Originally Posted by howsweet
So I have to assume one can still get a good digital camera that can photograph purple, but from what I've read on camera forums, you can definitely pay a whole lot for a high end camera and still not get purple
Electronic imaging sensors have been having trouble with subtle shades of blue and purple for a very long time. Even on professional equipment.
My best friend is a videographer, who specializes in figure skating competitions. Over 20 years ago, I was working a video crew with him, at a skating competition in Palm Desert. He was using what is still, hands-down, the best standard definition video camera for "difficult" lighting situations ever made: an Ikegami HL-55 (he's only now retiring his HL-55s, as he transitions to HDTV). That camera sold, new, for $35,000. Not including the lens. Back in 1989 dollars. He bought his, used for $20,000 each. An irate mother came to us, as we were shutting down for the night: her daughter's two-tone blue-and-purple dress (which she'd designed and made) came out all royal blue, and she was livid (talk about misplaced priorities!). I went back to the U-Matic master tape, and I found that if I adjusted the color phase on the timebase corrector to the point where the kid almost looked jaundiced, you could see enough difference between the blue and the purple to tell that the dress was two-tone. So the mom was happy with a tape that sacrificed a healthy skintone (and was dubbed from the master, instead of recorded live), so long as that damn dress was visibly two-tone.
So don't be surprised at cakes that look purple to the human eye, and maybe even to film, yet look blue on video or digital. The technology of solid-state imaging sensors has come a long way, but both film and vacuum tube imaging sensors have had a big head-start.