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

lib/operation.js

@@ -415,6 +415,62 @@ function recomb (inputMatrix) {
   return this;
 }
 
+/**
+ * Transforms the image using brightness, saturation and hue rotation.
+ *
+ * @example
+ * sharp(input)
+ *   .modulate({
+ *     brightness: 2 // increase lightness by a factor of 2
+ *   });
+ *
+ * sharp(input)
+ *   .modulate({
+ *     hue: 180 // hue-rotate by 180 degrees
+ *   });
+ *
+ * // decreate brightness and saturation while also hue-rotating by 90 degrees
+ * sharp(input)
+ *   .modulate({
+ *     brightness: 0.5,
+ *     saturation: 0.5,
+ *     hue: 90
+ *   });
+ *
+ * @param {Object} [options]
+ * @param {Number} [options.brightness] Brightness multiplier
+ * @param {Number} [options.saturation] Saturation multiplier
+ * @param {Number} [options.hue] Degrees for hue rotation
+ * @returns {Sharp}
+ */
+function modulate (options) {
+  if (!is.plainObject(options)) {
+    throw is.invalidParameterError('options', 'plain object', options);
+  }
+  if ('brightness' in options) {
+    if (is.number(options.brightness) && options.brightness >= 0) {
+      this.options.brightness = options.brightness;
+    } else {
+      throw is.invalidParameterError('brightness', 'number above zero', options.brightness);
+    }
+  }
+  if ('saturation' in options) {
+    if (is.number(options.saturation) && options.saturation >= 0) {
+      this.options.saturation = options.saturation;
+    } else {
+      throw is.invalidParameterError('saturation', 'number above zero', options.saturation);
+    }
+  }
+  if ('hue' in options) {
+    if (is.integer(options.hue)) {
+      this.options.hue = options.hue % 360;
+    } else {
+      throw is.invalidParameterError('hue', 'number', options.hue);
+    }
+  }
+  return this;
+}
+
 /**
  * Decorate the Sharp prototype with operation-related functions.
  * @private
@@ -436,6 +492,7 @@ module.exports = function (Sharp) {
     threshold,
     boolean,
     linear,
-    recomb
+    recomb,
+    modulate
   });
 };