On Sun, 23 Mar 2008 00:02:11 -0700 "Vitaliy" wrote: > However, we are in the process of creating a wizard-style > troubleshooter and I have a question: would a color blind person be > able to see a "flickering" LED, one that rapidly changed its state from > R to Y? I assume the answer is "yes", since the brightness would > change, and even a b/w camera should be able to "see" it, but I just > want to get a confirmation from someone who knows for sure. Color blindness can take several forms (see http://en.wikipedia.org/wiki/Color_blindness - very well-done article). Red/green color blindness is just one of the forms. I had a friend who was extremely 'Daltonic' - he perceived very small variations of green as what we see over our entire spectrum - but had to ask his son to read resistor codes. I suspect that category of afflicted people would detect small variations by mixing red (getting yellow) as huge changes. But that wouldn't do for normal observers. I would suggest you use on/off patterns to indicate errors. John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist