brinkley@synapse.stanford.edu (Jim Brinkley) (12/14/90)
We are getting ready to buy one or more color NeXTs. The main use will be to display 12 bit grayscale computed tomography images. I already have a program to do that on the B/W NeXTs. The way I do it is to use software to map the original bits to the 8 bit postscript format, then let the display postscript trasnfer functions map the 8 bits to the 2 bit screen. The problem is that software mapping of 12 bits to 8 bits takes a long time. What I'd like is a 10-12 bit hardware color map that I could quickly fill with greylevels - that way the mapping would be very fast (the user often needs to change the mapping interactively when looking at CT images). My question is (and I know this was asked before, but no one seemed to know the answer then): is there a hardware color map on either the NeXTStation Color, or on the NeXTDimension board? Looking at the specs for the NeXTStation color system it looks like it allows 16 bits/pixel, of which 12 bits are pixel value, and that is then mapped to a possible 4096 bits. So that looks like a hardware color map. On the other hand, the NeXTDimension shows 24 bits of pixel value, but it probably only displays in RGB mode, so you can only display 8 bits of greyscale/pixel. I don't see any mention of a color map in the NeXTDimension, so it looks like I'd still have to do the mapping from 12 bits to 8 bits in software on the NexTDimension. On the surface it therefore looks like the NeXTStation Color system is the one to use for grayscale imaging when the images are greater than 8 bits/pixel, assuming the NeXTStation Color really has a hardware color map. Does anyone know what's correct here? I'd really like to try the NeXTDimension for the video compression and graphics, but maybe I'll be forced to use the NeXTStation Color since my main application is imaging. Thanks for any reponses. I'll post a summary to the net if people are sufficiently interested. Jim Brinkley