compute a corresponding gamma correction table.
		// A table size of zero rows will trigger an internal upload of an identity table via byte transfer.
		// On Linux we need to interpolate ourselves on non-matching table sizes.
	#else
		// Windows requires 256 slots:
		if((inM != 256) && (inM != 0)) {
			PsychErrorExitMsg(PsychError_user, "The gamma table must have 256 rows.");
		}
	#endif
	
	 // Copy in optional loadOnNextFlip - flag. It defaults to zero. If provided
	 // with a non-zero value, we will defer actual update of the gamma table to
	 // the next bufferswap as initiated via Screen('Flip').
	 loadOnNextFlip = 0;
	 PsychCopyInIntegerArg(3, FALSE, &loadOnNextFlip);

	 if (loadOnNextFlip>0) {
		 if ((PSYCH_SYSTEM == PSYCH_OSX) && (physicalDisplay > 0)) PsychErrorExitMsg(PsychError_user, "Non-zero 'loadOnNextFlip' flag not allowed if 'physicalDisplays' flag is non-zero!");
		 if ((PSYCH_SYSTEM == PSYCH_LINUX) && (physicalDisplay > -1)) PsychErrorExitMsg(PsychError_user, "Non-zero 'loadOnNextFlip' flag not allowed if 'physicalDisplays' setting is positive!");

		 // Allocate tables in associated windowRecord: We will update during next
		 // Flip operation for specified windowRecord.
		 PsychAllocInWindowRecordArg(1, TRUE, &windowRecord);
		 
		 // Sanity checks:
		 if (!PsychIsOnscreenWindow(windowRecord)) PsychErrorExitMsg(PsychError_user, "Target window for gamma table upload is not an onscreen window!");
		 if (windowRecord->inRedTable && loadOnNextFlip!=2) PsychErrorExitMsg(PsychError_user, "This window has already a new gamma table assigned for upload on next Flip!");
		 
		 if (windowRecord->inRedTable && windowRecord->inTableSize != inM) {
			free(windowRecord->inRedTable); windowRecord->inRedTable = NULL;
			free(windowRecord->inGreenTable); windowRecord->inGreenTable = NULL;
			free(windowRecord->inBlueTable); windowRecord->inBlueTable = NULL;
		 }
		 
		 if (windowRecord->inRedTable == NULL) {
			 // Allocate persistent memory:
			 inRedTable=malloc(sizeof(float) * inM);
			 inGreenTable=malloc(sizeof(float) * inM);
			 inBlueTable=malloc(sizeof(float) * inM);
			 
			 // Assign the pointers to the windowRecord:
			 windowRecord->inRedTable = inRedTable;
			 windowRecord->inGreenTable = inGreenTable;
			 windowRecord->inBlueTable = inBlueTable;
			 windowRecord->inTableSize = inM;
		 }
		 else {
			inRedTable = windowRecord->inRedTable;
			inGreenTable = windowRecord->inGreenTable;
			inBlueTable = windowRecord->inBlueTable;
		 }
		
		 windowRecord->loadGammaTableOnNextFlip = (loadOnNextFlip == 1) ? 1 : 0;
	 }
	 else {
		 // Allocate temporary tables: We will update immediately.
		 inRedTable=PsychMallocTemp(sizeof(float) * inM);
		 inGreenTable=PsychMallocTemp(sizeof(float) * inM);
		 inBlueTable=PsychMallocTemp(sizeof(float) * inM);
	 }
	 
    for(i=0;i<inM;i++){
        inRedTable[i]=(float)inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i, 0, 0)];
        inGreenTable[i]=(float)inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i, 1, 0)];
        inBlueTable[i]=(float)inTable[PsychIndexElementFrom3DArray(inM, 3, 0, i, 2, 0)];

        if(inRedTable[i]>1 || inRedTable[i]< 0 || inGreenTable[i] > 1 || inGreenTable[i] < 0 || inBlueTable[i] >1 || inBlueTable[i] < 0)
            PsychErrorExitMsg(PsychError_user, "Gamma Table Values must be in interval 0 =< x =< 1");
    }

    if (loadOnNextFlip < 2) {
        //first read the existing gamma table so we can return it.  
        PsychReadNormalizedGammaTable(screenNumber, outputId, &numEntries, &outRedTable, &outGreenTable, &outBlueTable);
        PsychAllocOutDoubleMatArg(1, FALSE, numEntries, 3, 0, &outTable);
        
        for(i=0;i<numEntries;i++){
            outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 0, 0)]=(double)outRedTable[i];
            outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 1, 0)]=(double)outGreenTable[i];
            outTable[PsychIndexElementFrom3DArray(numEntries, 3, 0, i, 2, 0)]=(double)outBlueTable[i];
        }
    }
     
    //Now set the new gamma table
    if (loadOnNextFlip == 0) PsychLoadNormalizedGammaTable(screenNumber, outputId, inM, inRedTable, inGreenTable, inBlueTable);

    return(PsychError_none);
}