Add grayscale.py.

grayscale.py

@@ -0,0 +1,21 @@
+import PIL.Image
+import sys
+
+from voussoirkit import pathclass
+from voussoirkit import pipeable
+from voussoirkit import winglob
+
+def main(argv):
+    for pattern in pipeable.go(argv, strip=True, skip_blank=True):
+        filenames = winglob.glob(pattern)
+        for filename in filenames:
+            filename = pathclass.Path(filename)
+            if filename.replace_extension('').basename.endswith('_gray'):
+                continue
+            new_filename = filename.replace_extension('').absolute_path + '_gray' + filename.dot_extension
+            print(f'{filename.basename} -> {new_filename.basename}')
+            image = PIL.Image.open(filename.absolute_path).convert('LA')
+            image.save(new_filename)
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))