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comp.lang.ruby

load image bitmap into array

Snaggy

12/12/2008 7:35:00 PM

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..

thanks
Luca
2 Answers

Tim Hunter

12/12/2008 7:41:00 PM

0

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...
--with-quantum-depth info here:
http://www.imagemagick.org/script/advanced-unix-installation...
--
Posted via http://www.ruby-....

Snaggy

12/12/2008 7:54:00 PM

0

16 bit is fine as well.
I'll try it out as soon as I can
thanks