Preparing Images for Your e-Book

by | Oct 14, 2015

Last month I discussed how to clean up your manuscript to prepare it for ebook conversion. This time I’m going to be looking at how to do the same thing with images. [1]

There’s one big difference, however: where the advice that I gave you about getting your text squeaky clean was equally valid for preparing to convert your words to either print or ebook format, these suggestions are ebook-only.

What’s the difference?

Well, in either case, you’re going to start by finding the perfect picture to go with your words. You’re going to crop the picture (cutting out any extraneous bits) and enhance it (or get someone who knows how to do so) so that it looks beautiful.

However, there are two enormous differences between the image files you want to use in an ebook and ones you’re going to get printed on paper:

  1. In a print book, color is expensive, while in an ebook beautiful color costs (essentially) the same as black and white.
  2. On the other hand, in print, you want the image file that goes off to the printer to be as high quality (that is to say, large) as possible, while in an ebook, every kilobyte costs you (I’ll explain how below).

Use color — please!

As someone who’s been around the publishing industry for a long time, this conundrum was one of the hardest things for me to wrap my head around when I first started creating ebooks: that using color wasn’t verboten.

As you probably know, printing a book using even a single color image often more than doubles the production cost of the book. Why? Well, you know that your desktop printer has four colors of ink: cyan, magenta, yellow, and black (CYMK). And unless you tell it not to, it will print every page — even one with only black letters — using all four inks.

A professional offset printing press is essentially the same, though with the ability to use many more colors if needed. [2] A commercial print-on-demand press is exactly like your inkjet — except it’s built to work with much higher volume and with much more consistency.

So unless you do something really special (and expensive) like getting the printer to insert a single plate by hand into each book before it is bound, you’re going to be printing the entire book in full CYMK+ color. Ouch!

With ebooks, none of that is an issue at all! Many dedicated ereaders and all ereader apps used on computers, tablets, or smart phones display in three colors (red, green, and blue — RGB). There is no black pixel! And if you remember your high school science, white light is made up by shining all three colors at once. So color is (in most cases) the default. Why not take advantage of that?

Okay, so some Kindles and other ereader devices use an eInk screen that’s not in living color. These devices’ screens use much less energy, and many people find them easier to read, so there will be folks who will be viewing your beautiful, fully saturated snapshot as if it were being displayed on a 1984 Macintosh. As with those trailblazing computers, the eInk devices are still capable of displaying your picture beautifully — just not in color.[3]
 
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So one word of warning: do make sure that you look at every image in both color and grayscale before you convert it. A picture that looks crisp and clear in brilliant color can lose its contrast when seen in black and white.

Stepping on the scale

What ebooks give us in color, they take away in file size. When you send an image off to a printer or print designer, the idea is to send it at the highest possible quality, in a lossless format like TIFF (Tagged Image File Format, if you care). The files for my 36-page illustrated children’s book The Seven Gods of Luck weigh in at a healthy 128 megabytes (MB).

Many ebook retailers won’t even allow you to upload a file larger than 20MB. And even with those that do, such as Apple, you need to consider how many of your readers will be accessing your masterpiece: on a wireless device, where download speeds are slow, and empty space is taken up by cat videos and audio recordings of a niece’s singing recital. Nothing frustrates a reader more than buying your book — but not being able to download it.

On top of that, our favorite elephant in the room, Amazon, deducts fifteen cents per megabyte from every royalty payment as a “transport fee.” [4] (I always imagine a group of burly truckers carrying floppy disks with your ebook on them from a storage locker to the download bay on the other side of Jeff Bezos’s kingdom.)

So for a 20MB book, that would be $3.00. If you’re charging $9.99 (a high price by indie-published ebook standards), you’ve just lowered your royalty from 70% to 40%. If you’re charging less, the damage is even worse.

What can we do to avoid this catastrophe? What is the cause of all of this bloat?

Well, you’ll need to trust me on this: it isn’t your words. If you don’t believe me, look at this picture of the innards of an ebook:

Prepping images screenshot 1

These are the files that make up the text portion of an average-sized book (Joseph Campbell’s Myths to Live By; my paperback copy is 288 pages). See those numbers in the third column, the column headed size? They range from under a kilobyte, to 21KB — the total, including the front and back matter, is 104KB, or just over a tenth of a megabyte.

If you were to buy the ePub file of this ebook, you’d see that the file is actually somewhere around 4.2MB.

So where did the other 4.1MB come from?

A few kilobytes of it can be found in the stylesheets, navigation files, and such. But most of it came from the ninety-odd lovely pictures that I added when I was creating the ebook edition. [5]

Prepping images screenshot 2

Ouch. That’s sixty cents off the top of every Amazon sale. But the images were integral to the new edition, the first put out by the Joseph Campbell Foundation. So in they stayed.

So what’s a body supposed to do?

Taking a byte out of file size

Before we start our pictures on their weight-loss program, I need to explain something about images in ebook files: they have to be either JPEG or PNG (portable network graphics) files. No bitmap (.bmp) files, no vector (.eps or .ai) files,[6] no Photoshop (.psd) files, no raw camera (RAW or Exif) files. Just .jpg and .png files.

