How to use Testcard G

Discussion in 'General TV Discussions Forum' started by ramayana, Jul 24, 2002.

  1. ramayana

    ramayana
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    Anybody out here know how to use the so-called Testcard G or know any link that explains how to use this testcard.
     
  2. Zacabeb

    Zacabeb
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    If it is the Philips pattern you mean...
    [​IMG]

    ...then I have a blueprint I made with the different kinds of test signals pointed out, that can be found here (~100kB JPEG, 767x575).

    This refers to the original PM5544 pattern that was crafted by Philips (and Bosch?) in 1972. There are variants used with modifications, especially to the frequencies and levels of the definition lines.

    I wondered a few years ago what was in the Philips pattern, so I tried to investigate things by phone - and managed to come across a white paper on the very original PM5544 generator made in 1972. Based on that I made a Philips pattern that can be found further down.

    Some points of interest:
    • The bars on either side of the circle all have ~50% luminance and will have the same shade of gray when color is turned down. They are used to check for proper color decoding when servicing a set.
    • The reflection check lines can be used to look for ghosting and incidentally also for SVM and processing artifacts.
    • The color bar inside the circle is normally 75% contrast, 100% saturation and can be used fairly well for adjusting color saturation.
    • The sinusoidal definition lines show the resolution and how well the TV suppresses cross-luminance. On a set with a comb filter, they should all be sharp.
    • The yellow and red bars at the bottom of the circle can be used to detect phase errors between luminance and chrominance.
    If it is the newer Snell & Wilcox Test Card you are after, there is some nice information on it at the Snell & Willcox website: http://www.snellwilcox.com/internet/reference/testchart.html

    Bonus: The Test Card G in an insanely high resolution, for use as a desktop pattern. (~111kB JPEG, 1536x1152)

    Does the BBC still use Test Card G?
     
  3. ramayana

    ramayana
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    Thks, Zacabeb...

    It's the Philips test patter and is what I'm looking for

    Question...

    Do I expect to adjust my screen until I see all the testcard pattern exactly like the picture you post, ie should I see the all of the checker pattern at all edge of the testcard?
     
  4. Zacabeb

    Zacabeb
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    You should adjust it so that it cuts the checker pattern, somewhere between the outer edge of the grid and 1/4 inside the outermost squares. Some sets are factory adjusted to cut more, but it may also result in logos and captions being partially cut.

    [​IMG]

    The grid in the test pattern is not 1.33:1 but 1.308:1, so you may see some of the checkers on either side if you adjust the picture to get the circle proportions right.
     
  5. ramayana

    ramayana
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    Thank you very much for your help.
     

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