void GetEncodedRGBAValue(const Image* img, unsigned int x, unsigned int y, const GammaCurvePtr& g, unsigned int max, unsigned int& red, unsigned int& green, unsigned int& blue, unsigned int& alpha, DitherHandler& dh, bool premul)
{
bool doPremultiply = premul && !img->IsPremultiplied() && img->HasTransparency(); // need to apply premultiplication if encoded data should be premul'ed but container content isn't
bool doUnPremultiply = !premul && img->IsPremultiplied() && img->HasTransparency(); // need to undo premultiplication if other way round
float fRed, fGreen, fBlue, fAlpha;
img->GetRGBAValue(x, y, fRed, fGreen, fBlue, fAlpha);
if (doPremultiply)
{
// Data has been stored premultiplied, but should be encoded non-premultiplied.
// No need for special handling of color components greater than alpha.
// Need to convert from premultiplied to non-premultiplied encoding.
AlphaPremultiply(fRed, fGreen, fBlue, fAlpha);
}
else if (doUnPremultiply)
{
// Data has been stored premultiplied, but should be encoded non-premultiplied.
// Clipping will happen /before/ re-multiplying with alpha (because the latter is done in the viewer), which is equivalent to clipping
// pre-multiplied components to be no greater than alpha, thereby "killing" highlights on transparent objects;
// compensate for this by boosting opacity of any exceptionally bright pixels.
float fBright = RGBColour(fRed, fGreen, fBlue).greyscale();
if (fBright > fAlpha)
fAlpha = min(1.0f, fBright);
// Need to convert from premultiplied to non-premultiplied encoding.
AlphaUnPremultiply(fRed, fGreen, fBlue, fAlpha);
}
else if (!premul)
{
// Data has been stored un-premultiplied and should be encoded that way.
// Clipping will happen /before/ multiplying with alpha (because the latter is done in the viewer), which is equivalent to clipping
// pre-multiplied components to be no greater than alpha, thereby "killing" highlights on transparent objects;
// compensate for this by boosting opacity of any exceptionally bright pixels.
float fBright = RGBColour(fRed, fGreen, fBlue).greyscale();
if (fBright > 1.0)
{
float fFactor = fBright;
if (fFactor * fAlpha > 1.0)
fFactor = 1.0/fAlpha;
// this keeps the product of alpha*color constant
fAlpha *= fFactor;
fRed /= fFactor;
fGreen /= fFactor;
fBlue /= fFactor;
}
// No need for converting between premultiplied and un-premultiplied encoding.
}
// else no need to worry about premultiplication
DitherHandler::OffsetInfo linOff, encOff;
dh.getOffset(x,y,linOff,encOff);
red = IntEncode(g,fRed + linOff.red, max, encOff.red, linOff.red);
green = IntEncode(g,fGreen + linOff.green, max, encOff.green, linOff.green);
blue = IntEncode(g,fBlue + linOff.blue, max, encOff.blue, linOff.blue);
alpha = IntEncode(fAlpha + linOff.alpha, max, encOff.alpha, linOff.alpha);
dh.setError(x,y,linOff);
}
void GetEncodedGrayAValue(const Image* img, unsigned int x, unsigned int y, const GammaCurvePtr& g, float& fGray, float& fAlpha, bool premul)
{
bool doPremultiply = premul && !img->IsPremultiplied() && img->HasTransparency(); // need to apply premultiplication if encoded data should be premul'ed but container content isn't
bool doUnPremultiply = !premul && img->IsPremultiplied() && img->HasTransparency(); // need to undo premultiplication if other way round
img->GetGrayAValue(x, y, fGray, fAlpha);
if (doPremultiply)
AlphaPremultiply(fGray, fAlpha);
else if (doUnPremultiply)
AlphaUnPremultiply(fGray, fAlpha);
// else no need to worry about premultiplication
fGray = GammaCurve::Encode(g,fGray);
}
void SetEncodedRGBAValue(Image* img, unsigned int x, unsigned int y, const GammaCurvePtr& g, float fRed, float fGreen, float fBlue, float fAlpha, bool premul)
{
bool doPremultiply = !premul && (img->IsPremultiplied() || !img->HasTransparency()); // need to apply premultiplication if encoded data isn't PM'ed but container content should be
bool doUnPremultiply = premul && !img->IsPremultiplied() && img->HasTransparency(); // need to undo premultiplication if other way round
fRed = GammaCurve::Decode(g,fRed);
fGreen = GammaCurve::Decode(g,fGreen);