This turns out to be a good thing, because these two formats allow the most control over the final size of your image file.

We’re almost ready to start working with the images — but remember: never work with the original file. Always work with a copy, so that if something goes horribly wrong, all you’ve lost is a little time. Rename your working files. Put them in a different folder. On a different computer. In a different city. (And make sure that there’s a backup of the…. Oh, you know the drill.)

One of the most important, most technical jobs involved in designing an ebook is massaging the images so that they don’t take up too much space, but at the same time still display beautifully.

There are three parts to making that happen:

  1. Sizing (making sure that the height and width of the image are in the right range of pixels)
  2. Compression (using software to make the file as small as possible without losing quality)
  3. Optimization (getting rid of some unnecessary bloat that your image carries around with it needlessly)

Sizing

The easiest way to decrease the file size of your image is to decrease the number of pixels — in other words, simply making the picture smaller.

At this point most phones (let alone dedicated cameras) are capable of taking pictures over 10 megapixels — that is, ten million little collections of red, green, and blue dots. The native dimensions of a picture taken on an iPhone 5s like mine is 3264×2448 pixels.

Guess what?

Even a high-resolution Retina iPad can’t squeeze that many pixels onto its screen. Neither can a Retina MacBook 15”.

So, I ask, why include pixels that will never actually be seen by anyone not reading your ebook on a super-high-definition 30” computer monitor?

I’m going to assume that you’re used to working with a basic image editing program like PhotoScape, GIMP, or Apple Preview — if you can find your way around Adobe Photoshop (even an old version), this should be easy.

So. Open the file.

Wait — you aren’t going to work with the original image, are you? Good. Just checking.

In your app, find the menu item to resize the picture. In Photoshop, it’s under the Image menu: Image Size… In Preview, it’s under the Tools menu. In PhotoScape, click the Resize Photo button at the bottom of the window.

You’ll be shown a box that looks something like this (from PhotoScape):

Prepping images screenshot 3

You’ll see the existing width and height (in pixels, inches, centimeters, or whatever), with a box next to it to fill in a new measurement. Somewhere there will be something like that little check box in the picture above that reads “Preserve aspect ratio”; this will keep the height and width of the image proportional. Which is, usually, a good thing.

So what size should you set your image to?

It depends on a number of criteria:

  • How important is the fine detail of the image?
  • How many total images are there in the book?
  • Are the pictures primary, or are they secondary to the text?
  • How sharp is the image to begin with?
  • Is the image a photograph, a painting, or line art?

If the ebook is a picture book or a collection of photographs that you expect readers to examine closely, then by all means, keep the image as close to full-sized as you can. Still, there’s no point in making the image bigger than can be viewed on the device.

The short side on the largest current tablet screens (including the iPad and Kindle Fire HDX) is around 1600 pixels.

If you’re trying to keep your image as large as possible, then set the short side of your image to that size.

If, on the other hand, your picture is more decorative or illustrative than central, you might consider setting that short-side size to something closer to a standard smart phone or ereader width — between 600 and 800 pixels.

Click the “OK” button.

Suddenly, your picture will look tiny on screen. Don’t worry — you can zoom in to see it as it really is. Make sure that you don’t see any “jaggies” (ragged, pixelated lines instead of smooth, flowing ones), and that the important detail is all still visible. If you aren’t happy with the size you chose, go up to the Edit menu and select Undo — then try it again, until you’re happy.

Compression

Once you’re happy, you’re going to save the file, and when you do, you’re going to apply software compression — basically squeezing out the unneeded detail from the image, with the emphasis on unneeded.

At this point, I almost always save files in the JPEG format, since it is very, very good at compressing images.

We’re going to go up to the File menu and select Save As… (in Mac OS X Yosemite, they changed the label to “duplicate” for some reason). You’ll be confronted with a dialog box that looks something like this :

Prepping images screenshot 4

See that slider labeled “Quality”? That’s going to do the magic for us.

How much should you compress the image? As much as you can without compromising the quality of the image. Unfortunately, that scale isn’t calibrated uniformly — different software uses different compression algorithms at different settings. So you’re going to need to play it by ear.

I started out being very conservative in compressing images — close to the right-hand, “Best” side of the slider. At this point, I am often extremely aggressive, around the second tick mark from the left. If I’ve got multiple images in the book, I aim for each to be under 50KB, if I can help it. If this is the only, or one of the few images, I shoot for a file size in the 100–150KB range.

I then type in a new name — so that I still have the previous version, if I want to go back. Generally, I take the width that I choose in step 1 and add that at the end of the file name (that’s the -800 in the file name above) — oh, and I take out any spaces and replace them with hyphens or dashes, since ePub doesn’t like spaces in file names.

Then open the new photo — if it isn’t opened automatically — and see what the compression gods have wrought. Look for lines of gradation in smooth color bands (posterization), or jaggies. See if the detail in the image is still acceptable.

