Re: [Algorithms] Image compression

[Richard F. <ra...@gm...>]

nice links, thanks. Makes me think that approaching the compression of
images by blocks is a coders dream but not good for quality. I'm rethinking
the approach for non power of two images and trying to do it without using
blocks at all.

2009/8/7 metanet software <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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-- 
fabs();
Just because the world is full of people that think just like you, doesn't
mean the other ones can't be right.