Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
HELP! Has anyone, but myself, experienced a severe problem with the IDL color_quan function? I am using IDL v2.2 and v2.2.1 on an Ultrix/MIPS DEC5000 workstation. The color_quan function repeatedly causes the entire IDL session to crash, with either a Segmentation Fault or Process Killed on Unaligned Access message from the operating system. To say the least, this is a very inelegant way to leave IDL, as all one's variables are lost! A typical call to color_quan might look like this: (1) out=color_quan(ri,gi,bi,rct,gct,bct) with ri,gi,bi being bytewith ri,gi,bi and out being byte images and rct,gct,bct being the returned color tables then to be followed by: (2) tvlct,rct,gct,bct & tv,out But more often than not, I never get past step 1. I can hear the disk go whirring off, maybe paging, then stop. This is my clue it'll never come back. Eventually, 20 to 30 seconds later it dumps me all the way back to Ultrix. There are two really goofy clues I can't make sense of: 1) It is data IDEPENDENT. Calling color_quan from the command line with a certain set of images will kill IDL, but calling it EXACTLY the same way with the SAME images from deep within a multi-thousand line procedure always works. I tried making a dummy procedure to see how "deep" the call had to be nested, to no avail, and eventually gave up on this poking around in the dark. 2) It is data DEPENDENT. Certain images can be color_quanned from the command line, while others can't. It seems to have nothing to do with image size or data distributions. This is a REAL problem for us. We bought IDL specifically to do image processing on an 8-bit display. Previous experience with color_quan in IDL v.2.1.1 convinced us that it was an excellent way to view 24-bit images on an 8-bit display. But the new versions (v2.2 and later) repeatedly fail, as described above. Has anyone else experienced these problems? Any clues? Is anyone regularly using color_quan from the command line and NOT having problems? I'd especially like to hear from other DEC/Ultrix users. There's a six-pack of homebrew in this for whoever comes up with an answer. :) Meanwhile, I think I'll go have one, or two! - JOSEPH WILLIS BOARDMAN "Leave dead dogs alone" Email: joe@syd.deg.csiro.au Phone: 61-2-887-8884