If not, or if the file is still too big, go back to the previous version (this is why you saved it!) and start again. [7]

Optimization

Now we get into some real black magic. Sort of.

Each image carries in it a bunch of metadata — information about when and how the picture was taken, the camera, the date and time, maybe the geolocation. If you’re trying to put together a slide show, this sort of information can be invaluable.
Locked inside of an ebook, it’s useless. And it can add as much as 20KB to an image.
There are several ways to strip this last bit of dead weight away. I use an open source (aka freeware) utility app called ImageOptim that gets rid of the metadata, as well as some other crud, without further compressing the file — Mac only, I’m afraid. In Windows, however, you can simply right click on the image file in Windows Explorer, click on the Properties tab, and then select the link at the bottom of the tab that reads “Remove Properties and Personal Information.” That should help — and it ought to slim down the file at least a bit. If you’re a Linux user, you can use the command line utility JPEGRescan (one of the ones on which ImageOptim is based).

Once you’ve gone through the whole process with each of your images (including the cover art), you’ll be ready to start making your ebook!


[1]Note that I’m not going to be talking about choosing images to accompany the text. I’m going to assume that you’ve spent a lot of time finding the perfect pictures to illustrate what you’re saying — and that you’ve made absolutely sure that you have the right to include them in your book.

[2]Okay. There are many more differences between a home printer and a large web press. Work with me here.

[3]Kindle vs. iPad by Zhao ! (@flickr.com) used through a Creative Commons license.

[4]This $0.15/MB fee applies only if you’re using the Kindle Direct Publishing 70% royalty rate, which you can choose for ebooks priced between $2.99 and $9.99. Go with the other option and you can charge whatever you’d like, and you won’t get charged a fee — but you’ll only make 35%. And that’s 4.1MB after I did all of the things I’m about to tell you to do. When I first converted the book, the Images folder was originally a bit under 14MB.

[5]And that’s not including another 15MB of lovely but ultimately unusable video. By the way, the 1MB that shows up attached to the Images folder? I forgot when I took this screenshot that I’d partially emptied the folder.

[6]You can, in theory, use Scalable Vector Graphics (SVG) files to do all sorts of nifty things in ebooks — but it’s a very difficult format to work in, and the format isn’t fully supported in all ereaders. Likewise, you can, in theory, use Graphics Interchange Format (GIF) files — even animated ones. However, Apple is the only retailer that will accept them.

[7]Be careful not to compress the same image too many times — if you open a JPEG and then select Save As…, you’re going to apply a whole new round of compression. Do that often enough, and your beautiful photo will start to look awful.

David Kudler headshot x 125David Kudler is a Contributing Writer for TheBookDesigner.com. He is also an author, an editor, an ebook designer and a writer for the Huffington Post.

You can learn more about David here.

 
Photo: bigstockphoto.com

tbd advanced publishing starter kit

79 Comments

  1. Does it matter

    I have been sitting her reading this article, and feeling more and more depressed. As if writing children’s books wasn’t hard enough, then having to del with taxes in TWO countries, because Amazon U.S. insists on taking 30% out for the IRS, even though they will return it anyway. A business license, because my province requires one. A French speaking Attorney, because the Quebec business office outright refuses to speak to me in English.

    I just deleted every word doc and image I had related to my books. I’m done.

    Reply
  2. Judy Henry

    Hello David.
    I chanced upon your column and I must say it seems to me you certainly know your business and I appreciate all assistance given regarding the ‘how to do’s’. I’m new to all this ebook publishing and after reading and attempting to absorb all the above I think I’ll have a Bex and a good lie down; that’s how old I am.
    I’m using BookWright and have almost completed a photobook with text descriptions but they ask me to resize my front and back cover (front has picture…back has text). So does this mean I return to my original front page image, do the 3 steps and then re-import it into the book?
    Thank you David,
    Judy

    Reply
    • David Kudler

      Thanks, Judy, and welcome to the wonderful world of digital publishing!

      First things first: ebooks don’t have a back cover. The “cover” is simply an image that gets displayed next to the description in online stores like Amazon or Apple — and that typically is dropped in as the first page of the ebook itself. Unlike a physical book, which a browser may turn over in order to find out more, no one’s ever going to see the back of your ebook.

      The de facto standard size for ebook covers is dictated by Amazon’s specs: a minimum of 2400 pixels tall and 1500 pixels wide, with a 1.6:1 height-to-width ratio. It’s a little skinnier than a typical print book (a 6″x9″ paperback, for example, has a 3:2 or 1.5:1 ratio), but it fits into Amazon’s pages nicely.

      So you need to create a cover image with more than those minimal dimensions.Save at the highest possible quality (that is, least compression).

      However, the one that you embed in your ebook should indeed be optimized according to the rules I laid out above. No reason to bloat your book!

      Reply
  3. Alan Turnbull

    Excellent article, thanks. Indirect question: can you direct me to instructions or suggestions on how to format labels for images for Kindle e-Book? Something like, “Figure 1: Some Description” along with how to set up hyperlink to figure from its associated text.

