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"Colour bars" flashing in vision when watching projected TV show? |
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#1 |
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Forum Member
Join Date: Dec 2001
Location: West London
Posts: 24,303
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"Colour bars" flashing in vision when watching projected TV show?
Went to a screening of a TV show where the picture was projected on to a screen, about the size of a medium cinema screen (so not huge but not small). Picture was very sharp but if I blinked or looked quickly from left to right (or vice versa) I saw flashes of colour, a bit like colour bars, momentarily across the screen. What causes this, and why doesn't it happen with digital TV or cinemas?
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#2 |
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Join Date: Aug 2003
Location: Heart of England.
Posts: 8,632
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Possibly "rainbow effect" caused by the use of a spinning colour wheel in some DLP projectors. Not everybody is affected by it though.
Doesn't happen with other types of projectors, such as LCD or a triple chip DLP. You can google "rainbow effect" or "RBE" for a full explanation. |
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#3 |
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Forum Member
Join Date: Dec 2001
Location: West London
Posts: 24,303
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Quote:
Possibly "rainbow effect" caused by the use of a spinning colour wheel in some DLP projectors. Not everybody is affected by it though.
Doesn't happen with other types of projectors, such as LCD or a triple chip DLP. You can google "rainbow effect" or "RBE" for a full explanation. |
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#4 |
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Join Date: Jun 2003
Location: Cheshire
Posts: 6,450
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Not everyone affected because they:
1) are less sensitive to (or just don't notice) colour as much as others 2) see it but ignore the effect 3) focus on the central part of the image so they don't scan their eyes across the picture to provoke RBE 4) are more tolerant of lower frequency refresh rate. They don't see florescent lights flickering and never noticed 50Hz CRT picture refresh flickering |
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#5 |
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Join Date: Apr 2006
Location: North Derbyshire
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Quote:
never noticed 50Hz CRT picture refresh flickering
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#6 |
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Join Date: Jun 2003
Location: Cheshire
Posts: 6,450
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CRT flicker: Well, not until the mags pointed out how they could provoke the effect using peripheral vision.
It's much the same now with DLP RBE. Faster spin speeds mean it's no longer a major issue for a lot of people when viewing normally using a home cinema single chipper. However, it can be provoked. |
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#7 |
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Forum Member
Join Date: Dec 2001
Location: West London
Posts: 24,303
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Quote:
CRT flicker: Well, not until the mags pointed out how they could provoke the effect using peripheral vision.
It's much the same now with DLP RBE. Faster spin speeds mean it's no longer a major issue for a lot of people when viewing normally using a home cinema single chipper. However, it can be provoked. |
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