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Add support for gamma correction #43

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Lovell Fuller
2014-08-25 21:17:13 +01:00
parent bac367b005
commit 5728efd32b
6 changed files with 85 additions and 2 deletions
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27
src/sharp.cc
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@@ -26,6 +26,7 @@ struct resize_baton {
VipsExtend extend;
bool sharpen;
std::string interpolator;
double gamma;
bool progressive;
bool without_enlargement;
VipsAccess access_method;
@@ -42,6 +43,7 @@ struct resize_baton {
gravity(0),
max(false),
sharpen(false),
gamma(0.0),
progressive(false),
without_enlargement(false),
withMetadata(false) {}
@@ -434,9 +436,9 @@ class ResizeWorker : public NanAsyncWorker {
}
}
// Try to use libjpeg shrink-on-load
// Try to use libjpeg shrink-on-load, but not when applying gamma correction
int shrink_on_load = 1;
if (inputImageType == JPEG) {
if (inputImageType == JPEG && baton->gamma == 0) {
if (shrink >= 8) {
factor = factor / 8;
shrink_on_load = 8;
@@ -469,6 +471,16 @@ class ResizeWorker : public NanAsyncWorker {
}
g_object_unref(in);
// Gamma encoding (darken)
if (baton->gamma >= 1 && baton->gamma <= 3) {
VipsImage *gamma_encoded = vips_image_new();
if (vips_gamma(shrunk_on_load, &gamma_encoded, "exponent", 1.0 / baton->gamma, NULL)) {
return resize_error(baton, shrunk_on_load);
}
g_object_unref(shrunk_on_load);
shrunk_on_load = gamma_encoded;
}
VipsImage *shrunk = vips_image_new();
if (shrink > 1) {
// Use vips_shrink with the integral reduction
@@ -567,6 +579,16 @@ class ResizeWorker : public NanAsyncWorker {
}
g_object_unref(canvased);
// Gamma decoding (brighten)
if (baton->gamma >= 1 && baton->gamma <= 3) {
VipsImage *gamma_decoded = vips_image_new();
if (vips_gamma(sharpened, &gamma_decoded, "exponent", baton->gamma, NULL)) {
return resize_error(baton, sharpened);
}
g_object_unref(sharpened);
sharpened = gamma_decoded;
}
// Always convert to sRGB colour space
VipsImage *colourspaced = vips_image_new();
vips_colourspace(sharpened, &colourspaced, VIPS_INTERPRETATION_sRGB, NULL);
@@ -702,6 +724,7 @@ NAN_METHOD(resize) {
baton->gravity = options->Get(NanNew<String>("gravity"))->Int32Value();
baton->sharpen = options->Get(NanNew<String>("sharpen"))->BooleanValue();
baton->interpolator = *String::Utf8Value(options->Get(NanNew<String>("interpolator"))->ToString());
baton->gamma = options->Get(NanNew<String>("gamma"))->NumberValue();
baton->progressive = options->Get(NanNew<String>("progressive"))->BooleanValue();
baton->without_enlargement = options->Get(NanNew<String>("withoutEnlargement"))->BooleanValue();
baton->access_method = options->Get(NanNew<String>("sequentialRead"))->BooleanValue() ? VIPS_ACCESS_SEQUENTIAL : VIPS_ACCESS_RANDOM;