    Reply
  4. Eloise

    great info! I have written a couple of children’s books and I am entering the ebook world… I need to figure out how to add the illustrations to create something magical for the kiddos out there… this is a very helpful post, thanks!

    Reply
  5. The Scribe

    Great informative article thank you.

    I didn’t realise re the colour images leading to the whole book being printed in colour!

    Or, how much Amazon deduct for too large files sizes.

    I am still laughing at
    ‘Rename your working files. Put them in a different folder. On a different computer. In a different city. (And make sure that there’s a backup of the…. Oh, you know the drill.)”

    How many times should I have heeded that advice in the past!

    Reply
  6. Ted

    I am completing a biography of my more than 50 years roaming the earth as an exploration geologist. i have found that the younger generations don’t pick up books anymore so i am preparing an ebook with lots of images.
    Thank you for your easy to understand article of how to minimize imagery as to size. It is well written and works very well with all sources of imagery.
    My question to you is when I am done with the few hundreds of pages of text as well is *should I convert it to .pdf and if so how does that affect the resolution if one wishes to enlarge any image?

    Reply
  7. lori

    Wow, great article. I search HARD for this info on the web but your article was the only one I could find that nailed the answer to the question about ebooks and file size. I was shocked when I found out my image heavy crafts design book was going to cost me a whopping $4 to “send” to the customer on Amazon!~ In the process of writing a new book and your article is invaluable in helping me to get it right this time!

    Reply
  8. Letitia

    Awesome post! Thank you so much:-)

    Reply
  9. Kristina Kaine

    I have my original images/diagrams in word documents and when converted to pdf they are blurry. Can you recommend a way of converting them for my ebook to give sharper lines?

    Reply
    • David Kudler

      Kristina, unfortunately, when you import images into Word, it re-sizes them and changes their resolution. So what you see in the PDF is what you get.

      The best option, as I mentioned above, is to start with images that haven’t been customized by Word.

      When you say your original images/diagrams are in Word, do you mean that they were created there? As in, you’ve created charts within Word that you’re trying to recreate?

      There are a few ways to extract such an image.

      Save your Word doc as HTML. That’ll create a folder with the extension .fld (for folder) that will contain the images that Word created.
      Set your monitor to the highest possible resolution. Then set the zoom in Word so that the image fills the screen. Then take a screenshot of it.

      That will give you images that you can optimize and import into your ebook.

      Reply
  10. Kally

    Hello David
    Thank you for this article.
    Is it possible to use one picture multiple times (as a chapter header for example) but only have its size be counted once in the size of the final file?

    Reply
    • David Kudler

      Absolutely — if you’re comfortable editing the ebook using HTML. If you use the same address (URI) for each instance, then you only need the one image.

      Most conversion tools will create a copy of the image file for each instance where it appears. Just go in and change the URIs, then delete the extra files (or in Sigil or Calibre use the “Delete Unused Media Files” tool).

      Reply
  11. Charlene Raddon

    David, I need help desperately. I have an ebook scheduled to go live May 27. Right now it is on pre-order. But I just discovered that it’s all goofed up. I created a title page so I could use a special font and an image that would be rejected by Amazon. I inserted the image onto my first page, the title page, and it pretty much fills the page. But after loading the file on Amazon, and looking at it in the previewer, I see that my title page image is only a quarter of the page instead of full page. How do I resolve this?

    Reply
    • David Kudler

      What kind of file did you upload to KDP?

      If it was a Word document… Well, there’s not a whole lot you can do. Word’s handling of images is wonky to begin with, and rather than set the image’s width/height proportional to the screen size, it sets it to a specific number of pixels.

      If you used an ePub file and are comfortable editing it, set the CSS for the image so that the width is 100% and the height is “auto”.

      Hope that helps!

      Reply
  12. Isabel Uys

    Hi David

    You seem to be an expert with e-books. Hope you can solve my problem.
    I am a South African author.
    I have a problem with unwanted shading marks which do not show in my Word document but are here, there and everywhere in my book when I view it on the Kindle Previewer! I have tried every possible way but cannot erase them.
    Please help!
    Kind regards from sunny South Africa.
    Isabel Uys

    Reply
  13. T Jacobs

    I create my artwork in Adobe Illustrator, then export as a .jpg, then create a multi page .pdf from the .jpg images. Is it still important to withdraw the metadata from .jpg images of the artwork when creating a .pdf from the .jpg images? I have chosen the 35% royalty rate on Amazon because I didn’t really understand the other options. I also use Amazon Kids Book Creator and import the .jpg images directly into the Kids Book Creator free app. What is your best suggestion? The pages that are output from the Kids Book Creator are not able to zoom once in the Kindle which bothers me. I am stuck with only popup windows of text within that program.

    Reply
    • David Kudler

      No, you don’t need to compress the images you embed in PDFs, especially if you’re opting for the 35% royalty. I think if the file gets too big, Amazon might choke on it, but I haven’t hit that limit myself.

