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Expand linear operation to allow use of per-channel arrays #3303

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Anton Marsden
2022-07-23 21:33:44 +12:00
committed by Lovell Fuller
parent b9261c243c
commit 74e3f73934
10 changed files with 104 additions and 34 deletions
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10
src/operations.cc
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@@ -306,10 +306,14 @@ namespace sharp {
/*
* Calculate (a * in + b)
*/
VImage Linear(VImage image, double const a, double const b) {
if (HasAlpha(image)) {
VImage Linear(VImage image, std::vector<double> const a, std::vector<double> const b) {
size_t const bands = static_cast<size_t>(image.bands());
if (a.size() > bands) {
throw VError("Band expansion using linear is unsupported");
}
if (HasAlpha(image) && a.size() != bands && (a.size() == 1 || a.size() == bands - 1 || bands - 1 == 1)) {
// Separate alpha channel
VImage alpha = image[image.bands() - 1];
VImage alpha = image[bands - 1];
return RemoveAlpha(image).linear(a, b).bandjoin(alpha);
} else {
return image.linear(a, b);