Enhance recombination algorithm to support 4x4 matrices (#4145)

lib/constructor.js

@@ -346,6 +346,7 @@ const Sharp = function (input, options) {
     timeoutSeconds: 0,
     linearA: [],
     linearB: [],
+
     // Function to notify of libvips warnings
     debuglog: warning => {
       this.emit('warning', warning);

lib/index.d.ts

@@ -571,11 +571,11 @@ declare namespace sharp {
 
         /**
          * Recomb the image with the specified matrix.
-         * @param inputMatrix 3x3 Recombination matrix
+         * @param inputMatrix 3x3 Recombination matrix or 4x4 Recombination matrix
          * @throws {Error} Invalid parameters
          * @returns A sharp instance that can be used to chain operations
          */
-        recomb(inputMatrix: Matrix3x3): Sharp;
+        recomb(inputMatrix: Matrix3x3 | Matrix4x4): Sharp;
 
         /**
          * Transforms the image using brightness, saturation, hue rotation and lightness.
@@ -1730,6 +1730,7 @@ declare namespace sharp {
 
     type Matrix2x2 = [[number, number], [number, number]];
     type Matrix3x3 = [[number, number, number], [number, number, number], [number, number, number]];
+    type Matrix4x4 = [[number, number, number, number], [number, number, number, number], [number, number, number, number], [number, number, number, number]];
 }
 
 export = sharp;

lib/operation.js

@@ -787,24 +787,23 @@ function linear (a, b) {
  *     // With this example input, a sepia filter has been applied
  *   });
  *
- * @param {Array<Array<number>>} inputMatrix - 3x3 Recombination matrix
+ * @param {Array<Array<number>>} inputMatrix - 3x3 Recombination matrix or 4x4 Recombination matrix
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
  */
 function recomb (inputMatrix) {
-  if (!Array.isArray(inputMatrix) || inputMatrix.length !== 3 ||
-      inputMatrix[0].length !== 3 ||
-      inputMatrix[1].length !== 3 ||
-      inputMatrix[2].length !== 3
-  ) {
-    // must pass in a kernel
+  if (!Array.isArray(inputMatrix)) {
+    throw new Error('Invalid recombination matrix');
+  }
+  if (inputMatrix.length !== 3 && inputMatrix.length !== 4) {
     throw new Error('Invalid recombination matrix');
   }
-  this.options.recombMatrix = [
-    inputMatrix[0][0], inputMatrix[0][1], inputMatrix[0][2],
-    inputMatrix[1][0], inputMatrix[1][1], inputMatrix[1][2],
-    inputMatrix[2][0], inputMatrix[2][1], inputMatrix[2][2]
-  ].map(Number);
+  const recombMatrix = inputMatrix.flat().map(Number);
+  if (recombMatrix.length !== 9 && recombMatrix.length !== 16) {
+    throw new Error('Invalid recombination matrix');
+  }
+
+  this.options.recombMatrix = recombMatrix;
   return this;
 }
 

src/operations.cc

@@ -183,19 +183,25 @@ namespace sharp {
    * Recomb with a Matrix of the given bands/channel size.
    * Eg. RGB will be a 3x3 matrix.
    */
-  VImage Recomb(VImage image, std::unique_ptr<double[]> const &matrix) {
-    double *m = matrix.get();
+  VImage Recomb(VImage image, std::vector<double> const& matrix) {
+    const double* m = matrix.data();
+    void *matrix_data = const_cast<void*>(static_cast<const void*>(m));
     image = image.colourspace(VIPS_INTERPRETATION_sRGB);
-    return image
-      .recomb(image.bands() == 3
-        ? VImage::new_from_memory(
-          m, 9 * sizeof(double), 3, 3, 1, VIPS_FORMAT_DOUBLE
-        )
-        : VImage::new_matrixv(4, 4,
-          m[0], m[1], m[2], 0.0,
-          m[3], m[4], m[5], 0.0,
-          m[6], m[7], m[8], 0.0,
-          0.0, 0.0, 0.0, 1.0));
+    if (matrix.size() == 9) {
+      return image
+        .recomb(image.bands() == 3
+          ? VImage::new_from_memory(
+            matrix_data, 9 * sizeof(double), 3, 3, 1, VIPS_FORMAT_DOUBLE
+          )
+          : VImage::new_matrixv(4, 4,
+            m[0], m[1], m[2], 0.0,
+            m[3], m[4], m[5], 0.0,
+            m[6], m[7], m[8], 0.0,
+            0.0, 0.0, 0.0, 1.0));
+    } else {
+      return image
+        .recomb(VImage::new_from_memory(matrix_data, 16 * sizeof(double), 4, 4, 1, VIPS_FORMAT_DOUBLE));
+    }
   }
 
