Exemple #1
0
// add the entire signal b to this signal, at the subpixel destination offset. 
// 
void MLSignal::add2D(const MLSignal& b, const Vec2& destOffset)
{
	MLSignal& a = *this;
		
	Vec2 iDestOffset, fDestOffset;
	destOffset.getIntAndFracParts(iDestOffset, fDestOffset);
	
	int destX = iDestOffset[0];
	int destY = iDestOffset[1];	
	float srcPosFX = fDestOffset[0];
	float srcPosFY = fDestOffset[1];
	
	MLRect srcRect(0, 0, b.getWidth() + 1, b.getHeight() + 1); // add (1, 1) for interpolation
	MLRect destRect = srcRect.translated(iDestOffset).intersect(getBoundsRect());
	
	for(int j=destRect.top(); j<destRect.bottom(); ++j)
	{
		for(int i=destRect.left(); i<destRect.right(); ++i)
		{
			a(i, j) += b.getInterpolatedLinear(i - destX - srcPosFX, j - destY - srcPosFY);
		}
	}

	setConstant(false);
}
Exemple #2
0
// TODO SSE
void MLSignal::sigLerp(const MLSignal& b, const MLSignal& mix)
{
	int n = min(mSize, b.getSize());
	n = min(n, mix.getSize());
	for(int i = 0; i < n; ++i)
	{
		mDataAligned[i] = lerp(mDataAligned[i], b.mDataAligned[i], mix.mDataAligned[i]);
	}
	setConstant(false);
}
Exemple #3
0
// note: order of properties is important! delays property will set
// the number of delays and clear other peoperties.
void FDN::setProperty(Symbol name, MLProperty value)
{
	MLSignal sigVal = value.getSignalValue();
	int currentSize = mDelays.size();
	int newSize = sigVal.getWidth();
	
	if(name == "delays")
	{
		// setting number of delays outside of bounds will turn object into a passthru
		if(!within(newSize, 3, 17))
		{
			// TODO report error
			newSize = 0;
		}
		
		// resize if needed.
		if(newSize != currentSize)
		{
			mDelays.resize(newSize);
			mFilters.resize(newSize);
			mDelayInputVectors.resize(newSize);
			mFeedbackGains.setDims(newSize);
		}
		
		// set default feedbacks.
		for(int n=0; n<newSize; ++n)
		{
			mFeedbackGains[n] = 1.f;
		}
		
		// set delay times.
		for(int n=0; n<newSize; ++n)
		{
			// we have one DSPVector feedback latency, so delay times can't be smaller than that
			int len = sigVal[n] - kFloatsPerDSPVector;
			len = max(1, len);
			mDelays[n].setDelayInSamples(len);
		}
		clear();
	}
	else if(name == "cutoffs")
	{
		// compute coefficients from cutoffs
		int newValues = min(currentSize, newSize);
		for(int n=0; n<newValues; ++n)
		{
			mFilters[n].setCoeffs(biquadCoeffs::onePole(sigVal[n]));
		}
	}
	else if(name == "gains")
	{
		mFeedbackGains.copy(sigVal);
	}
}
Exemple #4
0
// TODO SSE
void MLSignal::sigClamp(const MLSignal& a, const MLSignal& b)
{
	int n = min(mSize, a.getSize());
	n = min(n, b.getSize());
	for(int i = 0; i < n; ++i)
	{
		MLSample f = mDataAligned[i];
		mDataAligned[i] = clamp(f, a.mDataAligned[i], b.mDataAligned[i]);
	}
	setConstant(false);
}
// set up coefficient signals
MLProc::err MLProcBiquad::resize() 
{	
	MLProc::err e = OK;
	int b = getContextVectorSize();
	mA0.setDims(b);
	mA1.setDims(b);
	mA2.setDims(b);
	mB1.setDims(b);
	mB2.setDims(b);
	
