Ensure create has correct bit depth and colourspace #3139

lib/operation.js

@@ -420,6 +420,17 @@ function gamma (gamma, gammaOut) {
 
 /**
  * Produce the "negative" of the image.
+ *
+ * @example
+ * const output = await sharp(input)
+ *   .negate()
+ *   .toBuffer();
+ *
+ * @example
+ * const output = await sharp(input)
+ *   .negate({ alpha: false })
+ *   .toBuffer();
+ *
  * @param {Object} [options]
  * @param {Boolean} [options.alpha=true] Whether or not to negate any alpha channel
  * @returns {Sharp}