Implements greyscale thresholding

test/unit/threshold.js

@@ -0,0 +1,105 @@
+'use strict';
+
+var assert = require('assert');
+
+var sharp = require('../../index');
+var fixtures = require('../fixtures');
+
+sharp.cache(0);
+
+describe('Threshold', function() {
+  it('threshold 1 jpeg', function(done) {
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .threshold(1)
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('jpeg', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-1.jpg'), data, done);
+      });
+  });
+
+  it('threshold 40 jpeg', function(done) {
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .threshold(40)
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('jpeg', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-40.jpg'), data, done);
+      });
+  });
+
+  it('threshold 128', function(done) {
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .threshold(128)
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('jpeg', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-128.jpg'), data, done);
+      });
+  });
+
+  it('threshold default jpeg', function(done) {
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .threshold()
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('jpeg', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-128.jpg'), data, done);
+      });
+  });
+
+  it('threshold default png transparency', function(done) {
+    sharp(fixtures.inputPngWithTransparency)
+      .resize(320, 240)
+      .threshold()
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('png', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-128-transparency.png'), data, done);
+      });
+  });
+
+  it('threshold default png alpha', function(done) {
+    sharp(fixtures.inputPngWithGreyAlpha)
+      .resize(320, 240)
+      .threshold()
+      .toBuffer(function(err, data, info) {
+        assert.strictEqual('png', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        fixtures.assertSimilar(fixtures.expected('threshold-128-alpha.png'), data, done);
+      });
+  });
+
+  if (sharp.format.webp.output.file) {
+    it('threshold default webp transparency', function(done) {
+      sharp(fixtures.inputWebPWithTransparency)
+        .threshold()
+        .toBuffer(function(err, data, info) {
+          assert.strictEqual('webp', info.format);
+          fixtures.assertSimilar(fixtures.expected('threshold-128-transparency.webp'), data, done);
+        });
+    });
+  }
+
+  it('invalid threshold -1', function() {
+    assert.throws(function() {
+      sharp(fixtures.inputJpg).threshold(-1);
+    });
+  });
+
+  it('invalid threshold 256', function() {
+    assert.throws(function() {
+      sharp(fixtures.inputJpg).threshold(256);
+    });
+  });
+});