   VImage Modulate(VImage image, double const brightness, double const saturation,

src/operations.h

@@ -95,7 +95,7 @@ namespace sharp {
    * Recomb with a Matrix of the given bands/channel size.
    * Eg. RGB will be a 3x3 matrix.
    */
-  VImage Recomb(VImage image, std::unique_ptr<double[]> const &matrix);
+  VImage Recomb(VImage image, std::vector<double> const &matrix);
 
   /*
    * Modulate brightness, saturation, hue and lightness

src/pipeline.cc

@@ -609,7 +609,7 @@ class PipelineWorker : public Napi::AsyncWorker {
       }
 
       // Recomb
-      if (baton->recombMatrix != NULL) {
+      if (!baton->recombMatrix.empty()) {
         image = sharp::Recomb(image, baton->recombMatrix);
       }
 
@@ -1613,10 +1613,11 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
     }
   }
   if (options.Has("recombMatrix")) {
-    baton->recombMatrix = std::unique_ptr<double[]>(new double[9]);
     Napi::Array recombMatrix = options.Get("recombMatrix").As<Napi::Array>();
-    for (unsigned int i = 0; i < 9; i++) {
-       baton->recombMatrix[i] = sharp::AttrAsDouble(recombMatrix, i);
+    unsigned int matrixElements = recombMatrix.Length();
+    baton->recombMatrix.resize(matrixElements);
+    for (unsigned int i = 0; i < matrixElements; i++) {
+      baton->recombMatrix[i] = sharp::AttrAsDouble(recombMatrix, i);
     }
   }
   baton->colourspacePipeline = sharp::AttrAsEnum<VipsInterpretation>(

src/pipeline.h

@@ -223,7 +223,7 @@ struct PipelineBaton {
   VipsForeignDzDepth tileDepth;
   std::string tileId;
   std::string tileBasename;
-  std::unique_ptr<double[]> recombMatrix;
+  std::vector<double> recombMatrix;
 
   PipelineBaton():
     input(nullptr),

test/fixtures/index.js

@@ -139,6 +139,7 @@ module.exports = {
 
   testPattern: getPath('test-pattern.png'),
 
+  inputPngWithTransparent: getPath('d.png'),
   // Path for tests requiring human inspection
   path: getPath,
 

test/types/sharp.test-d.ts

@@ -295,6 +295,13 @@ sharp('input.gif')
     [0.2392, 0.4696, 0.0912],
   ])
 
+  .recomb([
+    [1,0,0,0],
+    [0,1,0,0],
+    [0,0,1,0],
+    [0,0,0,1],
+  ])
+
   .modulate({ brightness: 2 })
   .modulate({ hue: 180 })
   .modulate({ lightness: 10 })

test/unit/recomb.js

@@ -121,6 +121,29 @@ describe('Recomb', function () {
       });
   });
 
+  it('applies opacity 30% to the image', function (done) {
+    const output = fixtures.path('output.recomb-opacity.png');
+    sharp(fixtures.inputPngWithTransparent)
+      .recomb([
+        [1, 0, 0, 0],
+        [0, 1, 0, 0],
+        [0, 0, 1, 0],
+        [0, 0, 0, 0.3]
+      ])
+      .toFile(output, function (err, info) {
+        if (err) throw err;
+        assert.strictEqual('png', info.format);
+        assert.strictEqual(48, info.width);
+        assert.strictEqual(48, info.height);
+        fixtures.assertMaxColourDistance(
+          output,
+          fixtures.expected('d-opacity-30.png'),
+          17
+        );
+        done();
+      });
+  });
+
   describe('invalid matrix specification', function () {
     it('missing', function () {
       assert.throws(function () {