Watermark remover

gistfile1.rb

require 'rubygems'
require 'barracuda'
require 'RMagick'

include Magick
include Barracuda


prog = Program.new <<-'eof'

  void r2x(int r, int g, int b, double *x, double *y, double *z) {        
    *x = ((  66 * r + 129 * g +  25 * b + 128) >> 8) +  16;
    *y = (( -38 * r -  74 * g + 112 * b + 128) >> 8) + 128;
    *z = (( 112 * r -  94 * g -  18 * b + 128) >> 8) + 128;
  }
 
  float diff(int red1, int blue1, int green1, int red2, int blue2, int green2) {
    double l1; double a1; double b1; 
    double x; double y; double z;
    r2x(red1, green1, blue1, &l1, &a1, &b1);
    r2x(red2, green2, blue2, &x, &y, &z);
    
    double x1 = (l1 - x) * (l1 - x);
    double y1 = (a1 - y) * (a1 - y);
    double z1 = (b1 - z) * (b1 - z);
    
    return sqrt((float)(x1 + y1 + z1));
  }

  void mix_colors(int r1, int g1, int b1, int r2, int g2, int b2, int *r, int *g, int *b) {

    *r =  (int) (r1*0.5 + r2*0.5);
    *g =  (int) (g1*0.5 + g2*0.5);
    *b =  (int) (b1*0.5 + b2*0.5);
  }


  __kernel void clear(__global int *output_red, __global int *output_blue, __global int *output_green, __global int *img1_red, __global int *img1_blue, __global int *img1_green, __global int *img2_red, __global int *img2_blue, __global int *img2_green, __global int *img3_red, __global int *img3_blue, __global int *img3_green) {
    double x; double y;double z;
    int i = get_global_id(0);
    
    float diff1 = diff(img1_red[i], img1_blue[i], img1_green[i],img2_red[i], img2_blue[i], img2_green[i]);
    float diff2 = diff(img1_red[i], img1_blue[i], img1_green[i],img3_red[i], img3_blue[i], img3_green[i]);
    float diff3 = diff(img2_red[i], img2_blue[i], img2_green[i],img3_red[i], img3_blue[i], img3_green[i]);
    
    float maximum = max(max(diff1, diff2), diff3);
    
    int r; int g; int b;
    if (maximum == diff1) {
      mix_colors(img2_red[i], img2_green[i], img2_blue[i], img3_red[i], img3_green[i], img3_blue[i], &r, &g, &b);
    } else if (maximum == diff2) {
      mix_colors(img1_red[i], img1_green[i], img1_blue[i], img3_red[i], img3_green[i], img3_blue[i], &r, &g, &b);
    } else if (maximum == diff3) {
      mix_colors(img2_red[i], img2_green[i], img2_blue[i], img1_red[i], img1_green[i], img1_blue[i], &r, &g, &b);
    }
    
    output_red[i] = r;
    output_blue[i] = b;
    output_green[i] = g;
    
  }

eof

images = []

width = 0
height = 0

3.times do |t|
  images[t] = Image.read(ARGV[t])[0]
end

width = images.map{|i| i.columns}.max
height = images.map{|i| i.rows}.max

puts "Maximum height: #{height}, width: #{width}"

3.times do |t|
  images[t] = images[t].resize(width,height)
end

image_data_red = [[],[],[]] #Buffers to hold image data
image_data_green = [[],[],[]] #Buffers to hold image data
image_data_blue = [[],[],[]] #Buffers to hold image data

width.times do |x|
  height.times do |y|
    3.times do |t|
      pixel = images[t].pixel_color(x,y)
      image_data_red[t].push((pixel.red).to_i)
      image_data_green[t].push((pixel.green).to_i)
      image_data_blue[t].push((pixel.blue).to_i)
    end
  end
end

result_red = Buffer.new(width * height)
result_blue = Buffer.new(width * height)
result_green = Buffer.new(width * height)

prog.clear(result_red, result_blue, result_green,
            (image_data_red[0]), (image_data_blue[0]), (image_data_green[0]), 
            (image_data_red[1]), (image_data_blue[1]), (image_data_green[1]),
            (image_data_red[2]), (image_data_blue[2]), (image_data_green[2])
          )

z = 0
res_image =  Image.new(width, height)
width.times do |x|
  height.times do |y|
    res_image.pixel_color x,y, Magick::Pixel.new(result_red[z] , result_green[z] , result_blue[z] )
    z = z + 1
  end
end

res_image.write('output.png')