As a random off topic, I understand the red/purple hue as the IR filter on your camera lens. Don't ever be conn'ed buying a digital camera that can see infra-red. Most all of them can. They actually put a filter over the lens to filter it out cause it makes photos look weird. The filter is most often purple/red. So when you point a digital camera at a fire or other heat source the photo tends to take a red/purple hue as the strong IR overloads the filter. If you want an IR digital camera, just use a solvent to remove the filter coating.