Added BW Mode, Transparency Support

README.md

@@ -0,0 +1,15 @@
+# qwer
+
+This script accomplishes [Floyd-Steinberg dithering](https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering) in Python. Takes inputs as bitmap or png files. 
+
+It is extremely useful for compression, especially the 1-bit ``--bw`` mode. In testing, this script in black and white mode was able to reduce 181x215 pixel image from 53.2KB to 4.89KB, albeit with all colour lost. Colour (default) mode reduced the image to 23.7KB.
+
+## Usage
+
+To use the script in colour, write as follows: ``python main.py lena.bmp -o lena.png``
+
+If you wish to use the script in black and white: ``python main.py -o lena.png --bw``
+
+## Creds
+
+This script was originally created by [trimailov](https://github.com/trimailov). [lesageethan](https://github.com/lesageethan) added the 1-bit mode and transparency support.

main.py

@@ -8,7 +8,8 @@
 
 
 class Dither():
-    def __init__(self, path, algorithm=None, output=None):
+    def __init__(self, path, algorithm=None, output=None, bw=False):
+        self.bw = bw
         self.path = self.get_path(path)
         self.algorithm = algorithm
         self.output = output
@@ -54,11 +55,19 @@ def floyd_steinberg_dither(self, image_file):
         find_closest_palette_color(oldpixel) = floor(oldpixel / 256)
         """
 
-        new_img = Image.open(image_file)
+        new_img = Image.open(image_file).convert('RGBA')
+
+        # Turn transparent pixels white
+        background = Image.new("RGBA", new_img.size, "WHITE")
+        background.paste(new_img, mask=new_img)
+
+        # Convert to black and white if instructed
+        if self.bw:
+            new_img = new_img.convert('L')
 
         new_img = new_img.convert('RGB')
-        pixel = new_img.load()
 
+        pixel = new_img.load()
         x_lim, y_lim = new_img.size
 
         for y in range(1, y_lim):
@@ -104,6 +113,9 @@ def floyd_steinberg_dither(self, image_file):
                     pixel[x+1, y+1] = (red, green, blue)
 
         if self.output:
+            # Set colour to 1-bit if black and white is true
+            if self.bw:
+                new_img = new_img.convert("1")
             new_img.save(self.output)
         else:
             new_img.show()
@@ -113,9 +125,9 @@ def main():
     parser = ArgumentParser(description="Image dithering in python")
     parser.add_argument("image_path", help="input image location")
     parser.add_argument("-o", help="output image location")
+    parser.add_argument("--bw", help="black and white", action="store_true")
     args = parser.parse_args()
 
-    if args.image_path and not args.o:
-        Dither(args.image_path)
-    elif args.image_path and args.o:
-        Dither(args.image_path, output=args.o)
+    Dither(args.image_path, output=args.o, bw=args.bw)
+
+main()