TL;DR — The file details that matter for printing a poster are simple once explained: resolution (aim for ~300 DPI at your print size), format (a high-quality JPEG or a print-ready PDF both work), and colour space (most shops handle standard RGB or convert to CMYK themselves). This guide demystifies the terms so you can hand a file to any printer with confidence.
By Found Poster · Published October 2026
Resolution and print size go together
Resolution only means anything in relation to size. A file has a fixed number of pixels; printed small they pack tightly and look sharp, printed large they spread out and soften. The working target is about 300 pixels per inch (DPI) at your final size — so a file meant to print at 16×20 inches needs far more pixels than one for a postcard. Our files state the sizes they print sharply at, which removes the guesswork.
JPEG, PDF and TIFF
For a photographic or restored image, a high-quality JPEG is perfectly good for printing — the compression, at maximum quality, is invisible in a print. A PDF is useful when a file needs a fixed layout or exact dimensions, and most print shops accept both happily.
TIFF is an uncompressed format sometimes preferred by professional printers; it makes larger files but discards nothing. If a shop asks for one, it is a sign they know what they are doing. For most people at most shops, a high-quality JPEG at the right size is all that is needed.
Colour: RGB and CMYK
Screens show colour in RGB (red-green-blue); printing presses use CMYK (cyan-magenta-yellow-black). The difference sounds technical, but in practice most modern print shops and fine-art printers accept a standard RGB file and manage the conversion themselves, often with better results than a hand conversion. Unless a printer specifically asks for CMYK, send the file as supplied.
What to send, in practice
For almost every case: send the full-resolution file as supplied, tell the shop the size you want, and ask them not to auto-sharpen or colour-correct. That is the whole brief. The formats and colour spaces are handled behind the counter; your job is only to start from a file built for the size you want to print.
Every file in the archive is supplied print-ready, with its recommended sizes noted. Browse the archive →
Frequently asked questions
What resolution do I need?
About 300 DPI at your final print size. Because resolution depends on size, a large print needs many more pixels than a small one; each file notes the sizes it prints sharply at.
JPEG or PDF for printing?
Either works at most shops. A maximum-quality JPEG is fine for a photographic image; a PDF is useful when exact dimensions or layout matter.
Do I need to convert to CMYK?
Usually not — most print shops accept a standard RGB file and convert it themselves. Only convert if the printer specifically asks.
Further reading
Found Poster restores Belle Époque and Art Nouveau posters from museum archives into archival-quality files you print yourself. Browse the archive · How to print & frame.
