A file size tells only part of the story.
Megabytes can be misleading. What matters more is the image’s pixel dimensions and how large the artwork will be at its placed size. A wide image may have enough information for a small landscape panel but not for a full-width poster. A portrait may fit a page until a tight crop removes the pixels that were supporting a face, product label or fine texture. Keep the original image where possible; a resaved or compressed copy is rarely a good replacement for the source.
Ask what the image has to do on the page.
Not every image needs the same level of detail. A soft background can behave differently from a photograph that needs to show fabric, a brush mark, a map label, a piece of jewellery or a person’s expression. Look at the important part of the crop, not only the image as a whole. If the point of the photograph is a small feature, inspect that feature at the intended physical size before the layout is treated as ready.
Crop and enlargement change the answer.
Designers often make an image more useful by cropping it. That can also make it less suitable for print if the crop leaves too little pixel information for the printed area. The same is true when a small image is enlarged to fill a spread, a catalogue block or a cover. Keep a note of images that are being enlarged heavily, used across a fold or paired with close-up captions. They deserve an early conversation rather than a surprise at proof stage.
Mixed image sources deserve different treatment.
A book, catalogue or calendar may combine commissioned photography, scanned artwork, supplied brand assets, screenshots, web downloads and phone images. Do not assume that one acceptable file means the whole folder is ready. Flag the source of each important image, whether it has been edited, who owns the rights and where it is intended to appear. A small image used as a reference or decorative stamp may need a different decision from the hero image that carries a whole page.
Use a real-size check; the monitor cannot show everything.
Large displays can make a low-detail image look more convincing than it will feel in print. If practical, make a working crop at the intended physical size or print a representative section at that scale. Look at the part a customer will hold close: small text inside an image, edge detail, a person’s eyes, a product texture or a fine illustration line. This is not a substitute for the agreed proof route, but it helps an editor, designer or author spot the images that need better source material or a different placement.
Give the image set a short, useful record.
For an image-led project, a simple sheet can prevent hours of guessing. Record the filename, source, intended page or panel, crop direction, key detail, rights/contact point and any question that remains open. A photography editor may own the selection; a marketing manager may own product images; an author may own supplied family photographs. Naming those responsibilities keeps the print conversation focused on the image that is actually being used.