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Mr SQL
Registered: Feb 2023
Posts: 137 |
LCD burned by interlace algorithm
I've been working on a game that burned an image into my LCD screen after playing it for 1/2 hour in CCS64 using 640x480 full screen mode.
The game uses an interlacing algorithm to create more colors at 30 FPS by combining two 60 Hz frames. I've used this effect before but not with all 16 colors at once.
I was able to get rid of the burn by leaving the monitor off for a few hours and then leaving a white background display on but have never seen this happen before.
I could not repeat the experiment using VICE, though it also displays the game very well. Possibly the occasional dropped frame to synch to the real C64 NTSC Hz rate of 59.x may act as a screen saver saving the LCD display from the algorithm.
Anyone have an idea what happened? |
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Flotsam
Registered: Jan 2004
Posts: 84 |
Palette you have in CCS64 perhaps has bigger contrast? |
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mankeli
Registered: Oct 2010
Posts: 146 |
If you are rapidly flickering two images on an LCD screen, the physical liquid crystals and the display driver's opinion about their orientation might get "desynched".
(I think! - the crystals have some mass, so the driver has to estimate how much it needs to drive them to reach the desired orientation, basically same thing as with e-ink displays but faster)
I've had this with some Shadertoy experiments and it has gone away in an hour or so. |
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Clarence
Registered: Mar 2004
Posts: 121 |
Jay of Graffity had the same effect on an Eizo monitor. Sidwizard's idle rastertime jiggle was left on for a couple of hours on full screen (hdmi from real c64). Then he switched over to pc on display port, the burn in of the small rastertime jiggle area was still visible dimly vibrating. It's called 'dynamic burn in' he found out. It cured itself by turning off the monitor until the next day. |
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Mr SQL
Registered: Feb 2023
Posts: 137 |
Quoting ClarenceJay of Graffity had the same effect on an Eizo monitor. Sidwizard's idle rastertime jiggle was left on for a couple of hours on full screen (hdmi from real c64). Then he switched over to pc on display port, the burn in of the small rastertime jiggle area was still visible dimly vibrating. It's called 'dynamic burn in' he found out. It cured itself by turning off the monitor until the next day.
Yes it was exactly as you describe with dimly vibrating spectral colors. I thought I'd broken the monitor initially.
I tried reproducing it and got faint results after several minutes but I didn't run the program for as long as I did initially.
Quoting mankeliIf you are rapidly flickering two images on an LCD screen, the physical liquid crystals and the display driver's opinion about their orientation might get "desynched".
(I think! - the crystals have some mass, so the driver has to estimate how much it needs to drive them to reach the desired orientation, basically same thing as with e-ink displays but faster)
I've had this with some Shadertoy experiments and it has gone away in an hour or so.
Interesting technical description and theory! I wonder if the liquid crystals behave like memory foam or memory metal returning to their initial state over time.
Quoting FlotsamPalette you have in CCS64 perhaps has bigger contrast?
Palette probably is a factor. With only a few colors this effect does not happen, I only noticed it after the program was using many colors. I think the red green and blue liquid crystal may be on separate sheets overlaid each with their own transistor array. |
