Change resolution? Yeah right!

Discussion in 'Photoshop Tutorials' started by Borrox, Nov 9, 2005.

  1. Borrox

    Borrox Guest


    I am trying to put some stuff online and when I go to change the resolution
    to 72 it changes it from 150 to 149.9. What is going on? How do I make it
    change to 72. This has just started to happen. I have closed PS down and re
    done the scan and it still wants to only downsize it by 0.1!

    Can anyone please help, I am tearing my hair out here.

    Borrox, Nov 9, 2005
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  2. Borrox

    edjh Guest

    Resolution is irrelevant for online images. The resolution it displays
    at will be whatever the viewer's monitor resolution is.

    Use Save for Web and don't worry about it.
    edjh, Nov 9, 2005
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  3. Borrox

    Bill Hilton Guest

    Borrox writes ...
    First, what application will be displaying this image? Pretty much all
    the web browsers ignore the resolution (which is meaningful only when
    you scan or print), the size displayed on the screen is just the actual
    pixels. In other words a 600x400 pixel image at 72 ppi looks identical
    to a 600x400 pixel image at 400 ppi (or any other ppi).

    If you really do need to change this number (for printing or for an
    ignorant art director or just a personal phobia or whatever) just do
    Image - Image Size and uncheck 'resample image' and set the
    'resolution' value.
    This may be a scanner driver issue ... just change the resolution value
    *after* you scan with Image Size.

    Bill Hilton, Nov 9, 2005
  4. As a workaround, simply ignore the resolution. Browsers ignore it: they are
    only interested in the number of pixels.

    Andrew Morton, Nov 9, 2005
  5. Borrox

    edjh Guest

    NOTE: When resizing for web, determine what pixel dimensions (WxH)you
    need and resize accordingly in Image Size with Resampling checked. Then
    Save for Web.
    edjh, Nov 9, 2005
  6. Borrox

    Borrox Guest

    Hi guys
    Thanks all for replying and I really did not realise that the res was not so
    much an issue. I was always under the impression that images for online
    needed to be 72dpi. In fact when I was learning HTML there was a definite
    point made. Anyway, things change, so thanks for the update. I have just
    re-opened PS, scanned the same image done what I want with it and it let me
    change the res with no problem. What might cause this for future reference,
    although it may not now be an issue worth worrying about.
    Many thanks for you rapid replies.
    Borrox, Nov 9, 2005
  7. Borrox

    edjh Guest

    It's a common misconception. Older monitors commonly had resolutions of
    72 ppi; nowadays approx 96 is more common, but it doesn't really matter
    for web graphics.
    edjh, Nov 9, 2005
  8. Borrox

    sita Guest

    Hi guys,

    I like to know what is the real diffarence between no of pixels and
    sita, Nov 10, 2005
  9. The number of pixels is how many pixels there are.
    The resolution is how close together those pixels are, and consequently the
    size of each pixel.

    Perhaps try thinking of it like a mosaic - each tile is a pixel.

    Andrew Morton, Nov 10, 2005
  10. Borrox

    Jim Guest

    My system (and perhaps lots and lots of others) have the dpi set at 96.
    Thus whoever said that the online dpi needs to be 72 is in error.
    Jim, Nov 10, 2005
  11. So, when your TV picture goes all blocky, it's really tessellated. :cool:
    Roger Whitehead, Nov 10, 2005
  12. Borrox

    Bill Hilton Guest

    Jim writes ...
    You still don't get it ... this has no bearing on viewing web images
    since the browsers don't refer to it. So he could set the resolution
    to 96 ppi (not dpi, as you said) or 72 or 4000 and the image will still
    look the same on your screen. It's only a meaningful number when you
    print or when you scan.

    Bill Hilton, Nov 10, 2005
  13. SNIP
    For a specific output dimension, measured in pixels per inch/mm/etc.,
    that is.

    To elaborate a bit further, the pixels per inch (or dots per inch)
    metric isn't relevant when outputting with an application that
    physically disregards file embedded 'resolution' settings. On
    displays, each pixel should occupy a physical space equal to either a
    phosphor mask aperture, or an LCD picture element.

    Bart van der Wolf, Nov 11, 2005
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