Merge pull request #15 from ehashman/bugfix

Optimize palette selection for non-indexed images

README.md

@@ -150,3 +150,4 @@ LEGO® is a registered trademark of The Lego Group.
 
 PERLER BEADS is a trademark of Stitch Acquisition Group. 
 
+Aurora test image (`test_image.jpg`) by Jonathan Bean from Unsplash: https://unsplash.com/photos/Ejpx_sdKEKo

ih/chart.py

@@ -53,17 +53,17 @@ def preprocess_image(
     scale=DEFAULT["scale"],
     guidelines=DEFAULT["guidelines"],
 ):
+    # Reduce palette to max 256 colors
+    reduced_palette = palette.reduce_palette(palette=pal, image=im)
+    palette_image = palette.get_palette_image(reduced_palette)
+    im = im.resize((int(im.width / scale), int(im.height / scale)))
+
     # Remove black transparency issues with this one weird trick.
     alpha = im.convert("RGBA").split()[-1]
     bg = Image.new("RGBA", im.size, (255, 255, 255, 255))
     bg.paste(im, mask=alpha)
     im = bg
 
-    # Reduce palette
-    reduced_palette = palette.reduce_palette(palette=pal, image=im)  # cap palette size at 256
-    palette_image = palette.get_palette_image(reduced_palette)
-    im = im.resize((int(im.width / scale), int(im.height / scale)))
-
     im = (
         im.convert("RGB")
         .convert("P", palette=Image.ADAPTIVE, colors=colors)

ih/palette.py

@@ -91,11 +91,12 @@ def reduce_palette(palette, image):
     best_colours = set()
 
     # Get image palette in RGB triplets
-    my_colours = [x[0:3] for x in image.getdata()]
+    im = image.convert("P", palette=Image.ADAPTIVE, colors=256)
+    image_palette = im.getpalette()
+    my_colours = []
+    for i in range (0, len(image_palette), 3):
+        my_colours.append(image_palette[i:i+3])
 
-    # Larger palettes may take some time, so let 'em know.
-    if len(my_colours) > 12:
-        print("Processing...")
     # Get nearest colour https://stackoverflow.com/a/22478139
     tree = sp.KDTree(palette_triplets)
     for colour in my_colours:

tests/test_cli.py

@@ -7,9 +7,9 @@
 TEST_HTML = TEST_IMAGE.split(".")[0] + ".html"
 
 
-def runner(args, output=TEST_HTML, print_output=False):
+def runner(args, output=TEST_HTML, print_output=False, image=TEST_IMAGE):
     runner = CliRunner()
-    result = runner.invoke(main, [TEST_IMAGE] + args)
+    result = runner.invoke(main, [image] + args)
     if print_output:
         print(result.output)
     assert result.exit_code == 0
@@ -27,6 +27,7 @@ def test_render():
 def test_palettes():
     for p in palette.PALETTES:
         runner(["-p", p])
+        runner(["-p", p, "-s", "25"], image="test_image.jpg")
 
 
 def test_guidelines():
@@ -51,3 +52,7 @@ def test_term():
 
 def test_term_render():
     runner(["-o", "term", "-r"], output="ih version", print_output=True)
+    runner(["-o", "term", "-r", "-s", "25"],
+           output="ih version",
+           print_output=True,
+           image="test_image.jpg")