From: Fleck Jean-Julien <jeanjulien.fleck@...>
Date: 2009-12-08T03:03:53+09:00
Subject: Re: Reading Images

Hello,

> The problem is not with ruby, but with the complexity of the .jpeg format.
> RMagick has done all the hard work, but it depends on installing
> ImageMagick. I use RMagick regularly, and installing ImageMagick took a
> couple of false starts (I use both OSX and Ubuntu), but in the end I got all
> the dependencies right. Then, RMagick "just works." So, install ImageMagick
> and RMagick and impress your mates.


Well, rather than using RMagick which seem a bit complex at first
sight, you can always call 'convert' (from ImageMagick) with a system
call and transform your jpg in a text file:

jpg = "image.jpg"
txt = "image.txt"
system "convert #{jpg} #{txt}"

The image.txt file looks like

# ImageMagick pixel enumeration: 712,490,255,RGB
0,0: (226,188,115)  #E2BC73  rgb(226,188,115)
1,0: (227,189,116)  #E3BD74  rgb(227,189,116)
2,0: (226,188,115)  #E2BC73  rgb(226,188,115)
...
709,489: (224,207,125)  #E0CF7D  rgb(224,207,125)
710,489: (211,203,120)  #D3CB78  rgb(211,203,120)
711,489: (134,129, 45)  #86812D  rgb(134,129,45)

and its really easy to get the size (712x490) and the pixels colors
reading the file directly throught

File.open(txt) do |f|
  f.readlines.each do |line|
    # action on each line using regexp to get the colors
  end
end

Cheers,

-- 
JJ Fleck
PCSI1 Lycée Kléber