	// TODO check
	return e;
}
void TouchTracker::Calibrator::setCalibration(const MLSignal& v)
{
	if((v.getHeight() == kTemplateSize) && (v.getWidth() == kTemplateSize))
	{
        mCalibrateSignal = v;
        mHasCalibration = true;
    }
    else
    {
		MLConsole() << "TouchTracker::Calibrator::setCalibration: bad size, restoring default.\n";
        mHasCalibration = false;
    }
}
void TouchTracker::Calibrator::setNormalizeMap(const MLSignal& v)
{
	if((v.getHeight() == mSrcHeight) && (v.getWidth() == mSrcWidth))
	{
		mNormalizeMap = v;
		mHasNormalizeMap = true;
	}
	else
	{
		MLConsole() << "TouchTracker::Calibrator::setNormalizeMap: restoring default.\n";
		mNormalizeMap.fill(1.f);
		mHasNormalizeMap = false;
	}
}
Exemple #8
0
void MLSignal::copy(const MLSignal& b)
{
	const bool kb = b.isConstant();
	if (kb)
	{
		setToConstant(b.mDataAligned[0]);
	}
	else 
	{
		const int n = min(mSize, b.getSize());
		std::copy(b.mDataAligned, b.mDataAligned + n, mDataAligned);
		setConstant(false);
	}
}
Exemple #9
0
// add the entire signal b to this signal, at the integer destination offset. 
// 
void MLSignal::add2D(const MLSignal& b, int destX, int destY)
{
	MLSignal& a = *this;
	MLRect srcRect(0, 0, b.getWidth(), b.getHeight());
	MLRect destRect = srcRect.translated(Vec2(destX, destY)).intersect(getBoundsRect());
	
	for(int j=destRect.top(); j<destRect.bottom(); ++j)
	{
		for(int i=destRect.left(); i<destRect.right(); ++i)
		{
			a(i, j) += b(i - destX, j - destY);
		}
	}

	setConstant(false);
}
void TouchTracker::Calibrator::normalizeInput(MLSignal& in)
{
	if(mHasNormalizeMap)
	{
		in.multiply(mNormalizeMap);
	}
}
Exemple #11
0
// setFrame() - set the 2D frame i to the incoming signal.
void MLSignal::setFrame(int i, const MLSignal& src)
{
	// only valid for 3D signals
	assert(is3D());
	
	// source must be 2D
	assert(src.is2D());
	
	// src signal should match our dimensions
	if((src.getWidth() != mWidth) || (src.getHeight() != mHeight))
	{
		return;
	}
	
	MLSample* pDestFrame = mDataAligned + plane(i);
	const MLSample* pSrc = src.getConstBuffer();
	std::copy(pSrc, pSrc + src.getSize(), pDestFrame);
}
Exemple #12
0
// a simple pixel-by-pixel measure of the distance between two signals.
//
float rmsDifference2D(const MLSignal& a, const MLSignal& b)
{
	int w = min(a.getWidth(), b.getWidth());
	int h = min(a.getHeight(), b.getHeight());
	float sum = 0.;
	float d;
	for(int j=0; j<h; ++j)
	{
		for(int i=0; i<w; ++i)
		{
			d = a(i, j) - b(i, j);
			sum += d*d;
		}
	}
	sum /= w*h;
	sum = sqrtf(sum);
	return sum;
}
Exemple #13
0
void MLSignal::sigMax(const MLSignal& b)
{
	int n = min(mSize, b.getSize());
	for(int i = 0; i < n; ++i)
	{
		MLSample f = mDataAligned[i];
		mDataAligned[i] = max(f, b.mDataAligned[i]);
	}
	setConstant(false);
}
Exemple #14
0
// TODO SSE
void MLSignal::divide(const MLSignal& b)
{
	const bool ka = isConstant();
	const bool kb = b.isConstant();
	if (ka && kb)
	{
		setToConstant(mDataAligned[0] + b.mDataAligned[0]);
	}
	else 
	{
		const int n = min(mSize, b.getSize());
		if (ka && !kb)
		{
			MLSample fa = mDataAligned[0];
			for(int i = 0; i < n; ++i)
			{
				mDataAligned[i] = fa / b[i];
			}
		}
		else if (!ka && kb)
		{
			MLSample fb = b[0];
			for(int i = 0; i < n; ++i)
			{
				mDataAligned[i] /= fb;
			}
		}
		else
		{
			for(int i = 0; i < n; ++i)
			{
				mDataAligned[i] /= b.mDataAligned[i];
			}
		}
		setConstant(false);
	}
}
void TouchTracker::addPeakToKeyState(const MLSignal& in)
{
	mTemp.copy(in);
	for(int i=0; i<kMaxPeaksPerFrame; ++i)
	{
		// get highest peak from temp.  
		Vec3 peak = mTemp.findPeak();	
		float z = peak.z();
		
