Re: [Algorithms] Image compression

[metanet s. <met...@ya...>]

Some of CBloom's blog notes might be of interest to you, here are some recent ones that are relevant:

http://cbloomrants.blogspot.com/2009/02/02-19-09-png-sucks.html
http://cbloomrants.blogspot.com/2009/05/05-13-09-image-compression-rambling.html
http://cbloomrants.blogspot.com/2009/05/05-14-09-image-compression-rambling.html
http://cbloomrants.blogspot.com/2009/07/07-06-09-small-image-compression-notes.html
http://cbloomrants.blogspot.com/2009/07/07-07-09-small-image-compression-notes.html




--- On Fri, 8/7/09, Richard Fabian <ra...@gm...> wrote:

> From: Richard Fabian <ra...@gm...>
> Subject: [Algorithms] Image compression
> To: "Game Development Algorithms" <gda...@li...>
> Received: Friday, August 7, 2009, 6:41 AM
> Not sure if i'm reinventing the wheel
> here, but I've been working on
> an in house image compressor for our DS games, and had an
> idea that i
> thought was a novel approach to solving the lossy
> compression problem.
> 
> I started with DCTs (which were terribly slow on the DS, so
> were soon
> discouraging), then tried wavelets, which did provide a
> great speed
> increase, and good image quality, but after working with
> them for a
> while i had the idea that maybe what we need to encode is
> the terrain
> of the image. not the two distinct 1D signals.
> 
> So, with the idea of "doing it in 2D" in mind, i tried to
> develop an
> algorithm that instead of taking the differences between
> pixels, it
> assumes that the pixels are part of a larger image and
> starts from an
> assumption that anything other than the predicted value of
> a pixel is
> notable. I took the vertical gradient, horizontal gradient,
> and the
> _saddle_ (diagonal difference / Determinant), and these
> were then the
> values recorded for later use in the compression. This 2D
> approach
> made a small but significant difference in the
> compressability of the
> image over wavelets, but I'm not brilliant at compression,
> just not
> incompetent, so I requested the right to start a
> source-forge project
> based on the library so that all the other games developers
> could both
> benefit and help me make this fast and quite good
> compressor into
> something really cool for us all to use.
> 
> https://sourceforge.net/projects/mergelet/
> 
> Sorry that my code is a bit wandery in places, and I don't
> use
> comments much, I tend to comment with variable names and
> structure of
> code instead.
> 
> Also, I'm new to source-forge, so don't know how everything
> works yet.
> 
> -- 
> fabs();
> Just because the world is full of people that think just
> like you,
> doesn't mean the other ones can't be right.
> 
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