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mbr

LCD graphics problem

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I have a problem on Symbian S60, Nokia N82 with LCD screen refresh rate (also checked on 5500, and almost same situation occurs). In my app I'm moving a bitmap from left to right with speed 30fps (one frame 33 ms, but I also tried slower). To visualize my problem I created small bitmaps similar to that I'm using in my app: http://mbr-team.net/nokia/image_err/img.gif On this image I'm moving small bitmap with background color TRgb( 128, 64, 0 ); and line color TRgb( 128, 0, 0 ); 3 times by 1 pixel in left direction. To move bitmap I'm using double buffering with offscreen bitmap and Direct Screen Access API and the same problem is when using anti tearing API (Direct Screen Bitmap). On first column I created bitmaps that reflects what I'm seeing on phone screen and on the second column how this should look like. FRAME 1 is a steady state FRAME 2 is bitmap moved left by 1 pixel FRAME 3 is bitmap moved left by 1 pixel FRAME 4 is bitmap moved left by 1 pixel FRAME 5,6,7 is a steady state On screen we can see some kind of trail/smudge/streak or trace left by previous frame. I think differences between screen and memory is caused by low refresh rate of LCD. Using other colors for background and lines reduces this effect, but not solve problem. Is there any algorithm or method to avoid this situation? [Edited by - mbr on November 24, 2008 10:16:58 AM]

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Many low-power LCDs have very slow pixel response (particularly darkening). I have not tried this method, but you might consider adding a post-process step that overcompensates darkening pixels (look at differences with the previous frame(s?) and adjust the pixel values), but this will be expensive, and have to be tuned per-device.

Good luck.

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