Graphics

There are too many graphics formats! The comp.graphics.misc FAQs give some pointers. Important formats and libraries include:

GIF

This is the most common image file format on the internet. At the beginning of 1995, Compuserve/Unisys asserted patent rights on the LZW compression algorithm in the GIF format. For the full story see, for example, the comp.graphics.misc FAQ, part 1. If, after 1 January 1995, you create or modify commercial software which supports either GIF or TIFF-LZW, then you need a licence from Unisys. You do not need a licence for non-commercial or not-for-profit software.

See also the Burn All GIFs webpages.

PNG (master)

Portable Network Graphics. Format designed after the Compuserve/Unisys biz. The GIF format was reportedly showing its age anyway. There is growing, but not yet ubiquitous, browser support for the format. There's a libpng test suite

pbmplus

This defines a collection of formats, PBM, PGM and PPM (for bitmaps, greymaps and full-colour images respectively), plus PNM which does assorted manipulations on the internal formats. The library, available in `all the usual places', is concerned with reading and writing files in these formats and is not, as far as I can see, a collection of libraries for other formats. It therefore comes with a collection of applications which convert between P?M files and other formats, so that you can convert between any two formats by going into and out of P?M.

NetPBM

This is a collection of converters from one image format to another. It's based on the `pbmplus' library, with extensions. This distribution seems to have largely replaced by incorporation the pbmplus distribution.

JPEG

Image format designed for photographic images (ie, not bitmaps). The Independent JPEG Group distributes a well-known JPEG library.

Postscript

Not really a `graphics format'. Tutorial, tutorial and reference (ps), comp.lang.postscript FAQ

There's a collection of graphics file format links at <http://www.dcs.ed.ac.uk/~mxr/gfx/>.

Norman 1 January 2001