From: Rob Biedenharn <Rob@...>
Date: 2009-12-08T03:35:26+09:00
Subject: Re: Reading Images

On Dec 7, 2009, at 1:03 PM, Fleck Jean-Julien wrote:
> 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

Oh, new to me! I'm going to have to remember that one. I have to admit  
that I use Ruby system() calls to run various 'convert' operations  
rather than go the RMagick route, too. Needing all the pixel data  
might make it worth using RMagick, but you certainly can't get much  
simpler that your image-as-text solution.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com