      I have played around with the KBC a bit — as a way of creating quick and easy fixed-format ebooks from a PDF, it’s okay. It does have some short comings — the way it deals with images being one. Also, it doesn’t seem to be able to include hyperlinks, which I suppose I understand in an app for making children’s ebooks, but still, makes it… not much of an ebook, you know?

      Reply
      • David Kudler

        For anyone who’s interested, Kids’ Book Creator (and Comic Book Creator) essentially use the PDF pages as images and embed them inside of an ePub-like package. The text isn’t searchable, there’s no ability to add media… Not really much of an ebook, but at least they kind of work.

        Reply
        • corinne

          Dear David,

          Thanks for all this great info! For me as a beginner I’m not sure I understand following correctly: I’m in the process of an illustrated book for preschoolers and make the illustrations in Illustrator myself. So I assume there is no $0,15 fee per image?
          For Amazon’s KBC is the best option to go for Amazon’s 35% royalty fee?
          And save my pages ( they all include an image with little text) as pdf?
          Appreciate your feedback!

          Reply
          • David Kudler

            The fee isn’t $0.15 per image — it’s per megabyte of file size for the ebook, and it’s deducted from the royalty for each purchase.

            However it is only deducted if you are using KDP’s 70% royalty plan, which requires that you price the ebook between US$2.99 and $9.99.

          • David Kudler

            Oh — and so yes, the best choice MAY be for you to go with the 35% rate, but you should create the book and see how big it is once it’s uploaded to KDP. They’ll tell you in the price-setting screen how much you can expect to net both at the 70%-$0.15/MB rate and the 35% flat rate.

          • corinne

            Thanks David for your very quick response! I’ll dive into it. What if I want to price the book under $2,99? is the 35% rate best then?

          • David Kudler

            Corinne,

            If you price your book below $2.99 (or €2,99 or £1.99), you can ONLY choose the 35% option.

          • Corinne

            Thank you David

  14. Sara

    Just wanted to say thank you! This is exactly what I needed.

    The tip about getting rid of the metadata is extremely helpful. I wouldn’t have thought of that.

    Reply
    • David Kudler

      You’re very welcome, Sarah! Glad this was helpful.

      Reply
  15. Robby

    David, Thank you SO much for this post. For the past year I’ve been on and off trying to figure out how to get the tables and graphics from a print book to work with Kindle. This answered nearly all my questions. Thanks again!

    I do still have a related question: In Pages I have a nicely formatted table in my print book. How do you suggest turning this into an image? (So far my efforts have produced unsightly results.)

    Thanks again!

    Reply
    • Robby

      I see my question could have been better formed:

      How do I turn tightly formatted text from my Pages document into an image suitable for including in my ebook?

      Thanks again!

      Reply
    • Joel Friedlander

      Robby, have you tried taking an enlarged screenshot of the table? If you get the sizing right, you can reduce it to 300 dpi for printing and it should work fine.

      Reply
    • David Kudler

      Thanks!

      Actually, if you look at the dates, you’ll see it’s the other way around.

      I usually make sure that there’s a link to the original post — I forgot that time. Thanks for pointing it out!

      David

      Reply
  16. Douglas Jones

    Such a wealth of useful information. But I have a very basic question. When I import the photos into the word doc they look great on my computer screen, many are as small as 30-40 kb. When it is uploaded to Kindle (and then downloaded by the customer) will the photos look the same. In other words, is “what I see what I will get?”

    Reply
    • David Kudler

      Thanks, Douglas!

      As I believe I said in the article, no, the way that Word deals with images means that what you see is probably NOT what you get. It’s one of a number of reasons that I don’t directly upload Word docs any more.

      Instead I convert them to ePub using Calibre or Sigil (there’s a plugin that allows you to import Word docs directly), and then re-import the optimized and compressed files.

      Make sense?

      Reply
      • David Kudler

        Just to be clear:

        I re-import the optimized and compressed IMAGE filesThen I upload the ePub file to KDP

        Reply
        • Doug Jones

          David, thanks. Let me try this and see if I can do it. I appreciate the advice!
          Doug

          Reply
  17. Sameer Lalsare

    Many thanks David for this great article. I was looking for some guidelines on images in ebook, your article carries the exact information. Thanks again

    Reply
  18. KP Kwan

    Great article. Learn tons from you.
    One question. I am writing an e-book to be published on Amazon. It is a recipe book and I intend to have images for every recipe, which will add up to about 100.
    Since images are absolutely important for cookbook, I am worry about the file size even I resize, compress and optimize each of them.
    Do you advice me to keep the image size to half of the page? I would love to use full page images.
    Thanks.

    Reply
    • David Kudler

      KP,

      Thanks for the great question.

      The choice is entirely up to you! It’s all a matter of what you’re willing to give up to Amazon for the larger images.

