Add support for squashing TIFF output to 1-bit (#783)

lib/constructor.js

@@ -171,6 +171,7 @@ const Sharp = function (input, options) {
     tiffQuality: 80,
     tiffCompression: 'jpeg',
     tiffPredictor: 'none',
+    tiffSquash: false,
     tileSize: 256,
     tileOverlap: 0,
     // Function to notify of queue length changes

lib/output.js

@@ -213,6 +213,7 @@ function webp (options) {
  * @param {Boolean} [options.force=true] - force TIFF output, otherwise attempt to use input format
  * @param {Boolean} [options.compression='jpeg'] - compression options: lzw, deflate, jpeg
  * @param {Boolean} [options.predictor='none'] - compression predictor options: none, horizontal, float
+ * @param {Boolean} [options.squash=false] - squash 8-bit images down to 1 bit
  * @returns {Sharp}
  * @throws {Error} Invalid options
  */
@@ -224,6 +225,13 @@ function tiff (options) {
       throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
     }
   }
+  if (is.object(options) && is.defined(options.squash)) {
+    if (is.bool(options.squash)) {
+      this.options.tiffSquash = options.squash;
+    } else {
+      throw new Error('Invalid Value for squash ' + options.squash + ' Only Boolean Values allowed for options.squash.');
+    }
+  }
   // compression
   if (is.defined(options) && is.defined(options.compression)) {
     if (is.string(options.compression) && is.inArray(options.compression, ['lzw', 'deflate', 'jpeg', 'none'])) {