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Portrait vs. landscape display/resolution settings, aspect ratio

johannes larsch
Prodigy 40 points
Other Parts Discussed in Thread: DLP4500, DLPC350

Hi,


A very basic question: When I connect the dlp4500 to my windows 7 computer, it is recognized as a screen with a resolution of 912x1140, which amounts to a portrait format. For some reason however, Windows recognizes it as being in landscape orientation and therefore, projections coming via the hdmi input become heavily stretched.

Is this a driver issue or is there a setting I am missing?

Thanks in advance
Johannes

  • 0
    Prodigy 40 points
    I guess the reason for this display behavior is the diamond shaped pixels. I get that. I am curious what people think is the best way to compensate for this effect and achieve proper display of image content that was originally designed for square pixels.

    1) in video mode. What is the best way to automatically apply the appropriate scaling to the hdmi input? I.e. if I want to output a windows 7 screen content via hdmi, what is the best way to re-scale that input?

    2) in pattern mode with HDMI as input source, I figure I can squeeze the input width by a factor of 2 to compensate for the pixel geometry. Assume I want to display a perfect circle, I would first generate an image that is twice as wide as the native resolution (2x912 = 1824 width, 1140 height). I draw the circle on this image, then I squeeze that image to 912x1140. The projector's geometry un-squeezes the image to the correct aspect ratio. This seems to work but somehow seems cumbersome. Again, is there a better way to do it?

    Johannes
  • 0 in reply to johannes larsch
    TI__Mastermind 30875 points
    Hello Johannes,

    #1. For best display input the data in WXGA format 1280x800. Inside the DLPC350 controller there is square to diamond mapper hw block that will take care of displaying WXGA orthonal pixel frame into native 912x1140 diamond pixel arrangement.

    #2. For the pattern display mode, you must always be sending 912x1140 square pixel format ONLY. The scaler functionality or diamond mapper hw block are disabled in the Pattern mode. Although 912 looks smaller in size than 1140 but because of the diamond orientation of pixels it is the 912 horizontal line that displayed as bigger than 1140 height.
    If you are capturing the displayed images in this mode, the key is that the alternate rows are shifted by 1/2 pixel in horizontal direction
    <> <> <> <> --- row 1
    <> <> <> <> --- row 2
    <> <> <> <> --- row 3
    <> <> <> <> --- row 4

    Regards,
    Sanjeev