		// add peak to key state, or bail
		if (z > mOnThreshold)
		{			
			Vec2 pos = in.correctPeak(peak.x(), peak.y());	
			int key = getKeyIndexAtPoint(pos);
			if(within(key, 0, mNumKeys))
			{
				// send peak energy to key under peak.
				KeyState& keyState = mKeyStates[key];
				MLRange kdzRange(mOnThreshold, mMaxForce*0.5, 0.001f, 1.f);
				float iirCoeff = kdzRange.convertAndClip(z);	
				float dt = mCalibrator.differenceFromTemplateTouch(in, pos);
                
                //debug() << "new PEAK dt: " << dt << "\n";
                
				keyState.mK = iirCoeff;
				keyState.zIn = z;
				keyState.dtIn = dt;
				if(mQuantizeToKey)
				{
					keyState.posIn = keyState.mKeyCenter;
				}
				else
				{
					keyState.posIn = pos;
				}
			}
		}
		else
		{
			break;
		}
	}
}							
Exemple #16
0
// constructor for making loops. only one type for now. we could loop in different directions and dimensions.
MLSignal::MLSignal(MLSignal other, eLoopType loopType, int loopSize) :
mData(0),
mDataAligned(0),
mCopy(0),
mCopyAligned(0)
{
	switch(loopType)
	{
		case kLoopType1DEnd:
		default:
		{
			int w = other.getWidth();
			int loopWidth = clamp(loopSize, 0, w);
			setDims(w + loopWidth, 1, 1);
			mRate = other.mRate;
			std::copy(other.mDataAligned, other.mDataAligned + w, mDataAligned);
			std::copy(other.mDataAligned, other.mDataAligned + loopWidth, mDataAligned + w);
		}
		break;
	}
}
void MLProcBiquad::calcCoeffs(const int frames) 
{
	static MLSymbol modeSym("mode");
	int mode = (int)getParam(modeSym);
	const MLSignal& frequency = getInput(2);
	const MLSignal& q = getInput(3);
	int coeffFrames;
	
	float twoPiOverSr = kMLTwoPi*getContextInvSampleRate();		

	bool paramSignalsAreConstant = frequency.isConstant() && q.isConstant();
	
	if (paramSignalsAreConstant)
	{
		coeffFrames = 1;
	}
	else
	{
		coeffFrames = frames;
	}
	
	// set proper constant state for coefficient signals
	mA0.setConstant(paramSignalsAreConstant);
	mA1.setConstant(paramSignalsAreConstant);
	mA2.setConstant(paramSignalsAreConstant);
	mB1.setConstant(paramSignalsAreConstant);
	mB2.setConstant(paramSignalsAreConstant);
	
	float a0, a1, a2, b0, b1, b2;
	float qm1, omega, alpha, sinOmega, cosOmega;
	float highLimit = getContextSampleRate() * 0.33f;
				
	// generate coefficient signals
	// TODO SSE
	for(int n=0; n<coeffFrames; ++n)
	{
		qm1 = 1.f/(q[n] + 0.05f);
		omega = clamp(frequency[n], kLowFrequencyLimit, highLimit) * twoPiOverSr;
		sinOmega = fsin1(omega);
		cosOmega = fcos1(omega);
		alpha = sinOmega * 0.5f * qm1;
		b0 = 1.f/(1.f + alpha);
				
		switch (mode) 
		{
		default:
		case kLowpass:
			a0 = ((1.f - cosOmega) * 0.5f) * b0;
			a1 = (1.f - cosOmega);
			a2 = a0;
			b1 = (-2.f * cosOmega);
			b2 = (1.f - alpha);		
			break;
				
		case kHighpass:		
			a0 = ((1.f + cosOmega) * 0.5f);
			a1 = -(1.f + cosOmega);
			a2 = a0;
			b1 = (-2.f * cosOmega);
			b2 = (1.f - alpha);
			break;
				
		case kBandpass:
			a0 = alpha;
			a1 = 0.f;
			a2 = -alpha;
			b1 = -2.f * cosOmega;
			b2 = (1.f - alpha);
			break;
			
		case kNotch:
			a0 = 1;
			a1 = -2.f * cosOmega;
			a2 = 1;
			b1 = -2.f * cosOmega;
			b2 = (1.f - alpha);
			break;
		}
						
