Script for drawing on http://editfight.com/

click.m

// Compile with:
// gcc -o click click.m -framework ApplicationServices -framework Foundation
//
// Usage:
// ./click -x pixels -y pixels
// At the given coordinates it will click and release.
//
// From http://hints.macworld.com/article.php?story=2008051406323031
#import <Foundation/Foundation.h>
#import <ApplicationServices/ApplicationServices.h>

int main(int argc, char *argv[]) {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSUserDefaults *args = [NSUserDefaults standardUserDefaults];

    int x = [args integerForKey:@"x"];
    int y = [args integerForKey:@"y"];

    CGPoint pt;
    pt.x = x;
    pt.y = y;

    CGPostMouseEvent( pt, 1, 1, 1 );
    CGPostMouseEvent( pt, 1, 1, 0 );

    [pool release];
    return 0;
}

draw.rb

# I tested this on OSX.
# You need to install dependencies first:
#
# brew install imagemagick@6
# PKG_CONFIG_PATH=/usr/local/opt/imagemagick@6/lib/pkgconfig gem install rmagick
# gem install color_diff

# You also need to download color palette from
# curl -o full.png https://i.imgur.com/H9Qpc4J.png
#
# Now setup the browser so top left pixel is at [52, 173]
# and the height of browser is as such whole board is 500x500 pixels.
#
# Usage: ruby draw.rb
#
# If you find this fun, please follow me on twitter :)
# https://twitter.com/sheerun
# 
require 'rubygems'
require 'rmagick'
require 'color_diff'

def rgb(r, g, b)
  { r: r.to_f / 255, g: g.to_f / 255, b: b.to_f / 255 }
end

$colors = [
  rgb(0, 0, 0),
  rgb(87, 87, 87),
  rgb(173, 35, 35),
  rgb(42, 75, 215),
  rgb(29, 105, 20),
  rgb(129, 74, 25),
  rgb(129, 38, 192),
  rgb(160, 160, 160),
  rgb(129, 197, 122),
  rgb(157, 175, 255),
  rgb(41, 208, 208),
  rgb(255, 146, 51),
  rgb(255, 238, 51),
  rgb(233, 222, 187),
  rgb(255, 205, 243),
  rgb(255, 255, 255)
]

def click(x, y)
  system("click -x #{x} -y #{y}")
end

def color(index)
  click(73+40*index, 146)
end

def color_distance(c1, c2)
  ColorDiff.between(
    ColorDiff::Color::RGB.new(c1[:r], c1[:g], c1[:b]),
    ColorDiff::Color::RGB.new(c2[:r], c2[:g], c2[:b]),
  )
end

def closest_color(color)
  _, index = $colors.each_with_index.min_by do |c, i|
    color_distance(color, c)
  end

  index
end

def pixel_at(img, x, y)
  width = img.columns
  height = img.rows
  color = img.pixel_color(x, y)
  rgb(color.red / 257, color.green / 257, color.blue / 257)
end

def color_at(img, x, y)
  width = img.columns
  height = img.rows
  color = img.pixel_color((width * x).round, (height * y).round)
  rgb(color.red / 257, color.green / 257, color.blue / 257)
end

def rectangle(startx, starty, width, height, col)
  i = 0
  x0 = 52
  y0 = 173
  color(col)
  click(x0, y0)
  (startx...startx+width).each do |x|
    (starty...starty+height).each do |y|
      click(x0 + 5*x, y0+5*y)
    end
  end
end


$palette = Magick::Image::read("full.png")[0]

def draw(startx, starty, width, height, img)
  i = 0
  x0 = 52
  y0 = 173
  if height == "auto"
    height = ((img.rows.to_f / img.columns) * width).round
  end
  if width == "auto"
    width = ((img.columns.to_f / img.rows) * height).round
  end
  img = img.remap($palette, Magick::NoDitherMethod)
  img = img.resize_to_fill(width, height)
  click(x0, y0)
  current_color = 0
  (0...width).each do |x|
    (0...height).each do |y|
      next_color = closest_color(pixel_at(img, x, y))
      if next_color != current_color
        color(next_color)
        current_color = next_color
      end
      click(x0+5*(startx+x), y0+5*(starty+y))
    end
  end
end

color(0); color(0)
img = Magick::Image::read("/Users/sheerun/Desktop/southpark.png")[0]
draw(0, 0, 20, "auto", img)

@sdegutis white is background

Oh right makes sense. So you just omit it then.