      Myths to Live By, which I referenced above, has over 120 color images, ranging in size from just about 100KB to some under 1KB (some icons and logos). The sizes generally are 1024 on the short side for the bigger pictures — and they’re otherwise squeezed using the tricks I outlined above. That left me with 4MB of images in the ebook. That adds up to about $0.60 off the top of every sale on Amazon, but it’s worth it in terms of the value added to the book (in our opinion).

      Reply
  19. seanie blue

    Great article, but one small conflict: in the article you twice refer to the shortest side of the image needing to be 1600 px, but in one of your replies to a comment, you refer to the longest edge of the of the image needing to be 1600 px. I am sure you mean longest edge at 1600 and not the shortest edge, correct? I use Lightroom (which is cheap and far superior to Photoshop for photographers), and outputting an image at a 2×3 ratio (for a 6″ by 9″ size) with all metadata stripped out yields the following sizes for 1600 on the shortest edge, which I believe to be incorrect advice:
    2×3 ratio image full color at 1600 px on short edge at 20% of quality is 202 kb.
    2×3 ratio image full color at 1600 px on short edge at 10% of quality is 165 kb.
    2×3 ratio image full color at 1600 px on short edge at 5% of quality is 150 kb.

    The good news is that these images are almost indistinguishable from one another if viewed at normal reading distance. In close-up, with your face less than 8 inches from the screen the degradation is bad on all these pictures but terrible on the 5%.

    When I put out the same image at 1600 px on the longest edge of the image, which I believe to be the correct advice, the following size are recorded:
    2×3 ratio image full color at 1600 px on short edge at 20% of quality is 126 kb.
    2×3 ratio image full color at 1600 px on short edge at 10% of quality is 106 kb.
    2×3 ratio image full color at 1600 px on short edge at 5% of quality is 99 kb.

    This is an image that is meant to bleed to the edges of the reader’s screen. An important aspect of changing space is to know what size the images need to be if they won’t fill the screen. For example on my table of contents, I use a small thumbnail linked to the page of the content I want the link to go to, and these thumbnails are perhaps an inch by an inch on the screen, so the image I use must be output at that size, instead of the 1600 px on either the large or short edge.

    So I wonder if you could confirm that you size your images to 1600 px on the short edge of your images? And have you had any experience with Blurb’s outputting of files for Kindle? They mention size limits, though they don’t mention the 15 cents per mg rate, and I wonder how efficiently they put your files into kindle-ready (or iTunes ready format)?

    Reply
    • David Kudler

      Thanks, Seanie — You’re correct, I should have put 1600 for the long side.

      I haven’t used Blurb’s output to Kindle — I don’t tend to trust PoD providers’ conversion. (But then, I wouldn’t.)

      BTW, many tablets and phones have an aspect ration of 16:9, rather than 3:2, so that’s closer to what I try to stick to.

      Reply
  20. Clive Maguire

    Excellent piece David – thanks, and lots of other good comments. However I find myself completely at a loss with what I thought would be something quite simple, and nothing here seems to enlighten me fully, and I can’t find your article on Word’s image handling.

    If anyone has a few minutes to save me from total insanity, I would really appreciate it….

    I have a series of simple tables, prepared in Gimp, with alternating blue/cream columns (following your advice, David :). They are quite small, and designed to be displayed centred on an ebook ‘page’. The tables themselves come out fine, but the text? Yeuch! I’m using Word to prepare the document, and it will be formatted in html by someone else (it’s beyond my ken at this stage). So what on earth am I doing wrong? Here’s my process:

    I have a separate png file for the table, which goes into GIMP as a layer. Then I type in my text as a separate layer (I’m using font League Gothic, but started with the GIMP-supplied Sans). Once I have everything looking good, I flatten the image and export it. I have the image sized at 300 x 175px at 144 pixels/inch, and I import the saved images to Word.

    Now, there are two things that are driving me mad – first of all, the gif images display okay in Word – at 1.82 x 3.13 inches, but the jpg displays much smaller – 1.22 x 2.08. Why? Next, I decided to check how the images looked in a pdf file (because I thought it would give me an idea of how they might look in an ebook), so I saved the document to pdf and… well, at 155% (the default opening size – why, I have no idea – the tables look great, but if I change the view to 100%, they all look crap. Why, oh why, and should I even care..? I don’t understand, and I don’t know what I should be doing now. Sans or League Gothic? Gif or jpg? Should I size in pixels and not care about Word, or should I size to get the right size in Word? Will I EVER get my ebook looking right, and what exactly is the meaning of life, universe and everything? Help please!

    Reply
    • David Kudler

      You’re not going to like this answer: Word’s image handling sucks. Word will resize and recompress images in ways that are incredibly unhelpful.

      I always import the images into the ebook after it’s been converted. That, unfortunately, requires that you edit the ePub file.

      Reply
      • Clive Maguire

        Thanks. In that case I’ll just carry on regardless, keep my nice images pristine and unsullied by Word, and sort it out later!

        Reply
        • David Kudler

          Afraid that’s the best way about it!

          Much success,

          David

          Reply
  21. Rod Fleming

    I think, given a background as an editorial photographer, that I would avoid saving to JPG or PNG in the initial stages of image preparation. These days we don’t want for storage.