		mA0[n] = a0*b0;
		mA1[n] = a1*b0;
		mA2[n] = a2*b0;
		mB1[n] = b1*b0;
		mB2[n] = b2*b0;
	}
}
Exemple #18
0
// read a ring buffer into the given row of the destination signal.
//
int MLProcRingBuffer::readToSignal(MLSignal& outSig, int samples, int row)
{
	int lastRead = 0;
	int skipped = 0;
	int available = 0;
	MLSample * outBuffer = outSig.getBuffer() + outSig.row(row);
	void * trashBuffer = (void *)mTrashSignal.getBuffer();
	MLSample * trashbufferAsSamples = reinterpret_cast<MLSample*>(trashBuffer);
	static MLSymbol modeSym("mode");
	int mode = (int)getParam(modeSym);
	bool underTrigger = false;
	MLSample triggerVal = 0.f;
		
	samples = min(samples, (int)outSig.getWidth());
	available = (int)PaUtil_GetRingBufferReadAvailable( &mBuf );
    
    // return if we have not accumulated enough signal.
	if (available < samples) return 0;
	
	// depending on trigger mode, trash samples up to the ones we will return.
	switch(mode)
	{
		default:
		case eMLRingBufferNoTrash:
		break;
		
		case eMLRingBufferUpTrig:		
			while (available >= samples+1)	
			{
				// read buffer
				lastRead = (int)PaUtil_ReadRingBuffer( &mBuf, trashBuffer, 1 );
				skipped += lastRead;
				available = (int)PaUtil_GetRingBufferReadAvailable( &mBuf );
				if(trashbufferAsSamples[0] < triggerVal)
				{
					underTrigger = true;
				}
				else
				{
					if (underTrigger == true) break;
					underTrigger = false;
				}
			}
		break;		

		case eMLRingBufferMostRecent:			
			if (available > samples)
			{
				// TODO modify pa ringbuffer instead of reading to trash buffer. 
				lastRead = (int)PaUtil_ReadRingBuffer( &mBuf, trashBuffer, available - samples );  
				// skipped += lastRead;
			}			
		break;
	}
	
    lastRead = (int)PaUtil_ReadRingBuffer( &mBuf, outBuffer, samples );

	// DEBUG
	/*
	const MLSymbol& myName = getName();
	if (!myName.compare("body_position_x_out"))
	{
		available = PaUtil_GetRingBufferReadAvailable( &mBuf );
		if ((skipped == 0) && (lastRead == 0))
		{
			debug() << "-";
		}
		else
		{
	debug() << getName() << " requested " << samples << " read " << lastRead << ", skipped " << skipped << ", avail. " << available << "\n";
		}
	}
	*/

	return lastRead;
}
// expire or move existing touches based on new signal input. 
// 
void TouchTracker::updateTouches(const MLSignal& in)
{
	// copy input signal to border land
	int width = in.getWidth();
	int height = in.getHeight();
	
	mTemp.copy(in);
	mTemplateMask.clear();
	
	// sort active touches by Z
	// copy into sorting container, referring back to unsorted touches
	int activeTouches = 0;
	for(int i = 0; i < mMaxTouchesPerFrame; ++i)
	{
		Touch& t = mTouches[i];
		if (t.isActive())
		{
			t.unsortedIdx = i;
			mTouchesToSort[activeTouches++] = t;
		}
	}

	std::sort(mTouchesToSort.begin(), mTouchesToSort.begin() + activeTouches, compareTouchZ());

	// update active touches in sorted order, referring to existing touches in place
	for(int i = 0; i < activeTouches; ++i)
	{
		int refIdx = mTouchesToSort[i].unsortedIdx;
		Touch& t = mTouches[refIdx];
		Vec2 pos(t.x, t.y); 
		Vec2 newPos = pos;
		float newX = t.x;
		float newY = t.y;
		float newZ = in.getInterpolatedLinear(pos);
		
		// if not preparing to remove, update position.
		if (t.releaseCtr == 0)
		{
			Vec2 minPos(0, 0);
			Vec2 maxPos(width, height);
			int ix = floor(pos.x() + 0.5f);
			int iy = floor(pos.y() + 0.5f);		
			
			// move to any higher neighboring integer value
			Vec2 newPeak;
			newPeak = adjustPeak(mTemp, ix, iy);			
			Vec2 newPeakI, newPeakF;
			newPeak.getIntAndFracParts(newPeakI, newPeakF);
			int newPx = newPeakI.x();
			int newPy = newPeakI.y();
			
