Using Photos in Your Book: Understanding Print Resolution

by Joel Friedlander on October 4, 2010 · 15 comments

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I was talking to an author the other day about photos he wanted to put in his book. I looked at the image files he had sent over with his manuscript.

“They look great,” the author told me, “I’ve put them into the book in Microsoft Word, I have it on the screen in front of me, it looks terrific.”

“Uhm, I don’t think these are going to work in your book,” I said.

“What do you mean, they seem fine to me? What’s wrong with them?”

What the author couldn’t see was that I hadn’t even opened the image files. I didn’t need to, all I had to do was look at the size of the files in the email attachment panel. One was 4k, the others were 8k or 10K or even 24k in size.

“Look, I explained, “there’s a big difference in what we use online, when you’re only going to be looking at them on a screen, and what we need when we go to print these same photos. I know it doesn’t seem to make sense, but the images you’re looking at on your screen are 72 dots-per-inch (dpi). We need files that are 300 dpi. And if they aren’t 300 dpi, there’s a good chance the printer will reject your job.”

Using File Size to Quickly Gauge Reproduction Size

I want to show you how to calculate this for yourself, even if you just want to be able to tell from the files you’re looking at if they are likely to work.

Okay, we’re going to do a little math now, but I promise it won’t hurt (too much).

Let’s look at the typical sizes of photographs or other grayscale images you might use in a typical book. I’ve taken a page from a 6″ x 9″ book and divided the space within the margins this way:

book design for self-publishers

Fractional pages. Click to enlarge.

  1. A full page illustration can be as large as 4.25″ x 7.6″ without going into the margins or bleeding off the page.
  2. A half page is 4.25″ x 3.8″
  3. A quarter page is 2.2″ x 3.8″

Now, taking what we know—that graphics have to be 300 dots per inch at their reproduction size let’s do some calculating:

  • Our full-page illustration will need to have:
    4.25″ wide x 300 dots per inch = 1275 dots, or pixels
    7.6″ tall x 300 dots per inch = 2280 pixels
    The photo that’s 1275 x 2280 will have a total of 2,907,000 pixels. That’s about 3 MB of data.
  • Our half-page illustration:
    4.25″ wide x 300 dpi = 1275 pixels
    3.8″ tall x 300 dpi = 1140 pixels
    So the photo will be 1275 x 1140 or a total of 1,453,500 pixels, or about 1.5 MB.
  • Our quarter-page illustration:
    2.2″ wide x 300 dpi = 660 pixels
    3.8″ tall x 300 dpi = 1140 pixels
    The photo will be 660 x 1140 or a total of 753,060, or about 800 KB.

Image Compression Makes a Difference

But wait. Most photos are saved as JPG files. Leaving aside for a moment whether this is a good idea (it’s not a good idea if you plan to keep editing the images). One of the reasons we use JPG online is for its ability to compress the files into much smaller sizes.

But it’s good to know what’s actually in the files. Let’s say we’ve saved each of our illustrations in both TIFF format with no compression, and JPG format with the compression set for maximum image quality. Here’s what our final file sizes look like, as reported by the Mac operating system:

  • Full page, TIFF: 2,989,336 bytes
    Full page, JPG: 841,578 bytes
  • Half page, TIFF: 1,560,237 bytes
    Half page, JPG: 537,242 bytes
  • Quarter page, TIFF: 844,607 bytes
    Quarter page, JPG: 351,015 bytes

And now you know why I knew many of this author’s photos were too small (and probably screen grabs at 72 dpi, way smaller than what’s needed for offset printing).

Even for a quarter page photo, saved with compression, the file size ought to be around 350 K. Obviously, photo files showing a file size of 50 K or 100 K will not be usable for a printed book.

By the way, this is another reason it makes sense to create the layouts and artwork needed for print production for your book before addressing ebook versions. You need the high resolution images for print. While it’s easy to reduce the size and resolution of your images, it’s not possible to add detail and data (or resolution) back into the image once it’s gone.

Takeaway: When planning to add photos to your book, make sure you have files with enough resolution to print at the size you want in the finished product.

Image licensed under a Creative Commons Attribution 3.0 License, original work copyright by See Ming Lee, http://www.flickr.com/photos/seeminglee/

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    { 13 comments… read them below or add one }

    Leah July 28, 2014 at 8:14 am

    Hi Joel,
    I’m working on a compilation book now where the contributors are sending in pictures of themselves to go with their bios. I’m getting mostly 72 dpi shots. I’m opening them in Photoshop and changing the resolution to 300 dpi, which is consequently upping the image size and file size to between 1 and 2.5MB. Do you think that’s sufficient to make the photos print quality? We’ll be printing through CreateSpace.

    Thank you so much for your blog – I’ve been googling lots of things lately and I keep being led back here. :-) You’ve been a great help!

    Best wishes,
    Leah

    Reply

    Joel Friedlander July 28, 2014 at 10:45 am

    Hi Leah,

    Unfortunately, the method you’re using won’t work very well. You can’t simply add image data by changing the resolution. What you’ll get are pixelated, low-resolution images even though you’ve “adjusted” the resolution because you haven’t actually created “print quality” image files at all :-(

    Reply

    Leah July 29, 2014 at 7:34 am

    Thanks for your response!

