Displaying photos on display with non-square pixels

Discussion in 'Digital Photography' started by Phill, Sep 24, 2005.

  1. Phill

    Phill Guest

    I know this has come up before here and I've read the posts but haven't
    found a solution to my problem.

    I want to display my pictures on a 1280x768 pixel screen with phyical
    dimensions of of 16:9. The pixels are not square. This means if I make
    a perfect square, say 100 x 100 pixels, it appears to be 6.67% wider
    than it is taller on my screen. So, in my case, the TV really does add
    20 pounds.

    I found a post about HardView picture viewer that claims to be able to
    stretch images for display automatically and therefore get arround the
    problem. Unfortunately, I can't download it, I can only presume that
    MrMills is no longer developign the viewer. Is there a viewer that can
    take care of this for me.

    I'd prefer not to have to batch resize my photos to compensate as they
    would then all have the wrong aspect ratio for displaying on anything

    Any help would be greatly appreciated.

    Phill, Sep 24, 2005
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  2. Phill

    Marvin Guest

    An image 1280 pixels wide would have to be 720 pixels high to have a 16:9 aspect ratio.
    If you force the image to have an aspect ratio of 16:9, there has to be some distortion.
    If you want the picture to fill the screen undistorted, you need to crop the picture to
    the 16:9 aspect ratio. B.t.w., there is no such thing as a non-square pixel.
    Marvin, Sep 24, 2005
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  3. Marvin wrote:
    Actually, a pixel can be any size of shape you want. It is only by choice
    that most pixels are nominally rectangular, of equal horizontal and
    vertical size, and presented on a rectilinear grid. Some Fuji cameras
    have a grid at 45 degrees to the horizon. HDTV uses non-square pixels.

    David J Taylor, Sep 25, 2005
  4. Phill

    Jukka Aho Guest

    SDTV, too. (While there are no "pixels" in analog broadcasts, DVB, DVD,
    SVCD, VCD, DV, Digital Betacam, and digital production facilities -
    everything that is connected together using SDI - all use sampling
    matrices with non-square pixel aspect ratios.)
    Jukka Aho, Sep 25, 2005
  5. And at least according to dpreview's review of Canon EOS 5D, Nikon D1X
    used a CCD with rectangular pixels half as wide as they were high.

    Jan Böhme
    =?iso-8859-1?B?SmFuIEL2aG1l?=, Sep 25, 2005
  6. Phill

    Phill Guest

    I was afraid of starting this old debate about pixel shapes. I have a
    Pioneer PDP-503CMX. Honestly, it has rectangular pixels, they are
    0.858x0.808 mm in shape.


    ^Scroll down to pixel pitch

    It's native resolution is not in the same ratio as it's physical
    dimensions so if you display a perfect circle it looks oval on the
    monitor . There are a few plasma TVs on the market which are like this
    and if you connect them to a PC and give them something to display at
    their native resolution it looks great but it's distorted. If I'd have
    done the maths before buying it, I'd have bought the Panasonic.

    For watching movies, I use zoomplayer, which has a setting to adjust
    the aspect ratio of the image to compensate for non-square pixels. I
    just need an image viewer with a similar function.

    I don't fancy downloading and installing every freeware and shareware
    viewer I can find until I find one that does it. Since you guys have
    probably got or have used a rang of viewers, could you just check to
    see if your viewer can do this and if so I'd love to hear from you.

    Phill, Sep 25, 2005
  7. Phill

    Marvin Guest

    And somehow those pixels must be transformed to work with, for example, a monitor with
    square pixels, or there will be distortion.
    Marvin, Sep 25, 2005
  8. Phill

    Ray Fischer Guest

    Of course, but programs like Photoshop allow for non-square pixel
    aspect ratios.
    Ray Fischer, Sep 26, 2005
  9. Phill

    Phill Guest

    That's right, there is embeded information (EXIF, I believe it's
    called), that allows an image viewer to account for the pixels in the
    image not being square and even to have a default size to print out at.
    Since most computer minitors have sqare pixels and the operating system
    assumes you have square pixels on you display, that's usually
    sufficient. This is a different problem to the one I have.

    My problem is that the display device doesn't have square pixels. It's
    not actually a problem with the imges, which is why I don't like the
    idea of distorting the images to compensate or editing the EXIF
    information to fool the image viewer into reshaping the image.

    Perhaps I haven't made it clear that I'm trying to display the images
    on a large screen, rather than preparing them for printing.
    Phill, Sep 26, 2005
  10. Unfortunately, almost all displays in the computer/digital photography
    realm use square pixels, so most tools for viewing images support only
    that. In the video world, where pixels are almost always non-square,
    software that resamples as necessary is routine.
    One suggestion: you might ask the author of Irfanview if he has
    considered supporting non-square pixels. Irfanview already contains
    quite high-quality resampling filters, and it can resample at different
    ratios for horizontal and vertical so you can explicitly resize images
    for correct display on your screen. Further, Irfanview can
    automatically resize images to fit the screen as it's going through a
    directory full of images.

    Given all this supporting code already in place, I suspect it would
    take only a few extra lines of code to support automatically resizing
    for non-square pixels. Most of the work adding support for this would
    probably be in adding a pixel aspect ratio option to the Properties
    menu. From what others have said, the author of Irfanview has a good
    record of incorporating user suggestions in new versions of the software.

    Dave Martindale, Sep 27, 2005
  11. Phill

    Phill Guest

    Thanks Dave, I'll drop the Irfan an email and see what he says.
    Phill, Sep 27, 2005
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