Originally Posted by tranzixter
RBE is the result of the eye not integrating light projected to a single pixel on the screen......
over one 8 nanosec long time window, a single pixel on the screen is illuminated by light reflected off a single the DLP pixel mirror, through the color wheel resulting in sequential sub-nanoseconds long splashes of colored light on the pixel target.....e.g. a splash of primary color1, splash primary color 2, splash primary color 3, splash primary color 4, splash primary color 5, splash primary color 6...... one after the other. Further during each of the color splashes, the DLP mirror is modulating rapidly on/off to adjust the intensity of the light (the more on the brighter). The intensity modulation is used of course for total light intensity but also to fine tune the color mix so for example primary color one is more intense then primary color 2 to make it more red. So the combination of primary colors projected sequentially one at a time on the screen, in conjuntion with a on/off intensity modulation of the mirror, all occurring over a microseconds time window, when viewed by the eye-brain appear as one constant color and intensity. We are just not pphysiologiclycapable of discerning individual events that occur at such rapid speed. The result is the eye-brain then blends together or integrates all the information of the color splashes and light intensity changes that occur over the tiny time window and then the pixel to our view, becomes the intended color and intensity. Now when considering this is happening 2 million times every 1/60 second is beyond comprehension!
Claims of eye fatigue and headaches are based on the theory that our eye-brain is strained trying to perform this massive integration over the entire screen and changing every 1/30 or 1/60 sec.
RBE is the result of the eye-brain failing to completely integrate all this time sequenced information on a single pixel. Usually it is the result of eye movement from turning your head rapidly. When that is done, you may not have completed the integration of all sequential color and intensity components....you may have moved your center of vision off the pixel and integrated say only 1/2 the information occurring in the 8 nanosecond pixel time window and resulting in colors that are not correct and stand in stark contrast to the majority of pixels which you were able to completely eye-brain integrate. Sometimes these artifacts remind of rainbows. WIth todays DLPs spinning at 14.4KRPM its very very difficult if not impossible to even force yourself to see RBE.
When people are susceptible to RBE on these new generation 7 sets, I've always wondered why. Do some folks have some form of awake rapid eye movement, causing incomplete pixel integration per the mechanism described above? Or do some have exceptionally fast eye brain nerves and synaptics that allows them to see the individual DLP color and light intensity splashes ?.
Hi. I'm the unofficial ophthalmologist for the AVS Forum, and I want to congratulate you on a fine description of the cause of "Rainbow Effect" (aka RBE).
The eye has two types of eye movements "Fast pursuit" and "Slow Tracking"
RBE is due to the "Fast Pursuit" kind of eye movements, the very fast eye movement we use to acquire an object in the center of vision, or when the eyes dart about the TV screen while watching the video. *Maybe* you've seen this while driving and noted LED brake lights have a "strobe" effect if you are darting your eyes past them rapidly, or noting the lights on a radio tower at night having a "strobe" effect if you gaze past them quickly (vs. their normal steady state if you stare at them without eye movement). Same eye movement and visual process as RBE. Those examples are monochromatic, but with the DLP, each "strobe" has a different color and slightly offset in space to the previous one... hence the "rainbow" effect.
People not susceptible to RBE may have a "slower" Fast Pursuit eye motion, or maybe are not likely to look around the screen much, or are, perhaps, just not "aware" of them, although the eye may be transmitting the signal to the occipital cortex visual center where they are subconsciously supressed.
Vision is more than just the eyes and the retina, there is A LOT of video signal processing (addition, subtraction, contrast enhancement, hue alteration, white balance processing, detail and motion processing) which takes place not only in the retinal neural net, but in the visual cortex of the brain.
Obviously, those persons susceptible to RBE have a far superior eyes AND brains...