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Anamorphics stretch- lose resolution?

Discussion in 'Televisions' started by willowbob, Oct 19, 2002.

  1. willowbob

    willowbob
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    It is quite apparent on my 36ZP18 Toshiba that when viewing an NTSC signal or pal signal and selecting "Cinema" setting I.E. when vertical stretching occurs, that there is a loss of resolution and this is visually apparent- you can just about detect the lines horizontally when they have been stretched apart.

    You probably know this already.

    My question is WHY IS IT NOT THE SAME FOR ANAMORPHIC HORIZONTAL STRETCHING OF THE PICTURE?

    I can't detect any loss of resolution in the vertical lines and no gaps appear.

    Some people say there is "HIDDEN" vertical information that fills in the spaces when you stretch anamorphically.Some say this is false.

    WHAT IS THE TRUTH?
     
  2. rct

    rct
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    The truth is that no horizontal stretching occurs with anamorphic material... the image is actually a 4:3 image which is compressed to form a 16:9 one.

    Say if there is a 16:9 picture which has a large circle in the middle of the screen. The image which is actually stored as 4:3 will appear as a vertically skewed oval on a 4:3 display that has no circuitry to compress the image and display it in the centre.

    Hope this makes sense.
     
  3. willowbob

    willowbob
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    But if you stretch a 4/3 image that isn't anamorphic , but still put it on the widescreen setting, no loss of resolution seems to occur and this didn't start out as a 16/9 picture
     
  4. rct

    rct
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    There you are stretching the image horizontally, not vertically.

    The loss of resolution apparent with non anamorphic material is because only the centre portion of the 4:3 frame available is used and this is stretched vertically to fill the screen, making the scan lines more apparent. In an anamorphic 16:9 picture, the entire 4:3 frame is utilised and then "squashed" to give a 16:9 image.
     
  5. willowbob

    willowbob
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    sorry, you misread...I said NO loss occurs with a 4/3 or 16/9 picture when you stretch it along the horizontal plane
     
  6. LV426

    LV426
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    It's because a TV picture is made up of horizontal scan lines, but not vertical ones. If you look closely at a colour CRT TV screen, you WILL see vertical stripes, but these are artefacts of the TUBE, not of the video signal. So, they don't move depending on the setting you use.

    Whereas the SIGNAL consists of horizontal scan lines. Stretch the image vertically (as you would with a letterboxed, non-anamorphic signal) and you separate the scan lines. So you see the gaps between them.
     

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