Parametrize dither patterns as command-line argument

convert.py

@@ -25,6 +25,9 @@ def main():
         "--lookahead", type=int, default=4,
         help=("How many pixels to look ahead to compensate for NTSC colour "
               "artifacts."))
+    parser.add_argument('--dither', type=str,
+                        choices=list(dither_pattern.PATTERNS.keys()),
+                        default=dither_pattern.DEFAULT_PATTERN)
     args = parser.parse_args()
 
     palette = palette_py.Palette()
@@ -34,9 +37,7 @@ def main():
     image = image_py.open(screen.X_RES, screen.Y_RES, args.input)
     # image_rgb.show()
 
-    # dither = dither_pattern.FloydSteinbergDither()
-    # dither = dither_pattern.BuckelsDither()
-    dither = dither_pattern.JarvisDither()
+    dither = dither_pattern.PATTERNS[args.dither]()
 
     start = time.time()
     output_4bit, output_rgb = dither_pyx.dither_image(

dither_pattern.py

@@ -7,6 +7,7 @@ class DitherPattern:
 
 
 class FloydSteinbergDither(DitherPattern):
+    """Floyd-Steinberg dither."""
     # 0 * 7
     # 3 5 1
     PATTERN = np.array(((0, 0, 7), (3, 5, 1)),
@@ -16,6 +17,7 @@ class FloydSteinbergDither(DitherPattern):
 
 
 class BuckelsDither(DitherPattern):
+    """Default dither from bmp2dhr."""
     # 0 * 2 1
     # 1 2 1 0
     # 0 1 0 0
@@ -25,6 +27,8 @@ class BuckelsDither(DitherPattern):
 
 
 class JarvisDither(DitherPattern):
+    """Jarvis dithering."""
+
     # 0 0 X 7 5
     # 3 5 7 5 3
     # 1 3 5 3 1
@@ -32,3 +36,12 @@ class JarvisDither(DitherPattern):
                        dtype=np.float32).reshape(3, 5, 1) / np.float32(48)
     ORIGIN = (0, 2)
 
+
+PATTERNS = {
+    'floyd': FloydSteinbergDither,
+    'floyd-steinberg': FloydSteinbergDither,
+    'buckels': BuckelsDither,
+    'jarvis': JarvisDither
+}
+
+DEFAULT_PATTERN = 'jarvis'