Image manipulating with lua5.1 -imlib2 on ubuntu 14.04

Hi,

Gmic is a bit complicated, gluas has to many bugs and imagemagick is in C, but you can`t write C programs and need to write your own simple image filter?
Then the following instruction might be intertesting if you have ubuntu installed:

Lua is implemented in pure ANSI C and compiles unmodified in all platforms that have an ANSI C compiler. Lua also compiles cleanly as C++. source:
http://www.lua.org

How to install lua5.1 and the imlib2 plugin :

Code:

sudo apt-get remove  lua5.2
sudo apt-get install  lua5.1  luarocks libimlib2-dev
sudo luarocks install lua-imlib2

Reference for easier writing your own image filter you `ll find here:

http://asbradbury.org/projects/lua-imlib2/doc/

However i didn`t understand somje things of it at the beginning so im now posting a sample script:

Code:

-- simple selective blur
-- by bluedxca93

require("imlib2")


local im =  imlib2.image.load("input.png")
local xlength = im:get_width()
local xheight = im:get_height()

for x=0, xlength-1 do
  for y=0, xheight-1 do
     level = 15
     c0 = im:get_pixel(x, y)
     c1 = im:get_pixel(x-1, y-1)
     c2 = im:get_pixel(x, y-1)
     c3 = im:get_pixel(x+1, y-1)
     c4 = im:get_pixel(x-1, y)
     c5 = im:get_pixel(x+1, y)
     c6 = im:get_pixel(x-1, y+1)
     c7 = im:get_pixel(x-1, y+1)
     c8 = im:get_pixel(x-1, y+1)

      c0r = (c0.red)  
      c1r = (c1.red)
      c2r = (c2.red)
      c3r = (c3.red)
      c4r = (c4.red)
      c5r = (c5.red)
      c6r = (c6.red)
      c7r = (c7.red)
      c8r = (c8.red)
         
      c0g = (c0.green)
      c1g = (c1.green)
      c2g = (c2.green)
      c3g = (c3.green)
      c4g = (c4.green)
      c5g = (c5.green)
      c6g = (c6.green)
      c7g = (c7.green)
      c8g = (c8.green)
 
      c0b = (c0.blue)
      c1b = (c1.blue)
      c2b = (c2.blue)
      c3b = (c3.blue)
      c4b = (c4.blue)
      c5b = (c5.blue)
      c6b = (c6.blue)
      c7b = (c7.blue)
      c8b = (c8.blue)
       
          if c0r > c1r then cv1r = c0r - c1r else cv1r = c1r - c0r end
          if c0r > c2r then cv2r = c0r - c2r else cv2r = c2r - c0r end
          if c0r > c3r then cv3r = c0r - c3r else cv3r = c3r - c0r end
          if c0r > c4r then cv4r = c0r - c4r else cv4r = c4r - c0r end
          if c0r > c5r then cv5r = c0r - c5r else cv5r = c5r - c0r end
          if c0r > c6r then cv6r = c0r - c6r else cv6r = c6r - c0r end
          if c0r > c7r then cv7r = c0r - c7r else cv7r = c7r - c0r end
          if c0r > c8r then cv8r = c0r - c8r else cv8r = c8r - c0r end

          if c0g > c1g then cv1g = c0g - c1g else cv1g = c1g - c0g end
          if c0g > c2g then cv2g = c0g - c2g else cv2g = c2g - c0g end
          if c0g > c3g then cv3g = c0g - c3g else cv3g = c3g - c0g end
          if c0g > c4g then cv4g = c0g - c4g else cv4g = c4g - c0g end
          if c0g > c5g then cv5g = c0g - c5g else cv5g = c5g - c0g end
          if c0g > c6g then cv6g = c0g - c6g else cv6g = c6g - c0g end
          if c0g > c7g then cv7g = c0g - c7g else cv7g = c7g - c0g end
          if c0g > c8g then cv8g = c0g - c8g else cv8g = c8g - c0g end

          if c0b > c1b then cv1b = c0b - c1b else cv1b = c1b - c0b end
          if c0b > c2b then cv2b = c0b - c2b else cv2b = c2b - c0b end
          if c0b > c3b then cv3b = c0b - c3b else cv3b = c3b - c0b end
          if c0b > c4b then cv4b = c0b - c4b else cv4b = c4b - c0b end
          if c0b > c5b then cv5b = c0b - c5b else cv5b = c5b - c0b end
          if c0b > c6b then cv6b = c0b - c6b else cv6b = c6b - c0b end
          if c0b > c7b then cv7b = c0b - c7b else cv7b = c7b - c0b end
          if c0b > c8b then cv8b = c0b - c8b else cv8b = c8b - c0b end

            if level > cv1r and level > cv2r and level > cv3r and level > cv4r and level > cv5r and level > cv6r and level > cv7r and level > cv8r  then   dr = ((c1r + c2r + c3r + c4r + c5r + c6r + c7r + c8r )/8 ) else dr = c0r end

            if level > cv1g and level > cv2g and level > cv3g and level > cv4g and level > cv5g and level > cv6g and level > cv7g and level > cv8g  then   dg = ((c1g + c2g + c3g + c4g + c5g + c6g + c7g + c8g )/8 ) else dg = c0g end

            if level > cv1b and level > cv2b and level > cv3b and level > cv4b and level > cv5b and level > cv6b and level > cv7b and level > cv8b  then   db = ((c1b + c2b + c3b + c4b + c5b + c6b + c7b + c8b )/8 ) else db = c0b end

              cf = imlib2.color.new( dr, dg, db)
     
  im:draw_pixel(x, y, cf)
  end
end


im:save("output.png")

file name: blxblur.lua
Usage lua blxblur.lua reads input.png and prints output.png

Writing filters is easy, but the required text, to do it is very long, but with some simple find and replace command and a logical way to write them, you don`t type that much. believe me. I thought the code is long, but it schould help people to learn how to write their first image processing filters and thats why i posted it in full length!.
It is human readbale code you do use for source coede and the lua interpreter will help you to find errors more quickly than any other meothod ive tried so far. Its ten times faster than using bash for doing it but also five times slower than a imagemagick function, however quickly enough to convert images in a reasonable amount of time.

regards bluedxca93