feat: exposing vips_gaussnoise operation

docs/api-constructor.md

@@ -38,6 +38,10 @@ Implements the [stream.Duplex][1] class.
         -   `options.create.width` **[number][8]?** integral number of pixels wide.
         -   `options.create.height` **[number][8]?** integral number of pixels high.
         -   `options.create.channels` **[number][8]?** integral number of channels, either 3 (RGB) or 4 (RGBA).
+        -   `options.create.noise` **[Object][6]?** describes a noise to be created.
+            -    `options.create.noise.type` **[string][5]?** type of generated noise. (supported: `gaussian`)
+            -    `options.create.noise.mean` **[number][8]?** mean of pixels in generated image.
+            -    `options.create.noise.sigma` **[number][8]?** standard deviation of pixels in generated image.
         -   `options.create.background` **([string][5] \| [Object][6])?** parsed by the [color][9] module to extract values for red, green, blue and alpha.
 
 ### Examples

lib/input.js

@@ -137,22 +137,50 @@ function _createInputDescriptor (input, inputOptions, containerOptions) {
         is.object(inputOptions.create) &&
         is.integer(inputOptions.create.width) && inputOptions.create.width > 0 &&
         is.integer(inputOptions.create.height) && inputOptions.create.height > 0 &&
-        is.integer(inputOptions.create.channels) && is.inRange(inputOptions.create.channels, 3, 4) &&
-        is.defined(inputOptions.create.background)
+        is.integer(inputOptions.create.channels)
       ) {
         inputDescriptor.createWidth = inputOptions.create.width;
         inputDescriptor.createHeight = inputOptions.create.height;
         inputDescriptor.createChannels = inputOptions.create.channels;
-        const background = color(inputOptions.create.background);
-        inputDescriptor.createBackground = [
-          background.red(),
-          background.green(),
-          background.blue(),
-          Math.round(background.alpha() * 255)
-        ];
+        // Noise
+        if (is.defined(inputOptions.create.noise)) {
+          if (!is.object(inputOptions.create.noise)) {
+            throw new Error('Expected noise to be an object');
+          }
+          if (!is.inArray(inputOptions.create.noise.type, ['gaussian'])) {
+            throw new Error('Only gaussian noise is supported at the moment');
+          }
+          if (!is.inRange(inputOptions.create.channels, 1, 4)) {
+            throw is.invalidParameterError('create.channels', 'number between 1 and 4', inputOptions.create.channels);
+          }
+          inputDescriptor.createNoiseType = inputOptions.create.noise.type;
+          if (is.number(inputOptions.create.noise.mean) && is.inRange(inputOptions.create.noise.mean, 0, 10000)) {
+            inputDescriptor.createNoiseMean = inputOptions.create.noise.mean;
+          } else {
+            throw is.invalidParameterError('create.noise.mean', 'number between 0 and 10000', inputOptions.create.noise.mean);
+          }
+          if (is.number(inputOptions.create.noise.sigma) && is.inRange(inputOptions.create.noise.sigma, 0, 10000)) {
+            inputDescriptor.createNoiseSigma = inputOptions.create.noise.sigma;
+          } else {
+            throw is.invalidParameterError('create.noise.sigma', 'number between 0 and 10000', inputOptions.create.noise.sigma);
+          }
+        } else if (is.defined(inputOptions.create.background)) {
+          if (!is.inRange(inputOptions.create.channels, 3, 4)) {
+            throw is.invalidParameterError('create.channels', 'number between 3 and 4', inputOptions.create.channels);
+          }
+          const background = color(inputOptions.create.background);
+          inputDescriptor.createBackground = [
+            background.red(),
+            background.green(),
+            background.blue(),
+            Math.round(background.alpha() * 255)
+          ];
+        } else {
+          throw new Error('Expected valid noise or background to create a new input image');
+        }
         delete inputDescriptor.buffer;
       } else {
-        throw new Error('Expected valid width, height, channels and background to create a new input image');
+        throw new Error('Expected valid width, height and channels to create a new input image');
       }
     }
   } else if (is.defined(inputOptions)) {

