Ready for v2.2.0

Author: makew0rld

CHANGELOG.md

@@ -5,7 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 
-## [Unreleased]
+## [2.2.0] - 2021-05-09
 ### Added
 - Support for images with transparency (#8)
 

dither_test.go

@@ -341,12 +341,12 @@ func TestAlpha(t *testing.T) {
 	})
 	d.Mapper = Bayer(4, 4, 1)
 
-	createDitheredImage(dice, "alpha_bayer.png", d, t)
+	ditherAndCompareImage(dice, "alpha_bayer.png", d, t)
 
 	d.Mapper = nil
 	d.Matrix = FloydSteinberg
 
-	createDitheredImage(dice, "alpha_floyd-steinberg.png", d, t)
+	ditherAndCompareImage(dice, "alpha_floyd-steinberg.png", d, t)
 }
 
 // func TestDrawer(t *testing.T) {