Dithering for newspaper look

Author: monkstone

external_library/java/image_processing/dithering.rb

@@ -0,0 +1,56 @@
+# Example for dithering an image to get a retro look.
+#
+# Use the mouse wheel to change the dithering algorithm
+# and press spacebar to show it in gray scale for the perfect
+# retro look.
+#
+# Author: Nick 'Milchreis' Müller
+load_library :ImageProcessing
+java_import 'milchreis.imageprocessing.Dithering'
+java_import 'milchreis.imageprocessing.Grayscale'
+
+attr_reader :my_image, :processed, :label, :index
+
+def settings
+  size(550, 550)
+end
+
+def setup
+  sketch_title 'Dithering'
+  @index = 0
+  @my_image = load_image(data_path('example.jpg'))
+end
+
+def draw
+  @processed = my_image
+  @label = ''
+  if key_pressed? && key == ' '
+    @processed = Grayscale.apply(processed)
+  end
+  return image(my_image, 0, 0) if mouse_pressed?
+  case index
+  when -1
+    @processed = Dithering.apply(processed)
+    @label = 'BAYER_4x4 on default'
+  when 0
+    @processed = Dithering.apply(processed, Dithering::Algorithm::BAYER_2x2)
+    @label = 'BAYER_2x2'
+  when 1
+    @processed = Dithering.apply(processed, Dithering::Algorithm::BAYER_4x4)
+    @label = 'BAYER_4x4'
+  when 2
+    @processed = Dithering.apply(processed, Dithering::Algorithm::BAYER_8x8)
+    @label = 'BAYER_8x8'
+  end
+  image(processed, 0, 0)
+  fill(0)
+  text(label, width / 2 - text_width(label) / 2, 30)
+end
+
+def mouseWheel(event)
+  @index += event.get_count
+
+  if index >= Dithering::Algorithm.values.length
+    @index = -1
+  end
+end