From: Tim Hunter <sastph@...>
Date: 2005-04-05T03:09:43+09:00
Subject: Re: Extension question

Joe Van Dyk wrote:
> Hi,
> 
> I'm generating a fairly large image file (can be 10000x10000) pixels
> by reading some binary data and setting each pixel.  As you can
> imagine, pure Ruby is REALLY slow, I think because of the loops.  I've
> written the program in C and it's literally hundreds to thousands of
> times faster (depending on image size).

Have you tried RMagick? http://rmagick.rubyforge.org.

The constitute method may be useful: 
http://www.simplesystems.org/RMagick/doc/image1.html#constitute

That method requires you to have all the pixel data in memory at once, 
though, which could be a problem unless you have a LOT of RAM.

You could use import_pixels to set just a subset of pixels at a time:
http://www.simplesystems.org/RMagick/doc/image2.html#import_pixels

That would minimize the memory requirements.

In both cases you'd have to convert your binary data to a Ruby numeric 
type. Don't know whether that would be too slow or not.