使用RMagick处理图片

require 'RMagick'
require 'open-uri'
require 'rexml/document'
include REXML

class WI
  def initialize()
    @url = "http://rorbuilder.info/r/colour_lookup.xml?passthru=1"
  end

  def colour(image_file_name)
    iod = Magick::Image.read(image_file_name).first
    rows = iod.rows
    cols = iod.columns
    doc = Document.new(open(@url, "UserAgent" => "Ruby-ColourLookup reader").read)
    html_colours = doc.root.elements.to_a("records/colour")
    a = html_colours.map do |c|
      [c.text('hexcode'), [c.text('name'), c.text('rgb').split(',').map {|x| x.to_i}]]
    end
    name_lookup = Hash[*a.inject([]){|r,x| r + x}]
    lookup = html_colours.map do |x|
      [x.text('hexcode'), x.text('rgb').split(',').map {|x| x.to_i}]
    end
    rows.times do |y|
      pixels = iod.get_pixels(0, y, cols, 1)
      colour_pixels = pixels.map do |c|
        [c.red, c.green, c.blue].map{|x| "%02x" % Math.sqrt(x).to_i.to_s}.join
      end
      pcolours = colour_pixels.map do |x|
        nhexcode = nearest(x, lookup)
        ncolour = name_lookup[nhexcode]
        [x.upcase, nhexcode, *ncolour]
      end
      pixels.each_with_index do |x, i|
        x.red, x.green, x.blue = pcolours[i].last.map {|v| v ** 2}
      end
      iod.store_pixels(0, y, cols, 1, pixels)
      puts '... ' + y.to_s
    end
    iod.write 'pixels.jpg'
  end

  def hex_decimal(s)
    s.scan(/../).map{|x| ("%2d" %  "0x#{x}").to_i}
  end

  def nearest(original_colour, possible_colours=[])
    cr, cg, cb = hex_decimal(original_colour)
    k = possible_colours.map do |hexcode, rgb|
      r, g, b = rgb
      [hexcode, (cr - r).abs + (cg - g).abs + (cb - b).abs]
    end
    h = Hash[*k.flatten]
    h.min {|a,b| a[1] <=> b[1]}[0]
  end
end

if __FILE__ == $0
  wi = WI.new
  wi.colour('sample.jpg')
end

 接着，来看下效果。

 

 处理前：

 

 

处理后：