From: Tim Hunter <rmagick@...>
Date: 2008-12-13T04:41:25+09:00
Subject: Re: load image bitmap into array

Snaggy wrote:
> I'm trying to load a grayscale  image (some standard format will do,
> jpeg, png, bmp etc..) into an array, where I can access every pixel by
> its coohrdinates and where every pixel is described by a single number
> (0..255 8bit) from white to black.
> 
> How can I do that? I only need to read, not write images. It's for
> analysing them..
> 

You can do that with RMagick's Image#view.

However, the quantum range will depend on how ImageMagick is configured. 
If you require 0-255 then you'll need to make sure to install 
ImageMagick configured with --quantum-depth=8. Most of the pre-built 
ImageMagick packages that you get with Ubuntu or RedHat are built with 
--quantum-depth=16 so the quantum range is 0-65535.

Image#view doc here: 
http://studio.imagemagick.org/RMagick/doc/image3.html#view
--with-quantum-depth info here: 
http://www.imagemagick.org/script/advanced-unix-installation.php#linux
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