The 600-pixel logo for a 300 mm banner
A customer brings a logo into your print shop on a USB stick as a JPEG measuring 600 x 400 pixels. They want it printed 300 mm wide across the top of a roll-up banner that will be read from about one metre away. The file looks crisp on the shop monitor at 100% zoom, and the customer insists it is high quality because a professional designer made it. They ask you to enlarge it in your image editor and print it. Your press operator runs banner work at 300 ppi, and the banner also carries one line of small contact text that must stay legible.
1. Calculate the effective resolution of the supplied file at the requested print size and decide whether it can be printed as delivered.
Read the worked answer
Effective resolution at the requested size
- 300 mm = 11.81 inches
- 600 px / 11.81 in = about 51 ppi
- The press needs 300 ppi, so the file is roughly one-sixth of the required pixel density.
- Pixels needed at 300 ppi: 300 x 11.81 = about 3543 px wide (~3543 x 2362 px to keep the 3:2 shape).
Verdict: not printable as delivered at 300 mm. Enlarging in the editor only interpolates - the software invents pixels by averaging neighbours, so no new detail appears. Edges go soft, the JPEG compression artefacts already in the file are magnified, and the small contact text (the most detail-critical element) degrades first. A large photo might survive 100-150 ppi at one metre viewing distance; small text will not.
2. What should you request from the customer, and in what order of preference? Justify each option.
Read the worked answer
- Vector original (AI, EPS, SVG or PDF with live text) - best option. A vector redraws at any size with no pixels involved, so 300 mm, 3 m or 30 m all print sharp, and the text stays crisp.
- Native layered raster file (PSD or TIFF) at print size - acceptable if it is at least 3543 px wide and has not been repeatedly saved as JPEG.
- A fresh PNG or maximum-quality JPEG exported at 3543 px wide from the original - workable fallback, but JPEG is lossy; every re-save throws away more data, so ask for the first-generation export, not a copy of a copy.
Explain to the customer that the on-screen sharpness at 100% zoom only proves the file is fine for screens, not for print - screen and press have different resolution requirements.
3. Nothing better is available. What is the largest size at which this exact file can be printed at a true 300 ppi, and what practical options do you offer?
Read the worked answer
True 300 ppi limit: 600 px / 300 ppi = 2 inches = 50.8 mm wide. Anything wider is interpolation.
Realistic options to offer:
- Print the logo at ~50 mm and rebuild the banner around it - keeps it genuinely sharp.
- Apply the viewing-distance rule: at one metre, roughly 100-150 ppi is often acceptable for imagery, which would allow about 100-150 mm wide - still short of 300 mm, and small text would still fail.
- Redraw or have the logo redrawn as vector - the only option that meets the 300 mm brief with legible contact text.
Do not simply upsample to 3543 px and call it 300 ppi; the file would carry the right pixel count but the wrong amount of detail.