gistfile1.rb

# palettegen.rb
# Copyright 2008 Michael Yacavone, myacavone at gmail.com
# Released under the MIT license ("do whatever you want")
# http://www.opensource.org/licenses/mit-license.php
# Would love to receive improvement patches!

# Version 1.0
# February 18, 2007

# Version 1.1
# January 11, 2014

require 'RMagick'
include Magick

$just_print = false
if ARGV.length == 2
  $just_print = true
  aperture = Integer(ARGV[1])
elsif ARGV.length != 4
  puts "  Usage: ruby palettegen.rb InputImage OutputImage SwatchSize ApertureSize"
  puts "  Example: ruby palettegen.rb Ocean.jpg OceanPalette.jpg 50 100"
  puts "    Palettegen generates a 9x5 color palette from an input image."
  puts "    SwatchSize is the output color-swatch size."
  puts "    ApertureSize is the 'lens' size that picks up color from the image."
  puts "    ApertureSize is at the end because you may want to experiment to "
  puts "    find the optimal size."
  exit
end

# Read the image file 
img = Magick::Image::read(ARGV[0]).first


if not $just_print
  # Set size of color swatches
  $swatch = Integer(ARGV[2])

  # Set the aperture of the target samples
  aperture = Integer(ARGV[3])
  # Create shades for blending  
  $black = Magick::Image.new($swatch, $swatch) { self.background_color = '#000000' }
  $white = Magick::Image.new($swatch, $swatch) { self.background_color = '#ffffff' }
end

# Get the x/y coordinates of the five sample locations,
# based on the rule of thirds and the center. This awesome idea via 
# Shelley Powers at http://burningbird.net/php/photographs.phps
topy = (img.rows / 3)
bottomy = ((img.rows / 3) * 2);
leftx = (img.columns / 3);
rightx = ((img.columns / 3) * 2);
centery = (img.rows / 2);
centerx = (img.columns / 2);


# Create an imagelist to hold the blends
blendedImages = Magick::ImageList.new

# Blend each of five samples with a black or white shade, in various percentages, to generate a palette.
# Process: at each x/y coordinate, crop out a rect based on the aperture size,
# quantize this rect down to a single color,
# set the background color to the quantized color,
# put each blended image into the imagelist.

def printColor(src)
  color = src.pixel_color(1,1)
  puts "#{color.red.to_s(16)}:#{color.green.to_s(16)}:#{color.blue.to_s(16)}"
end

def addImage(src, images)
  src = Magick::Image.new($swatch, $swatch) { self.background_color = src.pixel_color(1, 1) }
  images << $black.blend(src, 0.2)
  images << $black.blend(src, 0.4)
  images << $black.blend(src, 0.6)
  images << $black.blend(src, 0.8)
  images << src 
  images << $white.blend(src, 0.8)
  images << $white.blend(src, 0.6)
  images << $white.blend(src, 0.4)
  images << $white.blend(src, 0.2)
end

def processImage(src, images)
  if $just_print
    printColor(src)
  else
    addImage(src, images)
  end
end


# The following is total brute force; could use some block'd elegence....  
src = img.crop(leftx, topy, aperture, aperture).quantize(1)
processImage(src, blendedImages)

src = img.crop(rightx, topy, aperture, aperture).quantize(1)
processImage(src, blendedImages)

src = img.crop(leftx, bottomy, aperture, aperture).quantize(1)
processImage(src, blendedImages)

src = img.crop(rightx, bottomy, aperture, aperture).quantize(1)
processImage(src, blendedImages)

src = img.crop(centerx, centery, aperture, aperture).quantize(1)
processImage(src, blendedImages)
                 
# Positon blended images on a canvas.
# The tile is hard-coded to fit the nine swatches for each of the five samples.
# The geometry sets the gap between $swatches.
if blendedImages.size > 0
  montage = blendedImages.montage {
    self.tile = "9x5"
    self.geometry = "+2+2"
    self.background_color = "black"
  }

  # Write file to disk
  montage.write(ARGV[1])
end

# To-do:
# Use blocks instead of the brute force swatch creation.
# Write text onto the image with original file name, aperture size, and maybe hex color values?
# Specify a global offset to the five target samples in case you want to move the sample targets around the image.
# Build a UI and make it a web app.