    Reply

    Monsieur Pelletier September 4, 2013 at 10:19 am

    Hey, Mr. Friedlander, what’s your last name? (lol)

    I need to know if a scanned print-out picture would hav e th e 300 dpi required for reproduction in an electronically self-published book. My book proposal for a traditional publisher was accepted but they required original quality prints, which would cost at least $1000 n half I couldn’t find. For my current book, most I wouldn’t be able to find, as original prints but they are all on the Internet, as with my previous book idea.

    Reply

    Joel Friedlander September 4, 2013 at 11:52 am

    Monsieur P,

    Your larger problem is contained here: “they are all on the Internet.” Unfortunately, you would have to request permission from the rights holders for each of the photos you find online. Once you get past that hurdle, you can address the resolution issue, but your publisher is correct in requiring original prints, for both permission and resolution issues.

    Reply

    Monsieur Pelletier September 4, 2013 at 12:26 pm

    So I would need original prints for the electronic self-publishing, too?

    Reply

    Tom Slaiter January 7, 2013 at 7:16 am

    Great post, I never really understood book print resolution till I read this!

    Thanks for the post :-)

    Reply

    Robert Nagle October 6, 2010 at 2:38 am

    I just finished writing & publishing a print book for CreateSpace involving a lot of web screen captures. SnagIt is a great & cheap tool for making screencaptures and upconverting images to 300 dpi. Here’s a video tutorial about the subject. http://www.techsmith.com/learn/snagit/10/video/print-ready/

    Basically I enlarged every image by 312% (300/96 = 312%)and then reset the image to 300 dpi. The original image captured by SnagIt is 96dpi. As long as the image isn’t full-page, you’ll be ok.

    Reply

    Joel Friedlander October 6, 2010 at 1:53 pm

    Robert,

    That was a really helpful video, thanks for that. Variations on this scale and reset resolution solution have been used for a long time to get the screen grabs that appear in books. It’s nice to have it so clearly explained. It’s too bad Snagit is Windows only, but it looks like a great tool.

    Reply

    Brian Dear October 4, 2010 at 9:21 am

    I look at this problem differently. If all you have is a low-resolution image, and it’s important it goes in the book, then what I want to hear from a designer is not “it can’t be done” but “let’s figure out a way to get it done.” I call it the Faroudja Response.

    Faroudja was the manufacturer famous in the 1980s and 90s for their verty expensive “line doubler” and “line quadrupler” gadgets that extreme videophiles used for their home theatres, where the state of the art at the time was laserdisc, which today looks like crap compared to DVD and Blu-Ray. But with a Faroudja box, you could process the low-resolution NTSC video signal and make it look much crisper with all sorts of fancy signal processing.

    The same needs to be done with images. When all you have is a low res 72dpi image — for example in my upcoming book, there will be numerous computer screen shots, which will by definition be 72dpi — and they have to go in the book, the last thing I want to hear from a designer is “no”. I want to hear “we’ll make it look good.” There are ways. Sometimes designers need to think more like engineers, and embrace the constraints, be creative, and come up with a solution.

    Earlier this year I had to put together a 24-page color brochure as a souvenir program for a computer conference. Lots of the images I had were crappy GIFs and JPGs, all 72dpi. The designer was not happy. The printer wasn’t happy. They wanted 150dpi minimum. Too bad, I said, that’s what you got, deal with it, make it look good. They did. The images look awesome. It can be done. 72dpi should not be a stumbling block for including images in a book.

    Reply

    Marcus October 4, 2010 at 12:15 pm

    Certainly there are ways. Not great, and not easy, but ways. But the point to be taken from the article is that you should provide high-resolution files whenever possible. So often, an author will paste an image into Word at some point in the writing process, and when it comes to the designer, all the designer gets is what’s in word. It’s really very easy for the author to send the original; they just need to know about it. So I think what Joel was explaining was how to know you’re going to need originals as early as possible, so that you can send the author on a quest to obtain/send the originals.

    Because, in reference to your last paragraph, keep in mind that you’re going to be significantly better off if you provide high quality originals instead of asking the designer to make low-resolution look good. Chances are you’re going to get charged for the time it takes to make the magic happen, which could be money saved if you plan ahead. So the point is just to plan ahead whenever possible.

    And yes, of course it’s not always possible. But 99% of the time it is. Maybe 72 dpi shouldn’t be a stumbling block, but refusal to obtain/provide 300 dpi when possible definitely shouldn’t be.

    Reply

    Joel Friedlander October 4, 2010 at 2:53 pm

    Marcus, thanks for your comment. I think you’ve got the gist of this exactly.

    Reply

    Joel Friedlander October 4, 2010 at 2:52 pm

    Hey Brian, thanks for your detailed comment.

    I’ve faced the same situation as a graphic designer, although I limit my work to books now. Last year I was called in to help on a catalog for a publisher industry group, only to discover the large photo on the front was 72 dpi and there was no way to either replace it or find the original. We did some magic and managed to get a good looking printing job out of it so yes, of course it’s possible.

    On the other hand, Brian, you have to realize that most self-publishers know nothing about printing or graphic arts. And a self-publisher throwing a book full of graphics at a designer and saying “deal with it” may (or may not!) get you decent looking images, but will probably also blow his budget right out of the water. How much better to get files with the right resolution from the beginning.

    The focus of these articles is education. Most of the self-publishers I deal with are using print on demand suppliers who run highly automated operations. And if the image files are not correct, they just bounce the book back to the client. The lesson here is to scale the reproduction size of your photos to the files you have available, not the other way around. That seems to me a good workflow, even though there may be times we have to deal with images that are not quite up to standards.

    Reply

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