1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Welcome to Lightroom Forums! We're a friendly bunch, so please feel free to register and join in the conversation. If you're not familiar with forums, you'll find step by step instructions on how to register and post your first thread under Help on the menubar above. You're also welcome to join our newsletter, download our free Lightroom Quick Start eBook and explore our other FAQ resources.
    Dismiss Notice

Exporting: pixels per inch / cm?

Discussion in 'Lightroom General Discussion (ARCHIVE)' started by hp5rebec, May 13, 2009.

  1. hp5rebec

    hp5rebec New Member

    Joined:
    May 13, 2009
    Messages:
    4
    Hello,

    Plebe here.

    I shoot with a Nikon D-8' in RAW format. When I export images, they default to 24' pixels per inch. Is this sufficient? I guess what I want to know is:

    (1) Does this default to 24' regardless of image size? Is this a function of image size, or does it vary but is not related to image size at all?
    (2) When is it good to modify this? I'm assuming that if I'm exporting to print a smaller image, I might not need that level of detail.
    (3) Does it ever make sense to increase this?

    I never know what to do with this field.

    Thanks!!
     
  2. Denis Pagé

    Denis Pagé Lightroom Guru Lightroom Guru

    Joined:
    Nov 1, 2007
    Messages:
    3,016
    Location:
    Boucherville, Québec, CANADA
    Lightroom Experience:
    Power User
    Primary OS:
    Mac 10.11.x El Capitan
    Lightroom Version:
    6.6 / CC 2015.6
    Lightroom License:
    CC Subscription
    Welcome to Lightroom Forums Plebe!

    Until you go to paper, it is all meaningless and can take any value so, (1) is your closest answer and "not related to image size at all". This is no more than a declared value that can be changed later without altering file size or resolution. What is giving you the resolution is the number of pixels you can get. Screens know nothing about inches and just care about the number of pixels so for them, pixels per inches make no sense.
     
  3. hp5rebec

    hp5rebec New Member

    Joined:
    May 13, 2009
    Messages:
    4
    If I'm exporting to a JPEG (from a RAW), however, can't I reduce the pixels per inch, even though I'm not printing it? Seems to me it's just a way to modify the resolution. This is similar to my scanner, which asks me what dpi (essentially pixels per inch) resolution I want.

    Also, if it's meaningless at that point, why is this field editable? LR should just grey the field out.

    Basically, I want to export it with the most amount of detail as possible. I'm guessing that I cannot increase the pixels per inch ever, but in some circumstances I may want to reduce the pixels per inch.

    Thanks for the response, BTW.
     
  4. Replytoken

    Replytoken Senior Member

    Joined:
    Dec 7, 2007
    Messages:
    1,519
    Location:
    Puget Sound
    Lightroom Experience:
    Intermediate
    Primary OS:
    Windows 7 64-bit
    Lightroom Version:
    5.6
    Lightroom License:
    Perpetual License
    To briefly answer your comments.

    1 - The box does not modify the file's resolution. It is only an "advisory instruction" (metadata) that some software might read.

    2 - Many of us would love to see this field grayed out, or removed all together! But, it is there for programs that will use the metadata when they read the exported file.

    3 - You are correct on both accounts.

    My advise would be to just ignore the field.

    --Ken
     
  5. Brad Snyder

    Brad Snyder Lightroom Guru Lightroom Guru

    Joined:
    Nov 20, 2007
    Messages:
    6,293
    Location:
    Port Deposit, Maryland USA
    Lightroom Experience:
    Intermediate
    Primary OS:
    Windows 7 64-bit
    Perhaps it's an Lr urban legend, but we're told by old timers that this field is editable in order to allow photogs to please down stream users; clients, art directors, etc. whose only knowledge of resolution is that is should be some optimum number of pixels per whatever. There was a clamor to make it 'settable', even though it has no meaning in this context.
     
  6. Denis Pagé

    Denis Pagé Lightroom Guru Lightroom Guru

    Joined:
    Nov 1, 2007
    Messages:
    3,016
    Location:
    Boucherville, Québec, CANADA
    Lightroom Experience:
    Power User
    Primary OS:
    Mac 10.11.x El Capitan
    Lightroom Version:
    6.6 / CC 2015.6
    Lightroom License:
    CC Subscription
    No. It just tell to use that much of paper for that many available pixels. This value can be changed anytime without affecting resolution. Take an image of 2''' x 3''' pixels and make it 1ppi then print... :shock: really want to spend 64428 8½" x 11" sheets? Now make it 3''ppi and you need just one sheet (6.6" x 1'"). But in any case, you still have 3''' x 2''' pixels!

    Scanning is a completely different context as the scanner does manipulate physical things having measurable dimensions. A paper having a mesurable width by a mesurable height, an object you can take with your hand to put on its surface, a film slide Xmm x Ymm etc.

    In this case, the question is this: "For each given length of the scanned medium, how many pixels do you want?".
     
  7. Mark Sirota

    Mark Sirota Lightroom Guru Lightroom Guru

    Joined:
    Oct 8, 2007
    Messages:
    4,055
    Location:
    Philadelphia, PA, USA
    Lightroom Experience:
    Power User
    Primary OS:
    Mac 10.8.x Mountain Lion
    Lightroom Version:
    5.5
    I think that's right.

    I think it's also there because LR has to write something in that metadata field, and rather than just make something up they're asking the user.
     

Share This Page