Add brightness, saturation and hue modulation #609 (#1601)

src/operations.cc

@@ -185,6 +185,21 @@ namespace sharp {
           0.0, 0.0, 0.0, 1.0));
   }
 
+  VImage Modulate(VImage image, double const brightness, double const saturation, int const hue) {
+    if (HasAlpha(image)) {
+      // Separate alpha channel
+      VImage alpha = image[image.bands() - 1];
+      return RemoveAlpha(image)
+        .colourspace(VIPS_INTERPRETATION_LCH)
+        .linear({brightness, saturation, 1}, {0, 0, static_cast<double>(hue)})
+        .bandjoin(alpha);
+    } else {
+      return image
+        .colourspace(VIPS_INTERPRETATION_LCH)
+        .linear({brightness, saturation, 1}, {0, 0, static_cast<double>(hue)});
+    }
+  }
+
   /*
    * Sharpen flat and jagged areas. Use sigma of -1.0 for fast sharpen.
    */

src/operations.h

@@ -97,6 +97,11 @@ namespace sharp {
    */
   VImage Recomb(VImage image, std::unique_ptr<double[]> const &matrix);
 
+  /*
+   * Modulate brightness, saturation and hue
+   */
+  VImage Modulate(VImage image, double const brightness, double const saturation, int const hue);
+
 }  // namespace sharp
 
 #endif  // SRC_OPERATIONS_H_

src/pipeline.cc

@@ -349,6 +349,7 @@ class PipelineWorker : public Nan::AsyncWorker {
       bool const shouldSharpen = baton->sharpenSigma != 0.0;
       bool const shouldApplyMedian = baton->medianSize > 0;
       bool const shouldComposite = !baton->composite.empty();
+      bool const shouldModulate = baton->brightness != 1.0 || baton->saturation != 1.0 || baton->hue != 0.0;
 
       if (shouldComposite && !HasAlpha(image)) {
         image = sharp::EnsureAlpha(image);
@@ -528,6 +529,10 @@ class PipelineWorker : public Nan::AsyncWorker {
         image = sharp::Recomb(image, baton->recombMatrix);
       }
 
+      if (shouldModulate) {
+        image = sharp::Modulate(image, baton->brightness, baton->saturation, baton->hue);
+      }
+
       // Sharpen
       if (shouldSharpen) {
         image = sharp::Sharpen(image, baton->sharpenSigma, baton->sharpenFlat, baton->sharpenJagged);
@@ -1210,6 +1215,9 @@ NAN_METHOD(pipeline) {
   baton->flattenBackground = AttrAsRgba(options, "flattenBackground");
   baton->negate = AttrTo<bool>(options, "negate");
   baton->blurSigma = AttrTo<double>(options, "blurSigma");
+  baton->brightness = AttrTo<double>(options, "brightness");
+  baton->saturation = AttrTo<double>(options, "saturation");
+  baton->hue = AttrTo<int32_t>(options, "hue");
   baton->medianSize = AttrTo<uint32_t>(options, "medianSize");
   baton->sharpenSigma = AttrTo<double>(options, "sharpenSigma");
   baton->sharpenFlat = AttrTo<double>(options, "sharpenFlat");

src/pipeline.h

@@ -87,6 +87,9 @@ struct PipelineBaton {
   std::vector<double> flattenBackground;
   bool negate;
   double blurSigma;
+  double brightness;
+  double saturation;
+  int hue;
   int medianSize;
   double sharpenSigma;
   double sharpenFlat;
@@ -189,6 +192,9 @@ struct PipelineBaton {
     flattenBackground{ 0.0, 0.0, 0.0 },
     negate(false),
     blurSigma(0.0),
+    brightness(1.0),
+    saturation(1.0),
+    hue(0.0),
     medianSize(0),
     sharpenSigma(0.0),
     sharpenFlat(1.0),