    It is far better to work in TIFF, which is lossless, right up to the point you are happy with your work and are ready to drop the finished image into the page. Then just save to jpg or png and, if you have not already done so, strip out EXIF data. This avoids any risk of degradation due to repeated recompression by re-saving — remember that it’s not just when you close a file that the compression happens, it’s every time you save your work.

    Even if your file comes to you, or you originally saved it, as a compressed file, save your working copy as a TIFF or (if using Photoshop only) a PSD.

    Otherwise excellent and helpful. By the way, I know it’s an oldie but the best book ever written on picture editing for publication was Harry Evans’ Pictures on a Page. Most of it is still relevant today.

    Reply
    • David Kudler

      You are of course correct — TIFF is the best file format to work in while editing. One should re-save the file into JPG format once the cropping and color correction is done.

      Reply
  22. Harald Johnson

    Good post, David! But here’s a key question not covered (or I missed it): what is the SINGLE BEST aspect ratio for interior ebook images? For example, I’m making my own maps. I have to set the canvas to something so might as well set it to what’s best. Amazon keeps talking about 9:11 format, but that’s awfully square. Do you recommend 9:11? 3:4? 5:8? (again, I’m talking eBooks, NOT print; and a general guideline for ALL devices)

    Thanks!

    Reply
    • David Kudler

      That’s a tougher question than you’d think, because the phones and tablets most ebooks are read on vary so much. iPhones have a 4:3 ratio. Nooks, Kobos and Kindles mostly have a 1.6:1 ratio — so that’s the ratio I tend to use, especially with covers. But honestly, let he image decode the ratio if you can.

      Reply
      • Harald Johnson

        Yeah, I realize this is tough, which is why I’m asking. But good feedback, David. I’ll be testing both of these ratios. And I’m creating the images, so I’m the Decoder! :) Thanks. Appreciate it.

        Reply
  23. Kristen

    I just have to say thank you so very much for this incredible resource! I am in the midst of creating my first premium eBook for my site and this was just the information I was looking for!

    Reply
    • David Kudler

      You’re very welcome! I’m glad this was useful.

      Reply
  24. Bette A. Stevens

    Thanks for the detailed information. Bookmarking and sharing on Twitter as well.

    Reply
  25. Tracy Campbell

    Hi David,

    Thank you so much for providing a ton of detail. I found it extremely helpful as I’m currently tweaking a book with illustrations.

    I’ll be saving this info in my Evernote file.

    Thanks again,

    Tracy

    Reply
  26. Chris

    Thanks so much for the information, David. I do a lot of formatting for authors, but rarely books with images. I’m currently working on the Kindle and CreateSpace versions of a book for an author who has included just over 150 images in his historical book. I’ve been researching image sizes for Kindle books and the information I’ve found is conflicting. In one of their publishing guidelines, Amazon recommends using images with a resolution of at least 300 dpi or 300 ppi and saving at a quality level of 10 (with Photoshop) or higher. Other information I’ve come across says to use images with a resolution of 72 ppi.

    The author provided me with the images for the book and all of them are at least 300 dpi. They vary in size, so I need to edit each one and figure out the best size in pixels and resolution so they look good in the finished book. I also have to take into consideration that Word downsizes images if you save the file to web page filtered. It’s been a learning experience for me and thankfully the majority of books I format are all text.

    Reply
    • David Kudler

      Glad this was helpful, Chris.

      DPI is a meaningless measure when it comes to digital images. My monitor displays at 96 pixels per inch. Phones can have 160 pixels per inch or more. The question is, what are the dimensions of the image in pixels? And that’s where knowing the maximum resolution of a Kindle Fire (around 1600 pixels on the longest side) is important.

      I don’t like Word’s image-handling at all. So I tend to reimport images after I’ve done the conversion (the subject of this month’s up-coming post).

      Reply
      • Chris

        I’m looking forward to the post on reimporting images!

        Reply
  27. Maureen C. Berry

    David! You’re a gem. I’m glad to find you here. Thanks much. I’m finalizing a cookbook and have had more anxiety about the photos than is healthy! Now I’m off to find more of your fabulous, helpful articles.

    Reply
  28. Lynn Mosher

    The link for last month’s clean up guide isn’t working. I can’t find the article. Can you point me in the right direction?

    Reply
  29. Magi Nams

    Perfect timing! I released a non-fiction trilogy (POD) a few months ago and am in the process of transforming the manuscripts, each of which contains more than forty black-and-white photos, into e-books with colour pics. The photos have been the stumbling block, so I’m keen to try your suggestions. Thanks also for the heads-up about Amazon’s download fee.

    Reply
    • David Kudler

      You’re welcome! It’s great that you’re taking advantage of the color (sorry, colour) opportunities of the ebook!

      And yeah, the transport fee can be a shock — especially where you to release the trilogy as a box set.

      Reply
  30. Michael W. Perry

    My suggestion: Create two versions.

