Added random dither and updated readme

README.md

@@ -14,7 +14,7 @@ lid [option]... [source path] [output name]
 
 Options:<br>
 -f = output format, defaults to the recommended setting: png<br>
--m = mode, available: o4, o9, e. default: o4.<br>
+-m = mode, available: o4, o9, e, t, r, a. default: o4.<br>
 -q = quality (0 - 100), defaults to 90, only affects jpeg/jpg<br>
 -t = threshold (0 - 255), defaults to image average level. only affects dither mode 't'
 
@@ -28,6 +28,9 @@ Lid works best outputting png files from any input. You will get the smallest fi
 #### t
 This is the lowest quality mode. It produces the smallest file, but at the cost of most detail.
 
+#### r
+Random dithering produces a fairly large file (comparable to error diffusion), without moving much closer to photographic quality. However, it does provide an interesting effect.
+
 #### o4
 This mode is a noticable difference from the stark two tone appearance of threashold mode. The appearance 'gray' areas make for a slightly more photographic image.
 

lid

@@ -7,6 +7,7 @@
 from PIL import Image
 import sys
 import os, os.path
+from random import randint
 
 class Dither:
     def __init__(self, data):
@@ -88,7 +89,14 @@ class Dither:
 
 
     def random_dither(self):
-        pass
+        print("Dither method: random\033[?25l".format(self.threshold))
+        for row in range(0, self.height):
+            for col in range(0, self.width):
+                px = self.get_pixel(col, row)
+                rand = randint(1,255)
+                self.new_pixels[col, row] = int(px > rand)
+                self.update_progress()
+        self.save_file()
 
     def error_diffusion_dither(self):
         i = self.source_image.load()
@@ -161,7 +169,7 @@ def display_help():
 
     options:
     -f          output format. defaults to: png (recommended)
-    -m          dither mode. defaults to: o4. other options: e, o9
+    -m          dither mode. defaults to: o4. other options: e, o9, t, r, a
     -q          image quality. defaults to: 90. only has effect on png/jpg
     -t          threshold. default: image average tone. onls has effect in mode 't'
 
@@ -179,6 +187,8 @@ def display_help():
 
     the quality flag mostly seems to effect jpegs and does not do a whole
     heap to PNG files, but play around with it as mileage may vary.
+
+    to output an image with each type of dither, use mode a
     """
     print(helptext)
 
@@ -226,8 +236,8 @@ def parse_input():
     elif argmap["-f"] == "jpg":
         argmap["-f"] = "jpeg"
 
-    if not argmap["-m"] in ["o4", "e", "o9", "t", "a"]:
-        print("lid error: invalid dither mode provided for -m. Options: o4, o9, e. Default: o4")
+    if not argmap["-m"] in ["o4", "e", "o9", "t", "r", "a"]:
+        print("lid error: invalid dither mode provided for -m. Options: o4, o9, e, t, r, a. Default: o4")
         return None
 
     try:
@@ -267,6 +277,8 @@ if __name__ == "__main__":
             d.error_diffusion_dither()
         elif request["-m"] == "t":
             d.threshold_dither()
+        elif request["-m"] == "r":
+            d.random_dither()
         elif request["-m"] == "a":
             name = request["out"]
             request["out"] = name + "_o4"
@@ -281,6 +293,9 @@ if __name__ == "__main__":
             request["out"] = name + "_e"
             d4 = Dither(request)
             d4.error_diffusion_dither()
+            request["out"] = name + "_r"
+            d4 = Dither(request)
+            d4.random_diffusion_dither()
         else:
             print("Unknown mode flag")
             sys.exit(2)