What is overscan?

Discussion in 'Projectors, Screens & Video Processors' started by ManuB, Sep 15, 2007.

  1. ManuB

    ManuB
    Active Member

    Joined:
    Jan 7, 2007
    Messages:
    295
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    London, UK
    Ratings:
    +16
    Hi,

    While calibrating my projector I came over a setting called overscan which I don't understand.

    I'm using a BR disc to set sharpness, one of the screens there let you calibrate the image to fit exactly in your screen.
    In the cornes you have arrows indicating the image format 16:9, 4:3, etc...
    To fit the 16:9 size in my screen I need to set the overscan to the max, otherwise it's not visible.

    In the manual of the projector you can only read that pushing the overscan to the max could affect the sharpness of the borders.

    Did I position my projector wrongly that it doesn't show the full 16:9 screen, or what is overscan all about?
     
  2. spooney

    spooney
    Active Member

    Joined:
    Oct 2, 2006
    Messages:
    2,252
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Location:
    Seyring
    Ratings:
    +204
    Hi,

    overscan is a historical feature. It is some extra image area around the image which usually is not seen. It has been introduced for TV broadcasting to make sure the edges of the image are straight and not somehow distorted.
    On a pj it means you cut out a few lines (+1 = 1 line) around the image.


    Sometimes when viewing NTSC material on a PAL pj, e.g. music DVDs transferred from VHS or older film material, you may notice a strange white line top or bottom of the image. The image edges look like not perfectly fitting together.
    If you turn on overscan this distortion disappears and the image looks perfectly framed.
     
  3. nwgarratt

    nwgarratt
    Distinguished Member

    Joined:
    May 5, 2002
    Messages:
    27,785
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +3,190
    MY W100 has no overscan as default when using the DVI socket (same on the IN72 from what I have seen). I get the same with some PAL DVD's on the left and right side of the picture. I also got it around all four sides with the R1 Fast and teh Furious DVD. It took some time to get use to but it is better overall when I am seeing more of the picture at the sides.

    ManuB, here is what no overscan looks like. It was one DVD that didn't show the lines down the side. What I also had to get used to was becuase the no overscan made a wider image. It made the black borders slightly bigger so the actual picture wasn't quite as high as before. Notice the component picture is slightly taller. It also created borders on 1.85:1 films that had no borders before due to overscan pushing it off the screen.

    Overscan (component)
    [​IMG]

    No Overscan (HDMI - DVI)
    [​IMG]
     
  4. ManuB

    ManuB
    Active Member

    Joined:
    Jan 7, 2007
    Messages:
    295
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    London, UK
    Ratings:
    +16
    Thanks a lot guys :thumbsup::thumbsup:

    It's funny because to obtain what you show on the last shots I need to put Overscan to the MAX.

    If I set overscan to 0 I'll obtain what you have on component, if I set it to 10 I'll obtain what you have on HDMI.

    I must admit that I only have HDMI sources connected to the projector through a HDMI switch.

    There is a difference between the PS3 and the HUMAX Sat, on the PS3 Overscan on 10 will show me a perfectly fitting 16:9 image while on the HUMAX I'll get black borders all around, there I need to lower the Overscan to 5 to get it fitted.

    So I guess there is no absolute Overscan setting for all sources, I'll need to play with it on a case by case basis.

    Thanks again for superb explanation :smashin:
     
  5. nwgarratt

    nwgarratt
    Distinguished Member

    Joined:
    May 5, 2002
    Messages:
    27,785
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +3,190
    Afaik, it is expected/assumed that how something handles overscan can be different on different devices.
     
  6. spooney

    spooney
    Active Member

    Joined:
    Oct 2, 2006
    Messages:
    2,252
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Location:
    Seyring
    Ratings:
    +204
    You are right. I remember a few threads were people were struggeling with component vs HDMI pciture ratio.
     
  7. ManuB

    ManuB
    Active Member

    Joined:
    Jan 7, 2007
    Messages:
    295
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    London, UK
    Ratings:
    +16
    I'm changing case by case my overscan, PS3 on +10 and Humax on +5, both on HDMI.

    This week I'll be connecting my component devices, we'll see what they require :rolleyes:
     
  8. pragmatic

    pragmatic
    Well-known Member

    Joined:
    Nov 9, 2004
    Messages:
    12,150
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    133
    Ratings:
    +1,647
    Is overscan making the component picture look less sharp or is it just that your HDMI output is better?
     

Share This Page

Loading...