Ulrich Seydel inquired about software to merge 8bit grayscale images to 24bit color and subsequently to 8bit color. On the Mac/PC side- Adobe Photoshop will do this quite well. Just paste the individual images into either the R,G, or B channels and then convert to indexed (256) color. Photoshop also is available for SGI. On the unix side- the San Diego Supercomputer Center's imtools suite will also do this. However, the component imtools are all command-line and slight adjustments in registering images is more difficult than in Adobe Photoshop. However, batch processing in unix is easier although there are now Photoshop aids that enable batch processing of Photoshop functions. imtools is public domain and ftp'able from ftp.sdsc.edu in the /pub/sdsc/graphics/imtools directory. Source code and binaries for most workstations (SGI, Sun, HP, Dec, even Cray) are available. daniel chin agouron institute [log in to unmask] http://agi.org/otherD/Dan.html