1 files changed, 24 insertions, 0 deletions
diff --git a/share/extensions/color_blackandwhite.py b/share/extensions/color_blackandwhite.py
new file mode 100755
index 0000000..e5e65b2
--- /dev/null
+++ b/share/extensions/color_blackandwhite.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+"""To black and white"""
+
+import inkex
+
+
+class BlackAndWhite(inkex.ColorExtension):
+    """Convert colours to black and white"""
+
+    def add_arguments(self, pars):
+        pars.add_argument(
+            "-t", "--threshold", type=int, default=127, help="Threshold Color Level"
+        )
+
+    def modify_color(self, name, color):
+        # ITU-R Recommendation BT.709 (NTSC and PAL)
+        # l = 0.2125 * r + 0.7154 * g + 0.0721 * b
+        lum = 0.299 * color.red + 0.587 * color.green + 0.114 * color.blue
+        grey = 255 if lum > self.options.threshold else 0
+        return inkex.Color((grey, grey, grey))
+
+
+if __name__ == "__main__":
+    BlackAndWhite().run()