Re: [Libjpeg-devel-6x] request to join libjpeg

[Bob F. <bfr...@si...>]

On Sat, 5 May 2012, Johnathan wrote:

> I would like to join the libjpeg discussion list to recommend adding a color conversion which is missing
> from the current implementation.

This is the discussion list for libjpeg 6x which is stable and no 
longer really developed.

> We are seeing increasing use of 32 bit RGBA images on the internet, and JPEG is the *only* popular file
> format which does not support RGBA, even though the specification easily allows this.
> 
> Why is this? There is really no reason why JPEG should not support RGBA, because it already has a compatible
> format, namely YCCK.

JPEG does not work well for alpha channels because it is lossy.  This 
produces poor visual results for normal usages.

There is a JPEG-based format known as JNG which uses JPEG for the RGB 
parts and lossless PNG type coding for the alpha part.  The file 
format is structured like PNG.

> With this simple addition, JPEG will finally support full 32 bit RGBA images, making it more useful in
> applications requiring transparency such as web browsers, games, mobile apps, and so on.

Consider using and promoting JNG.

Bob
-- 
Bob Friesenhahn
bfr...@si..., http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/