    For everyone but Amazon. Make the pictures look great, full-sized, high-dpi (I use 150 dpi), and little compression. Include additional pictures if you like. Give readers their money’s worth and more.
    For Amazon. Set a maximum file size and thus cost you are willing to pay, probably under 2 meg or 30 cents. Reduce the photos in every way possible to meet that goal. Don’t sweat the appearance. That’s Amazon’s fault.

    Then tell your readers that if they want good illustrations, they’ll have to go with a retailer other than Amazon, that you’re not going to pay Amazon’s inflated rates for what every other retailer offers for free.

    What Amazon is doing is a nasty, greedy racket. The download fee they charge is at least three times what cellular companies charge for data and ten times what Amazon itself charges its web service customers.

    I can’t understand why writers are such wimps. Amazon pays half what Apple pays for ebooks priced outside $2.99-9.99 and inside that range it charges these obscenely high download fees, which can knock another 10% or more off what authors get paid.

    Fight back. Shift as many of your readers to other platforms as you can. You’ll make more money and be more independent.

    Reply
    • David Kudler

      Agreed! The version I uploaded to Apple, Kobo, B&N, etc., of the Joseph Campbell book that I used as an example above was the full-quality, 15MB ePub.

      I’m going to be talking about the retailers in more depth in coming months.

      Reply
  31. Rosie McGee

    Fantastic article I wish had been available back in 2012 when I self-published my e-book with 200 photos! One tiny thing that may be helpful to those using these directions… If you have many photos to convert, as I did, you may want to divide your files into two folders – landscape and portrait (horizontal/vertical). Then, you can more easily use batch processing, if your software allows, to, for example, set the short-side size of the photos. I also found it helpful to write a condensed version of the process as a bullet list, so that you don’t get ‘lost’ in where you are in the process for a given photo. Believe me, after going back and forth a few times, it’s easy to get lost. Thanks.

    Reply
    • David Kudler

      Excellent suggestion, Rosie!

      Photoshop will auto-detect the longest side of an image — so if you batch resize a folder full of images to, say, 800px x 800px, Photoshop will resize the longer dimension to that size, and will resize the other dimension proportionally.

      However, other software doesn’t necessarily pull that particular trick, so your suggestion is an excellent one.

      Reply
  32. Michelle

    ImageOptim does not want to download on my Mac (OSX10.9.5)?

    Reply
    • David Kudler

      Were you ever able to get it to work? It downloads fine for me — I’m running Chrome on the latest version of Mac OS X. Have you tried a different browser? Sometimes that can help.

      Reply
  33. Alan Drabke

    Very good, very useful article. I use GIMP, but I had no probs following the dialogue. Since August of this year (2015) Calibre has been able to convert doc.x files to epubs! This is important because in addition to the conversion process Calibre will now flow text around tables. That’s a big help for people who insert their images into tables.

    Reply
    • Alan Drabke

      I forgot something! In addition to a cover image contest, The Book Designer needs a Facebook advertising image contest! (Maybe you all know this, but pictures of book covers included in a Facebook ad image are exempt from the 20% surface area rule.)

      Reply
  34. Alicia Butcher Ehrhardt

    Thanks. I’ve always wondered exactly what was happening with the compression part of the jpeg format – their choice of ‘best’ to describe the largest file has implications that everything else is second best – and who wants that?

    The other part, about stripping the metadata the user has no earthly need for, just to get rid of 20K – might be necessary in some cases. (I have a Mac.)

    I’ll have to pay attention. With a low resolution image, my epub is around 500K; after converting to .mobi, including the cover I intend to use (1800 x 2700), the file has swollen to 3.2M. This is not the way I want to go! It’s just a cover, however gorgeous I think it is.

    Reply
    • David Kudler

      You’re welcome!

      Do know that the mobi files that you download from Amazon is a Frankenstein monster — it’s got two ebook files in it: an old-style Kindle file and a new-fangled AZW3/ePub file. Only one of those will download to someone who buys the file on the Kindle Store, so you won’t get charged the full amount.

      To double-check this, look at the file size listed on the Kindle Store.

      Reply
  35. Anna Erishkigal

    Thank you! I knew most of this, but you gave me a new tip, very important when compressing box sets.

    Reply
    • David Kudler

      You’re welcome! Yes — box sets are a challenge, yes.

      Reply
  36. Karl Drinkwater

    Very useful, many thanks! Although I kind of knew some of this it is really handy having it in one place as a checklist. I had been working towards having a single master copy of my books (for both print and e-book) but this reminds me why that isn’t a good idea and I should have separate ones, at least when the book includes images (due to different DPI and file size requirements).

    I’ll go back to having different print and e-book versions for my latest novel, since images are included – it has an image introducing each chapter, but because of the issues with full bleed printing (a pain!) I am planning on breaking them down from 25 big images into about 120 smaller ones. This post means I’ll get it right first time for both the print and the e-book versions.

    Reply
    • David Kudler

      You’re welcome!

      It is a good exercise to think in terms of multiple versions — there are different needs.

      Reply

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