Putting images inside a book
An image that looks perfect on your screen can print as a soft, muddy rectangle, and nothing warned you. Screens are forgiving and generous with color. Paper is neither.
The habit to build is this: stop thinking about how an image looks, and start thinking about how big it will print, in inches, and what ink will print it.
Resolution is measured at print size
A printed image needs roughly 300 pixels per inch at the size it appears on the page — not at the size it appears on your monitor, and not at the size the file happens to be.
Do the multiplication once and it stops being abstract. A photo that fills a 6×9 page needs about 1,800 × 2,700 pixels. A half-page image on that page needs about 1,800 × 1,350. An inline diagram three inches wide needs 900 pixels across.
Two traps follow. A screenshot is almost never enough — a 1,200-pixel-wide window is a four-inch image at print quality. Enlarging is not a fix: resampling upward gives you the pixel count without the information, and the print shows softness and a visible texture along hard edges.
If an image cannot make its size, you have two honest options — print it smaller, or find a better source.
In the Interior Formatter. Every image is checked against the size it will actually print at, and you get a warning when one falls short — before the file goes to a printer, not after a proof copy arrives. Start a book → · about the Interior Formatter
Inline images or plates
Two ways to put pictures in a book, and they behave differently.
Inline images sit in the flow of the text, with type above and below them or wrapped around them. They belong where the picture is part of the argument — a diagram in a how-to, a map at the head of a chapter, the photograph the sentence is talking about. They make pagination harder: an image that will not fit at the foot of a page pushes to the next one and leaves white space behind.
Plates are full-page images, usually grouped in one section. That is the traditional treatment for photographs in a biography or a history, and it exists for a print reason — plate sections could be printed on different, better paper. Grouping also stops the images fighting the text for space.
Choose by use. If the reader needs the picture at the moment they read the sentence, it goes inline. If the pictures are a gallery supporting the whole book, they can be plates.
Bleed, margins and the gutter
An image can sit inside the margins, framed by white like a block of text, or it can bleed — run off the edge of the trimmed page with no margin at all.
Bleed is not a switch you flip. The blade that trims a stack of pages wanders slightly, so a bleeding image must extend past the trim line — typically 0.125 inches on every bleeding edge — and that extra is cut away. So you need image beyond the picture you want, and a print service that accepts a bleed interior; one bleeding page usually means the interior is set up as full bleed throughout.
And remember the binding. An image near the gutter loses its inside edge into the spine, worse in a thick book than a thin one, so faces, captions and scale bars must sit clear of the inside margin. A two-page spread loses a strip down the middle: use it for landscape and atmosphere, never for a face or a line of text.
The black-and-white problem
Most print-on-demand interiors are printed with black ink only. Color interior printing exists, and it costs several times more per copy.
So a color image in a black-and-white book is converted to gray, and the conversion throws away exactly what the color was carrying. A chart where the red line means revenue and the green line means cost becomes two lines of the same gray. A photograph built on a red door in a green field flattens into one tone. The image is still there; the information is gone.
Convert deliberately and look at the result. If a figure relied on color, rebuild it to work in gray: different line weights, dashes and dots, labels sitting directly on the lines, distinct fill patterns rather than distinct hues.
There is a billing trap too. An image that is nearly but not quite neutral can still be counted as a color page — a scan with a faint warm cast, or a logo left in RGB, is enough. Convert to gray yourself rather than assuming the printer will read your intent.
Captions, credits and alt text
A caption belongs with its image, on the same page, never stranded on the next one. Keep captions in one consistent style — a size smaller than the body text is usual — and number figures if the text will refer to them.
A licensed image needs its credit. Stock licenses, museum images and other people's photographs usually carry a required attribution line, and the license says where it must appear. The caption works, a credits page in the back matter works; leaving it out does not.
Alt text is for the EPUB. It is what a screen reader announces in place of the image, and without it the reader hears nothing at all. Write what the image conveys, not what it contains: "chart: sales double between 2019 and 2024" is useful, "chart.png" is not.
Images make the file big
Every image lands in the EPUB at full weight, and a photo-heavy ebook can run to tens of megabytes. Some stores take a delivery fee out of your royalty by file size, so images are not free in an ebook the way they feel. Size each one for its job rather than shipping the camera original.
In the Interior Formatter. Images come straight out of your .docx — inline, full-page plates, bleeding to the edge or across a two-page spread — and your alt text carries through to the EPUB while the interior ink is set for black-and-white printing. Start a book → · about the Interior Formatter
Finish the interior before the cover
Here is the sequencing rule, and it is the one people break.
Images change the page count — a plate section adds sixteen pages, an inline image that will not fit pushes text forward. The page count sets the spine width, and the spine sets the size of the whole cover file.
So: place the images, compose the interior, take the final page count, and only then build the cover. Do it the other way round and you will build the cover twice. See Spine width.
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: How to format a book interior · Back to Widows, orphans and rivers · Also: EPUB vs print PDF · Spine width