package.json

@@ -73,7 +73,8 @@
     "Guillermo Alfonso Varela Chouciño <[email protected]>",
     "Christian Flintrup <[email protected]>",
     "Manan Jadhav <[email protected]>",
-    "Leon Radley <[email protected]>"
+    "Leon Radley <[email protected]>",
+    "alza54 <[email protected]>"
   ],
   "scripts": {
     "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node-gyp rebuild && node install/dll-copy)",

src/common.cc

@@ -109,7 +109,13 @@ namespace sharp {
       descriptor->createChannels = AttrAsUint32(input, "createChannels");
       descriptor->createWidth = AttrAsUint32(input, "createWidth");
       descriptor->createHeight = AttrAsUint32(input, "createHeight");
-      descriptor->createBackground = AttrAsVectorOfDouble(input, "createBackground");
+      if (HasAttr(input, "createNoiseType")) {
+        descriptor->createNoiseType = AttrAsStr(input, "createNoiseType");
+        descriptor->createNoiseMean = AttrAsDouble(input, "createNoiseMean");
+        descriptor->createNoiseSigma = AttrAsDouble(input, "createNoiseSigma");
+      } else {
+        descriptor->createBackground = AttrAsVectorOfDouble(input, "createBackground");
+      }
     }
     // Limit input images to a given number of pixels, where pixels = width * height
     descriptor->limitInputPixels = AttrAsUint32(input, "limitInputPixels");
@@ -318,15 +324,35 @@ namespace sharp {
     } else {
       if (descriptor->createChannels > 0) {
         // Create new image
-        std::vector<double> background = {
-          descriptor->createBackground[0],
-          descriptor->createBackground[1],
-          descriptor->createBackground[2]
-        };
-        if (descriptor->createChannels == 4) {
-          background.push_back(descriptor->createBackground[3]);
+        if (descriptor->createNoiseType == "gaussian") {
+          int const channels = descriptor->createChannels;
+          image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight);
+          std::vector<VImage> bands = {};
+          bands.reserve(channels);
+          for (int _band = 0; _band < channels; _band++) {
+            bands.push_back(image.gaussnoise(
+              descriptor->createWidth,
+              descriptor->createHeight,
+              VImage::option()->set("mean", descriptor->createNoiseMean)->set("sigma", descriptor->createNoiseSigma)));
+          }
+          image = image.bandjoin(bands);
+          image = image.cast(VipsBandFormat::VIPS_FORMAT_UCHAR);
+          if (channels < 3) {
+            image = image.colourspace(VIPS_INTERPRETATION_B_W);
+          } else {
+            image = image.colourspace(VIPS_INTERPRETATION_sRGB);
+          }
+        } else {
+          std::vector<double> background = {
+            descriptor->createBackground[0],
+            descriptor->createBackground[1],
+            descriptor->createBackground[2]
+          };
+          if (descriptor->createChannels == 4) {
+            background.push_back(descriptor->createBackground[3]);
+          }
+          image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight).new_from_image(background);
         }
-        image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight).new_from_image(background);
         image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
         imageType = ImageType::RAW;
       } else {

src/common.h

@@ -64,6 +64,9 @@ namespace sharp {
     int createWidth;
     int createHeight;
     std::vector<double> createBackground;
+    std::string createNoiseType;
+    double createNoiseMean;
+    double createNoiseSigma;
 
     InputDescriptor():
       buffer(nullptr),
@@ -82,7 +85,9 @@ namespace sharp {
       createChannels(0),
       createWidth(0),
       createHeight(0),
-      createBackground{ 0.0, 0.0, 0.0, 255.0 } {}
+      createBackground{ 0.0, 0.0, 0.0, 255.0 },
+      createNoiseMean(0.0),
+      createNoiseSigma(0.0) {}
   };
 
   // Convenience methods to access the attributes of a Napi::Object