Start with Resolution, Not File Size

Most images that look wonderful on screen fall apart the moment they meet paper. The reason is nearly always resolution. Screens measure pixels per inch of display; print measures dots of ink per inch of paper, and the industry standard for sharp, detailed commercial printing is 300 pixels per inch (ppi) at the final printed size. A photograph that fills a 20cm-wide brochure panel, for example, needs to be roughly 2,362 pixels wide before you place it.

A common trap is judging an image by its megapixel count. A 12-megapixel photo sounds generous, but if you stretch it across an A2 poster, you are spreading the same pixels over four times the area and the effective resolution may drop below 100ppi. The result is soft, slightly blurry print that no amount of clever tweaking will fully rescue.

So do the sums first. Decide how wide the image will appear in centimetres, divide by 2.54 to get inches, then multiply by 300. That gives the pixel width you need. Check your source file before you commit to a layout, not after.

Resizing Without Losing Detail

If an image is too large, reducing it is straightforward and usually improves apparent sharpness. If it is too small, you are asking software to invent detail, and it will always be slightly softer than the real thing.

• Resample downwards in one clean step rather than a series of small reductions. Repeated resizing compounds softness.
• Never upscale beyond about 120% if you can avoid it. If a client insists on using a small image large, warn them in writing that it will look soft.
• Crop before you resize. Remove anything you do not need, then set the final dimensions and resolution together in one dialogue box.
• Keep the aspect ratio locked unless you genuinely want a stretched image. Squashed faces and oval wheels are the classic giveaway.

Remember that cropping reduces pixel dimensions too. Trim a third off a photo and you have a third fewer pixels to play with, which may push you below the 300ppi threshold for the space you need to fill.

Sharpen at the Right Moment

All digital images lose a little crispness during capture, resizing and printing, so some sharpening is expected. The trick is to do it after resizing, at the very end of your workflow, and to judge it on screen at 100% zoom.

There are broadly two stages. Capture sharpening compensates for the camera sensor and is best done in your editing software early on, gently. Output sharpening is tailored to the final medium and comes last. Print needs more sharpening than screen because ink spreads slightly as it hits paper, softening edges a fraction.

Aim for edges that look crisp but not haloed. If you can see a pale outline around a dark object, or a crunchy, gravelly texture in skin tones, you have gone too far. A useful habit is to apply sharpening, then toggle it off and on a few times. Your eye adapts quickly, and the comparison keeps you honest. For posters viewed from a distance, err on the side of restraint; for fine brochure detail read close up, a touch more is acceptable.

Getting Colour Right: RGB, CMYK and Profiles

Your monitor glows. Paper reflects. That fundamental difference means colours will never match perfectly, but you can get close with a sensible colour workflow.

Design software generally works in RGB, which suits cameras and screens. Commercial presses print in CMYK — cyan, magenta, yellow and black inks. Some RGB colours, particularly vivid oranges, bright greens and electric blues, simply cannot be reproduced in ink and will shift when converted. Converting early lets you see and correct those shifts before printing.

• Work in a consistent colour space, such as Adobe RGB or sRGB, and keep it consistent across all images in a job.
• Convert, then check. Look at saturated colours after conversion and adjust if something has gone muddy or dull.
• Embed the correct ICC profile when saving, or agree with your printer which profile to use. Many UK printers will supply one for their specific press and paper.
• Ask for a proof on the actual stock for anything colour-critical, such as branded packaging or product shots.

Also think about rich blacks. A flat 100% black can look washed out in large areas. A build such as 60% cyan, 40% magenta, 40% yellow and 100% black gives a deeper, more satisfying black — but keep small text in pure black so it stays crisp.

Choose a Sensible File Format

Formats matter more in print than most people expect. TIFF and PDF are the reliable choices for placing images and supplying finished artwork, because they preserve quality without compression artefacts. JPEG is fine for photographs, but save at maximum quality and avoid reopening and resaving the same file repeatedly, as each pass adds damage.

PNG suits logos and graphics with flat colour or transparency, though vector artwork is better still for anything with hard edges and text. Never lift an image from a website or a social media post — screen versions are low resolution and often compressed beyond repair.

A Simple Pre-Flight Routine

Before sending anything to print, run through the same checks every time. It takes minutes and saves expensive reprints.

• Confirm every image is at least 300ppi at its final placed size.
• Check that all images are in the same colour space and correctly profiled.
• Sharpen last, at 100% zoom, and check for halos.
• Look for accidental stretching, odd crops and stray white edges.
• Allow 3mm of bleed beyond the trim edge on full-bleed images.
• Save a flattened, print-ready copy and keep your layered original safe.

Get these habits in place and your brochures, flyers and posters will look reliably clean, sharp and true to colour — which is exactly what customers notice, even if they never quite know why.