0 Replies Latest reply on Apr 26, 2013 10:04 AM by skyscanner

    Disabling Unwanted Dither

    skyscanner

      Hi,

       

      I'm new here, so apologies if this is not the best forum to be posting on.

       

      I work for a company which makes digital displays, and I'm currently doing

      some work on the accuracy of colour rendering.

       

      Our display accepts DVI and DisplayPort, and while it can both dither and

      gamma-correct images, I currently have both features turned off, so that

      what appears on the display should exactly match what comes in from the

      graphics card. Our display is natively RGB at 8 bits per colour.

       

      I have a test image containing a green square, with a uniform pixel value

      of (0, 127, 0). When I feed it to our display, I get a dithered image in which

      some pixels are at level 127 and some at 128. As mentioned above, our own

      dither/gamma unit is turned off, but to completely eliminate any malfunction

      in that, we have sampled the video as it comes in to the system (before it

      even enters our gamma/dither unit) and the dither is definitely present.

       

      On moving our display around from one PC to another, we have found that

      even with identical graphics cards, the unwanted dither does not always

      appear - we found it on two of our three HD 3600 PCs. On the third PC, there

      was no dither, and the image was exactly as it should be. The common spec

      of all three PCs is below.

       

      The unwanted dither has been reproduced on both DVI and DisplayPort outputs.

       

      I couldn't see any dither control in Catalyst, but maybe it goes by another

      name.

       

      Any tips on how to ensure that the graphics card outputs colours verbatim

      and undithered?

       

       

       

       

      PC Spec

      =======

       

      Driver Packaging Version            8.97.100.3-120703a-142837C-ATI

      Catalyst™ Version         12.6

      Provider AMD.   

      2D Driver Version           6.14.10.7267

      2D Driver File Path         System/CurrentControlSet/Control/Video/{2D1F3F58-5AE9-46F3-B88A-9A1471B4A3B8}/0000

      Direct3D Version            6.14.10.0911

      OpenGL Version            6.14.10.11653

      Catalyst™ Control Center Version           2012.0703.2356.41139

       

      Primary Adapter

      Graphics Card Manufacturer        Powered by AMD

      Graphics Chipset           ATI Radeon HD 3600 Series

      Device ID           9598

      Vendor  1002

       

      Subsystem ID    2242

      Subsystem Vendor ID    1028

       

      Graphics Bus Capability PCI Express 2.0

       

      Maximum Bus Setting    PCI Express 2.0 x16

       

      BIOS Version    010.088.000.027

      BIOS Part Number         113-B38201-104

      BIOS Date         2008/08/05

       

      Memory Size     256 MB

      Memory Type    DDR2

       

      Core Clock in MHz         725 MHz

      Memory Clock in MHz    500 MHz