Organise script

foo.py

 from PIL import Image
+import sys
 
-def p(a):
+def mapColors(rgb):
+    return tuple(round(v / 255.0) for v in rgb)
+
+def encode(a):
     result = 0
     for i, rgb in enumerate(a):
-        r,g,b = [round(v / 255.0) for v in rgb]
+        r,g,b = rgb
         result |= r << i * 3
         result |= g << i * 3 + 1
         result |= b << i * 3 + 2
-    return result
+    return hex(result)
+
+if len(sys.argv) != 2:
+    print("Missing file name argument", file=sys.stderr)
+    sys.exit(1)
 
-img = Image.open("20px-color.bmp").convert('RGB')
+filename = sys.argv[1]
+img = Image.open(filename).convert('RGB')
 width, height = img.size
-pixels = [p([img.getpixel((x,y)) for y in range(height)]) for x in range(width)]
+pixels = [[mapColors(img.getpixel((x,y))) for y in range(height)] for x in range(width)]
+
 
-array = "{" + ",".join([hex(p) for p in pixels]) + "}"
+array = "{" + ",".join([encode(p) for p in pixels]) + "}"
 
 code = """uint64_t[{width}] pixels = {array};