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martinb94379230
martinb94379230
Known Participant
June 3, 2017
Answered

DPI / resolution & photo quality for print.

  • June 3, 2017
  • 2 replies
  • 1187 views

I am creating a small print "magazine" with fan photos for a Facebook community that I run. I have only worked with Photoshop for a few months so please bear with me here. What I need is to make sure that people send me photos that are good enough for print and that I don't end up with 100 photos and have to tell everyone that their photos weren't good enough and that they have to shoot them again with different settings.

Is it correct that asking for a "300 dpi photo" for example makes no sense? Do I basically just ask for photos that are of a sufficiently high resolution instead and then I am at least as "safe" as I can be when it comes to print? 

PS I am trying to come to a better understanding of dpi/resolution, but no need to explain that here - I will research that further on my own and try to come to a better understanding in time (actual printing is months away still). Right now I just need to make sure that the photos I receive from everyone are good enough.'

Thanks in advance!

    This topic has been closed for replies.
    Correct answer D Fosse

    The first table is fine.

    It's just a question of doing the math. Given so many inches, and so many recommended pixels per each of those inches...that gives you the pixel dimensions you need to satisfy that particular ppi requirement at that size.

    Of course, there's no need to pull out your pocket calculator or reach for tables. You can just use Photoshop's Image Size dialog. Put in two parameters, and the third comes up by itself (but make sure "resample" is unchecked!!!).

    It should be emphasized here that ppi requirements are usually not absolute. A lot of people are convinced that anything for print must be 300 ppi. But this is just a common myth. Firstly, there's nothing magical about that number. Nothing bad happens if you go below. If it happened to be 290 instead of 300, you wouldn't be able to tell the difference. It just so happens that 300ppi is the theoretical upper limit for standard book and magazine print, above which no improvement is possible.

    Secondly, ppi requirements depend on viewing distance. It drops rapidly as you move further away from the print. For wall-sized banners, you can often go as low as 20 ppi. Dave (davescm) has a nifty little formula for this, which I can never remember from one day to another . In reality, this is about angle of view - how many degrees of arc the image occupies in your total field of vision.

    2 replies

    martinb94379230
    martinb94379230Author
    Known Participant
    June 3, 2017

    I found this guide: Printing images - what file size do you need? Resolution, pixel sizes and file sizes explained and compared for print

    Would this still be a proper guideline in your opinion? According to this, for an 8 x 10 print I would need to request 2240x1680, 4 Megapixel in order for the photos to translate into a print quality this website considers optimal quality (photo quality).

    Does this seem reasonable?

    D Fosse
    Community Expert
    D FosseCommunity ExpertCorrect answer
    Community Expert
    June 3, 2017

    The first table is fine.

    It's just a question of doing the math. Given so many inches, and so many recommended pixels per each of those inches...that gives you the pixel dimensions you need to satisfy that particular ppi requirement at that size.

    Of course, there's no need to pull out your pocket calculator or reach for tables. You can just use Photoshop's Image Size dialog. Put in two parameters, and the third comes up by itself (but make sure "resample" is unchecked!!!).

    It should be emphasized here that ppi requirements are usually not absolute. A lot of people are convinced that anything for print must be 300 ppi. But this is just a common myth. Firstly, there's nothing magical about that number. Nothing bad happens if you go below. If it happened to be 290 instead of 300, you wouldn't be able to tell the difference. It just so happens that 300ppi is the theoretical upper limit for standard book and magazine print, above which no improvement is possible.

    Secondly, ppi requirements depend on viewing distance. It drops rapidly as you move further away from the print. For wall-sized banners, you can often go as low as 20 ppi. Dave (davescm) has a nifty little formula for this, which I can never remember from one day to another . In reality, this is about angle of view - how many degrees of arc the image occupies in your total field of vision.

    martinb94379230
    martinb94379230Author
    Known Participant
    June 3, 2017

    Great, thanks for the thorough explanation. That is quite helpful in coming to a better understanding. I will play around more with these settings to get a better feel for it.

    But right now basically I will just ask people for a minimum of 2240x1680 resolution - and then mention that the camera has to be minimum 4 megapixel - although I'm guessing that probably pretty much any camera today is more than 4 megapixel.

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    June 3, 2017

    Ppi means pixels per inch.

    So yes, ppi is meaningless without a physical print size to apply it to.

    Ppi is a simple equation. Once you get to grips with what pixels per inch means, literally!, it all falls into place. Like any other equation, it can be inverted and rearranged, so that any two parameters will give you the third.

    martinb94379230
    martinb94379230Author
    Known Participant
    June 3, 2017

    Thanks for your reply. The print size will be that of a regular magazine, for example like People Magazine which I believe is around the size of other common newsstand magazines (8” x 10 7⁄8” or something close to that). Bearing that in mind, what specific guidelines could I give to our fans who will contribute photos to be on the "safe side" when it comes to printing? Should I just say, send us your photos in minimum resolution of .... x ..... ?

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