TV zoom mode: loses resolution?

Discussion in 'Archived Threads 2001-2004' started by Marc Rochkind, Mar 31, 2002.

  1. Marc Rochkind

    Marc Rochkind Second Unit

    Aug 26, 2000
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    I understand from some posts in the "sources" area that when a non-anamorphic image is zoomed (to, for example, fill a 16:9 screen with a letterboxed image), that the scan lines are just blown-up, so that they are spread farther apart.

    An example of this is a Toshiba's Theaterwide 2 mode.

    To be more precise: The incoming signal has 480 lines, but the 1.85:1 part in the middle has only 346, so in Theaterwide 2 zoom mode there are only 346 lines on the screen, losing 134 lines of vertical resolution.

    Can someone confirm that this is what actually happens, and that the TV is not doing something smarter, such as lopping off the 134 lines and then RESCALING the image back to the full 480?

    Clearly the first approach is easier and cheaper for the TV manufacturer, but are there TVs that do it the more complicated way?

    (In the other thread it was pointed out that it is better to zoom in the player, which I am aware of. My questions are about what the TV is doing, not about where is the better place to do it.)
  2. Allan Jayne

    Allan Jayne Cinematographer

    Nov 1, 1998
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    Using optical zoom, 360 of the 480 scan lines fill the 16:9 screen assuming no overscan. The 1.85:1 picture was already reduced to 346 lines of resolution vertically during the disk recording process. (A 1.77:1 non-anamorphic picture would occupy 360 scan lines.)
    If the TV upscales the picture instead of spread out the scan lines, the 1.85:1 picture now occupies approximately 460 scan lines but the vertical resolution relative to the source material is still 346 lines, or maybe a few less depending on the quality of the upscaling. Upscaling does not increase the resolution of the source material.
    I do not know what TV sets do the zoom which way. You might be able to tell by auditioning the TV in a store.
    Video hints:

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