			// get exact location and new key
			Vec2 correctPos = mTemp.correctPeak(newPx, newPy);
			newPos = correctPos;	
			int newKey = getKeyIndexAtPoint(newPos);												
			
			// move the touch.  
			if((newKey == t.key) || !keyIsOccupied(newKey))
			{			
				// This must be the only place a touch can move from key to key.
				pos = newPos;
				newX = pos.x();
				newY = pos.y();					
				t.key = newKey;
			}							
		}
		
		// look for reasons to release
		newZ = in.getInterpolatedLinear(newPos);
		bool thresholdTest = (newZ > mOffThreshold);			
		float inhibit = getInhibitThreshold(pos);
		bool inhibitTest = (newZ > inhibit);
		t.tDist = mCalibrator.differenceFromTemplateTouchWithMask(mTemp, pos, mTemplateMask);
		bool templateTest = (t.tDist < mTemplateThresh);
		bool overrideTest = (newZ > mOverrideThresh);
						
		t.age++;

		// handle release		
		// TODO get releaseDetect: evidence that touch has been released.
		// from matching release curve over ~ 50 samples. 
		if (!thresholdTest || (!templateTest && !overrideTest) || (!inhibitTest))
		{			
			/* debug
			if(!thresholdTest && (t.releaseCtr == 0))
			{
				debug() << refIdx << " REL thresholdFail: " << newZ << " at " << pos << "\n";	
			}
			if(!inhibitTest && (t.releaseCtr == 0))
			{
				debug() << refIdx << " REL inhibitFail: " << newZ << " < " << inhibit << "\n";	
			}
			if(!templateTest && (t.releaseCtr == 0))
			{
				debug() << refIdx << " REL templateFail: " << t.tDist << " at " << pos << "\n";	
			}			
			*/
			if(t.releaseCtr == 0)
			{
				t.releaseSlope = t.z / (float)kTouchReleaseFrames;
			}
			t.releaseCtr++;
			newZ = t.z - t.releaseSlope;
		}
		else
		{	
			// reset off counter 
			t.releaseCtr = 0;	
		}

		// filter position and assign new touch values
		const float e = 2.718281828;
		float xyCutoff = (newZ - mOnThreshold) / (mMaxForce*0.25);
		xyCutoff = clamp(xyCutoff, 0.f, 1.f);
		xyCutoff *= xyCutoff;
		xyCutoff *= xyCutoff;
		xyCutoff = xyCutoff*100.;
		xyCutoff = clamp(xyCutoff, 1.f, 100.f);
		float x = powf(e, -kMLTwoPi * xyCutoff / (float)mSampleRate);
		float a0 = 1.f - x;
		float b1 = -x;
		t.dz = newZ - t.z;	
		
		// these can't be filtered too much or updateTouches will not work
		// for fast movements.  Revisit when we rewrite the touch tracker.		
		t.x = a0*newX - b1*t.x;
		t.y = a0*newY - b1*t.y;
		t.z = newZ;
		
		// filter z based on user lowpass setting and touch age
		float lp = mLopass;
		lp -= t.age*(mLopass*0.75f/kAttackFrames);
		lp = clamp(lp, mLopass, mLopass*0.25f);	// WTF???		
				
		float xz = powf(e, -kMLTwoPi * lp / (float)mSampleRate);
		float a0z = 1.f - xz;
		float b1z = -xz;
		t.zf = a0z*(newZ - mOnThreshold) - b1z*t.zf;	
				
		
		// remove touch if filtered z is below threshold
		if(t.zf < 0.)
		{
			// debug() << refIdx << " OFF with z:" << t.z << " td:" << t.tDist <<  "\n";	
			removeTouchAtIndex(refIdx);
		}
		
		// subtract updated touch from the input sum.
		// mTemplateScaled is scratch space. 
		mTemplateScaled.clear();
		mTemplateScaled.add2D(mCalibrator.getTemplate(pos), 0, 0);
		mTemplateScaled.scale(-t.z*mCalibrator.getZAdjust(pos)); 
														
		mTemp.add2D(mTemplateScaled, Vec2(pos - Vec2(kTemplateRadius, kTemplateRadius)));
		mTemp.sigMax(0.0);

