This article is from the comp.sys.acorn FAQ, by Paul Vigay with numerous contributions by others.
Four utilities exist to let you create these.
spr2gif will take a sprite and convert it to a gif file. It will interlace and render transparent the gif as well. For the transparency it uses the colour of the first masked pixel it encounters in the sprite - suitable for automated gif image creating. (No need to twiddle with specifying transparency colours.)
WebGIF allows you to add transparency and interlacing to your GIFs as well.
Creator, from about v2.00, can create interlaced GIFs. However you have to specify the transparency colour directly.
And finally InterGIF not only can create interlaced, transparent GIFs but is capable of creating animated ones as well.
On top of these utilities an increasing number of commercial programs can create Interlaced GIFs, Photodesk being a prime example.
When reading this section it must be remembered that all references to the Emulator software featured in this section are to the Risc PC PC Second Processor Card controlling software, and not to the older Software PC Emulator software released by Acorn.