Monitor's Pixels are not Square

Discussion in 'Amateur Video Production' started by Ken, Nov 25, 2004.

  1. Ken

    Ken Guest

    My monitor's pixels are "rectangular". And oddly, the ratio is the
    opposite of DV !!! With DV AVI's using the 0.9 pixel ratio, the width
    is 90% the height. They are taller than they are wide.

    But my monitor pixels are wider than they are tall. So the height is
    quashed down further than it really is !! You can do this test on
    your monitor. For example, I created a 400x400 image and viewed it at
    100% size on my screen. It measured 6.44" x 5.75" (WxH).

    The DV AVI pixel ratio of 0.9 is calculated by w/h. So my computer
    screen ratio = w/h = 1.12. But ratios of pixels are usually quoted
    at less than 1 so I will use the inverse ratio of h/w = .893 (the
    height is reduced by .893). So 480 pixels tall will be reduced in
    relative size to a width equivalent to 428.

    So for DV AVI's - theoretically, my screen will take a 720x480 image
    and display it at a size "equivalent" to to 720x428 for a W/H ratio of
    1.68 - I measured a 720x480 image on my screen to test this:

    Width x Height = 11.44 x 7
    W/H ratio = 11.44/7 = 1.63 (close enough to my theory - it is
    proved !!).

    The DV ratio has no effect on PC Monitors - whether you export a video
    clip using sqare 1.0 pixels, or rectangular 0.9 pixels - the video or
    exportes frame images show and play at EXACTLY the same resolution and
    size, because the screen has a fixed pixel size !! It always uses the
    same pixel ratios regardless. 720x480 shows on my screen as 11.44" x
    7" no matter what Premiere exports the video as.
     
    Ken, Nov 25, 2004
    #1
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  2. Ken

    deco_time Guest

    You never stated what resolution your screen is set at. To get thoses
    result, I'm gonna guess 1280x1024, which is 5:4 aspect ratio, and not
    4:3; 1280x1024 is the only resolution considered standard with that
    weird aspect ratio.
     
    deco_time, Nov 25, 2004
    #2
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  3. Ken

    Jeff Makey Guest

    To solve this problem on my CRT monitor I brought up a square image
    and adjusted the monitor's physical display controls until the image
    was square as measured by a ruler. As a result, at 1280x1024
    resolution I have black bars about 1/2 inch wide on the sides of my
    display. On those occasions when I switch to 640x480 the black bars
    are on the top and bottom, letterbox style.

    This is the way to do it when undistorted images are more important
    than using every square millimeter of your CRT screen.

    :: Jeff Makey


    Department of Tautological Pleonasms and Superfluous Redundancies Department
     
    Jeff Makey, Nov 25, 2004
    #3
  4. Ken

    deco_time Guest

    A monitor is physically 4:3, why not just choose a resolution that's 4:3
    to begin with? Just use a resolution of 1280x960, instead of weird
    distorted aspect ratio.
     
    deco_time, Nov 25, 2004
    #4
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