Way back in mid-March, we closed our office as a precautionary measure in response to COVID-19, and since then I have been planning (and planning and planning) to write about Pressbooks and the ways open digital technologies, open content, and open practices can be part of a resilience strategy in the face of upheavals like
By Zoe Wake Hyde
At Pressbooks, we often get questions about how to make sure the images in your book are print-ready and ebook-perfect. To address some of the most common queries and offer some guidance on how to manage your images even before you upload them to Pressbooks, we’ve developed this short FAQ. It should address most questions, but if you’re still not sure of anything, let us know! We’re always here to help — just email email@example.com.
What size should my images be before I upload them into Pressbooks?
It depends! If you’re only making an ebook or webbook, anything from 300 x 300 pixels and upwards should generally work. However, if you’re going to be printing your book, you’ll need to be a bit more careful.
As a basic rule, you should take whatever size in inches you want the image to be and multiply it by 300 to get the pixel dimensions. So, if you want an image to appear at 3in x 5in, it should be at least 900px x 1500px. THEN when you insert it into your chapter, select the option for full size. If you insert it at a smaller size (e.g. large or medium), the system will compress the image and it won’t print well.
Also keep in mind the upload limit, which is 2MB per image, and your overall storage cap. You can read more about these limits here.
But the media editor lets me resize images–why can’t I just do that?
Like any software, the Pressbooks media editor can only make your images smaller, not larger. There’s no way for it to add more detail to an image! The best way to resize your images is to go back to the original and work from there.
Should I add my images to my chapters at full, large or medium size if I’m doing a print book?
For print, images should always be inserted at full size to ensure the highest possible image resolution. The smaller size options compress the image, meaning it won’t be exported at the highest possible resolution.
How do I control the exact location of an image on the page–for instance, in a photo spread or photo book?
This kind of image placement is not possible with Pressbooks. It is for this reason we don’t recommend Pressbooks for photo books, children’s books or other image-heavy book genres, which are better served by a traditional option like InDesign.
How do I upload just one image for both ebook and print? I need it to be high enough quality for print, but also not make my file so big it incurs ebook digital delivery fees.
Your best option when you’re working on print and ebook simultaneously is to make sure everything is up to standard for print, then use the automatic theme option to compress your images for your ebook export. To do so, go to “Appearance” → “Theme Options” → “Ebook Options” and select “Reduce image size and quality”, and your next ebook export will contain compressed versions of your images, reducing the file size. (But your print image sizes will remain the same.)
If I’m just doing an ebook, what size (resolution and dimensions) should my images be?
If you’re only working on an ebook, image quality is much less of a worry than for print because screens require a much lower resolution (so are more forgiving to lower quality images!), but it still pays to be careful. The general guide is to imagine how big you want an image to appear on screen in inches, and multiply that by 100 to find the best size in pixels to upload. So if, on screen, you want a small 1.5in x 1.5in image, it only needs to be 150px x 150px when you upload it (so long as you set it to full size!).
I put in a 300 dpi image but it didn’t stay that way. What gives?
The first thing to check is the dimensions in pixels of your image. If you’re seeing the image file marked as 300dpi, it’s important to know that that is just a piece of metadata, and doesn’t actually impact how the image appears on the page — DPI can be very misleading!
If you’ve checked the dimensions of your image (you can do this by going to your media library and clicking on the relevant image to see the details) and they are in fact large enough, the next thing to look at is the size at which your image was inserted. You can do this by clicking on the image, then on the grey pencil icon that appears to open the image editing screen. Here, you’ll see an option to change the size, which should be full size.
If both of these things are in order but your image is still being flagged as less than 300 dpi, email us at firstname.lastname@example.org and we’ll help you out.
How to Upload Images in Pressbooks
Zoe Wake Hyde is a publishing innovation & technology whiz and mans the Pressbooks support desk. If you email us with a question, you’ll probably run into her! Watch out for her regular posts on the Pressbooks blog, giving advice on updates, new features and common formatting challenges.