fBlue = GammaCurve::Decode(g,fBlue);
if (doPremultiply)
AlphaPremultiply(fRed, fGreen, fBlue, fAlpha);
else if (doUnPremultiply)
AlphaUnPremultiply(fRed, fGreen, fBlue, fAlpha);
// else no need to worry about premultiplication
img->SetRGBAValue(x, y, fRed, fGreen, fBlue, fAlpha);
}
void SetEncodedGrayAValue(Image* img, unsigned int x, unsigned int y, const GammaCurvePtr& g, unsigned int max, unsigned int gray, unsigned int alpha, bool premul)
{
bool doPremultiply = (alpha != max) && !premul && (img->IsPremultiplied() || !img->HasTransparency()); // need to apply premultiplication if encoded data isn't PM'ed but container content should be
bool doUnPremultiply = (alpha != max) && premul && !img->IsPremultiplied() && img->HasTransparency(); // need to undo premultiplication if other way round
if (!doPremultiply && !doUnPremultiply && !img->IsIndexed() && img->GetMaxIntValue() == max && GammaCurve::IsNeutral(g))
// avoid potential re-quantization in case we have a pretty match between encoded data and container
img->SetGrayAValue(x, y, gray, alpha);
else
{
float fAlpha = IntDecode(alpha,max);
float fGray = IntDecode(g,gray,max);
if (doPremultiply)
AlphaPremultiply(fGray, fAlpha);
else if (doUnPremultiply)
AlphaUnPremultiply(fGray, fAlpha);
// else no need to worry about premultiplication
img->SetGrayAValue(x, y, fGray, fAlpha);
}
}
void AlphaUnPremultiply(RGBTColour& colour)
{
AlphaUnPremultiply(colour.red(), colour.green(), colour.blue(), colour.alpha());
}
void AlphaUnPremultiply(RGBFTColour& colour)
{
AlphaUnPremultiply(colour.red(), colour.green(), colour.blue(), colour.FTtoA());
}
void AlphaUnPremultiply(RGBColour& colour, float fAlpha)
{
AlphaUnPremultiply(colour.red(), colour.green(), colour.blue(), fAlpha);
}
void image_colour_at(const ImageData *image, DBL xcoor, DBL ycoor, RGBFTColour& colour, int *index, bool premul)
{
*index = -1;
bool doProperTransmitAll = image->data->HasTransparency() &&
!image->AllTransmitLegacyMode &&
!image->data->IsIndexed() && ( (image->AllTransmit != 0.0) || (image->AllFilter != 0.0) );
// If either source or destination uses premultiplied alpha, make sure interpolation is done in premultiplied space
// as it makes the mathematical operations cleaner -- unless the alpha channel is modulated by "transmit all" or
// "filter all", in which case we prefer non-premultiplied space.
bool getPremul = doProperTransmitAll ? (premul && image->data->IsPremultiplied()) :
(premul || image->data->IsPremultiplied());
switch(image->Interpolation_Type)
{
case NO_INTERPOLATION:
no_interpolation(image, xcoor, ycoor, colour, index, getPremul);
break;
case BICUBIC:
InterpolateBicubic(image, xcoor, ycoor, colour, index, getPremul);
break;
default:
Interp(image, xcoor, ycoor, colour, index, getPremul);
break;
}
bool havePremul = getPremul;
if (!premul && havePremul)
{
// We fetched premultiplied data, but caller expects it non-premultiplied, so we need to fix that.
// As "transmit/filter all" handling also works best on non-premultiplied data, we're doing this now.
AlphaUnPremultiply(colour.rgb(), colour.FTtoA());
havePremul = false;
}
if (doProperTransmitAll)
{
COLC imageAlpha = colour.FTtoA();
if (imageAlpha != 0.0) // No need to apply "filter/transmit all" if the image is fully transparent here anyway.
{
colour.transm() += image->AllTransmit * imageAlpha;
colour.filter() += image->AllFilter * imageAlpha;
if (havePremul)
{
// We have premultiplied data here, and the caller expects it to stay that way (otherwise we'd already
// have converted to non-premultiplied by now), so we need to fix the premultiplication of the colour
// according to our modifications to the transparency components.
COLC alphaCorrection = colour.FTtoA() / imageAlpha;
AlphaPremultiply(colour.rgb(), alphaCorrection);
}
}
}
if (premul && !havePremul)
{
// We have non-premultiplied data here, but caller expects it premultiplied, so we need to fix that
// As "transmit/filter all" handling works best on non-premultiplied data, we haven't done this earlier.
AlphaPremultiply(colour.rgb(), colour.FTtoA());
}
}