#!/home/software/ruby-1.8.7/bin/ruby -w
require 'RMagick'
img = Magick::Image.read('images/Flower_Hat.jpg').first
# Convert to grayscale
sketch = img.quantize(256, Magick::GRAYColorspace)
# Apply histogram equalization
sketch = sketch.equalize
# Sketch, then dissolve 25% of the original back in
sketch = sketch.sketch(0, 10, 135)
img = img.dissolve(sketch, 0.75, 0.25)
img.write('sketch.jpg')