Add kodak effect example script and demo images in README

Author: peterc

README.md

@@ -85,6 +85,17 @@ PureJPEG.encode(source,
 
 See [CREATIVE.md](CREATIVE.md) for detailed examples of the creative encoding options.
 
+<table>
+<tr>
+<td align="center"><strong>Normal (q20)</strong></td>
+<td align="center"><strong>Scrambled quantization (q20)</strong></td>
+</tr>
+<tr>
+<td><img src="examples/peppers.jpg" width="360"></td>
+<td><img src="examples/peppers-funky.jpg" width="360"></td>
+</tr>
+</table>
+
 Each stage of the JPEG pipeline is a separate module, so individual components (DCT, quantization, Huffman coding) can be replaced or extended independently which is kinda my plan here as I made this to play around with effects.
 
 ## Decoding (reading JPEGs!)

examples/kodak.rb

@@ -0,0 +1,16 @@
+#!/usr/bin/env ruby
+require_relative "../lib/pure_jpeg"
+
+if ARGV.length < 1
+  $stderr.puts "Usage: #{$0} INPUT.jpg [OUTPUT.jpg] [quality]"
+  exit 1
+end
+
+input = ARGV[0]
+output = ARGV[1] || input.sub(/(\.\w+)$/, '_kodak\1')
+quality = (ARGV[2] || 20).to_i
+
+image = PureJPEG.read(input)
+PureJPEG.encode(image, quality: quality, scramble_quantization: true).write(output)
+
+puts "#{input} -> #{output} (#{File.size(output)} bytes, q#{quality}, scrambled quantization)"