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Move background extraction into separate method (#1383)

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freezy 2018-09-24 11:00:00 +02:00 committed by Lovell Fuller
parent db2af42ee7
commit 37d385fafa
3 changed files with 44 additions and 56 deletions
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36
src/common.cc
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@ -602,4 +602,40 @@ namespace sharp {
}
}
/*
Apply the alpha channel to a given colour
*/
std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, double colour[4]) {
// Scale up 8-bit values to match 16-bit input image
double const multiplier = sharp::Is16Bit(image.interpretation()) ? 256.0 : 1.0;
// Create alphaColour colour
std::vector<double> alphaColour;
if (image.bands() > 2) {
alphaColour = {
multiplier * colour[0],
multiplier * colour[1],
multiplier * colour[2]
};
} else {
// Convert sRGB to greyscale
alphaColour = { multiplier * (
0.2126 * colour[0] +
0.7152 * colour[1] +
0.0722 * colour[2])
};
}
// Add alpha channel to alphaColour colour
if (colour[3] < 255.0 || HasAlpha(image)) {
alphaColour.push_back(colour[3] * multiplier);
}
// Ensure alphaColour colour uses correct colourspace
alphaColour = sharp::GetRgbaAsColourspace(alphaColour, image.interpretation());
// Add non-transparent alpha channel, if required
if (colour[3] < 255.0 && !HasAlpha(image)) {
image = image.bandjoin(
VImage::new_matrix(image.width(), image.height()).new_from_image(255 * multiplier));
}
return std::make_tuple(image, alphaColour);
}
} // namespace sharp

5
src/common.h
View File

@ -255,6 +255,11 @@ namespace sharp {
*/
std::vector<double> GetRgbaAsColourspace(std::vector<double> const rgba, VipsInterpretation const interpretation);
/*
Apply the alpha channel to a given colour
*/
std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, double colour[4]);
} // namespace sharp
#endif // SRC_COMMON_H_

59
src/pipeline.cc
View File

@ -421,35 +421,8 @@ class PipelineWorker : public Nan::AsyncWorker {
// Crop/embed
if (image.width() != baton->width || image.height() != baton->height) {
if (baton->canvas == Canvas::EMBED) {
// Scale up 8-bit values to match 16-bit input image
double const multiplier = sharp::Is16Bit(image.interpretation()) ? 256.0 : 1.0;
// Create background colour
std::vector<double> background;
if (image.bands() > 2) {
background = {
multiplier * baton->background[0],
multiplier * baton->background[1],
multiplier * baton->background[2]
};
} else {
// Convert sRGB to greyscale
background = { multiplier * (
0.2126 * baton->background[0] +
0.7152 * baton->background[1] +
0.0722 * baton->background[2])
};
}
// Add alpha channel to background colour
if (baton->background[3] < 255.0 || HasAlpha(image)) {
background.push_back(baton->background[3] * multiplier);
}
// Ensure background colour uses correct colourspace
background = sharp::GetRgbaAsColourspace(background, image.interpretation());
// Add non-transparent alpha channel, if required
if (baton->background[3] < 255.0 && !HasAlpha(image)) {
image = image.bandjoin(
VImage::new_matrix(image.width(), image.height()).new_from_image(255 * multiplier));
}
std::tie(image, background) = sharp::ApplyAlpha(image, baton->background);
// Embed
@ -511,35 +484,9 @@ class PipelineWorker : public Nan::AsyncWorker {
// Extend edges
if (baton->extendTop > 0 || baton->extendBottom > 0 || baton->extendLeft > 0 || baton->extendRight > 0) {
// Scale up 8-bit values to match 16-bit input image
double const multiplier = sharp::Is16Bit(image.interpretation()) ? 256.0 : 1.0;
// Create background colour
std::vector<double> background;
if (image.bands() > 2) {
background = {
multiplier * baton->background[0],
multiplier * baton->background[1],
multiplier * baton->background[2]
};
} else {
// Convert sRGB to greyscale
background = { multiplier * (
0.2126 * baton->background[0] +
0.7152 * baton->background[1] +
0.0722 * baton->background[2])
};
}
// Add alpha channel to background colour
if (baton->background[3] < 255.0 || HasAlpha(image)) {
background.push_back(baton->background[3] * multiplier);
}
// Ensure background colour uses correct colourspace
background = sharp::GetRgbaAsColourspace(background, image.interpretation());
// Add non-transparent alpha channel, if required
if (baton->background[3] < 255.0 && !HasAlpha(image)) {
image = image.bandjoin(
VImage::new_matrix(image.width(), image.height()).new_from_image(255 * multiplier));
}
std::tie(image, background) = sharp::ApplyAlpha(image, baton->background);
// Embed
baton->width = image.width() + baton->extendLeft + baton->extendRight;
baton->height = image.height() + baton->extendTop + baton->extendBottom;