		// add touch neighborhood to template mask. This allows crowded touches
		// to pass the template test by ignoring areas shared with other touches.
		Vec2 maskPos(t.x, t.y);
		const MLSignal& tmplate = mCalibrator.getTemplate(maskPos);
		mTemplateMask.add2D(tmplate, maskPos - Vec2(kTemplateRadius, kTemplateRadius));
	}
}
// if any neighbors of the input coordinates are higher, move the coordinates there.
//
Vec2 TouchTracker::adjustPeak(const MLSignal& in, int xp, int yp)
{
	int width = in.getWidth();
	int height = in.getHeight();
	
	int x = clamp(xp, 1, width - 2);
	int y = clamp(yp, 1, height - 2);
										
	float t = 0.0;
	int rx = x;
	int ry = y;
	float a = in(x - 1, y - 1);
	float b = in(x, y - 1);
	float c = in(x + 1, y - 1);
	float d = in(x - 1, y);
	float e = in(x, y);
	float f = in(x + 1, y);
	float g = in(x - 1, y + 1);
	float h = in(x, y + 1);
	float i = in(x + 1, y + 1);
	float fmax = e;
	
	if (y > 0)
	{
		if (a > fmax + t)
		{
//			debug() << "<^ ";
			fmax = a; rx = x - 1; ry = y - 1;		
		}
		if (b > fmax + t)
		{
//			debug() << "^ ";
			fmax = b; rx = x; ry = y - 1;		
		}
		if (c > fmax + t)
		{
//			debug() << ">^ ";
			fmax = c; rx = x + 1; ry = y - 1;		
		}
	}
	if (d > fmax + t)
	{
//		debug() << "<- ";
		fmax = d; rx = x - 1; ry = y;		
	}
	if (f > fmax + t)
	{
//		debug() << "-> ";
		fmax = f; rx = x + 1; ry = y;		
	}
	if (y < in.getHeight() - 1)
	{
		if (g > fmax + t)
		{
//			debug() << "<_ ";
			fmax = g; rx = x - 1; ry = y + 1;		
		}
		if (h > fmax + t)
		{
//			debug() << "_ ";
			fmax = h; rx = x; ry = y + 1;		
		}
		if (i > fmax + t)
		{
//			debug() << ">_ ";
			fmax = i; rx = x + 1; ry = y + 1;		
		}
	}
	return Vec2(rx, ry);
}
float TouchTracker::Calibrator::differenceFromTemplateTouchWithMask(const MLSignal& in, Vec2 pos, const MLSignal& mask)
{
	static float maskThresh = 0.001f;
	static MLSignal a2(kTemplateSize, kTemplateSize);
	static MLSignal b(kTemplateSize, kTemplateSize);
	static MLSignal b2(kTemplateSize, kTemplateSize);

	float r = 0.f;
	int height = in.getHeight();
	int width = in.getWidth();
	MLRect boundsRect(0, 0, width, height);
	
	// use linear interpolated z value from input
	float linearZ = in.getInterpolatedLinear(pos)*getZAdjust(pos);
	linearZ = clamp(linearZ, 0.00001f, 1.f);
	float z1 = 1./linearZ;	
	const MLSignal& a = getTemplate(pos);
	
	// get normalized input values surrounding touch
	int tr = kTemplateRadius;
	b.clear();
	for(int j=0; j < kTemplateSize; ++j)
	{
		for(int i=0; i < kTemplateSize; ++i)
		{
			Vec2 vInPos = pos + Vec2((float)i - tr,(float)j - tr);			
			if (boundsRect.contains(vInPos) && (mask.getInterpolatedLinear(vInPos) < maskThresh))
			{
				float inVal = in.getInterpolatedLinear(vInPos);
				inVal *= z1;
				b(i, j) = inVal;
			}
		}
	}
	
	int tests = 0;
	float sum = 0.;

	// add differences in z from template
	a2.copy(a);
	b2.copy(b);
	a2.partialDiffX();
	b2.partialDiffX();
	for(int j=0; j < kTemplateSize; ++j)
	{
		for(int i=0; i < kTemplateSize; ++i)
		{
			if(b(i, j) > 0.)
			{
				float d = a2(i, j) - b2(i, j);
				sum += d*d;
				tests++;
			}
		}
	}

	// get RMS difference
	if(tests > 0)
	{
		r = sqrtf(sum / tests);
	}	
	return r;
}