The 72 ppi JPEG Sent to an Offset Printer
A student delivers a flyer for a stationery shop to a local offset printer. The file is a 1200 × 800 px RGB JPEG at 72 ppi, built in a photo editor with all the text typed directly into the image. The finished flyer must be 300 × 200 mm, trimmed, with 3 mm bleed on all sides, and the printer works in CMYK. The printer's one-line reply says 'file rejected - resolution and colour mode' and gives no other detail. The student still has the original layered file and one working day before the shop's reopening. The same design is to be reused as a 1080 × 1080 px Instagram post, and the shop owner wants the printed and the phone version to 'look exactly the same'.
1. Work out, with numbers, why the file was rejected and what the correct document size should be.
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Why it was rejected
- Effective resolution. The 1200 px width is spread across the 300 mm trim. 300 mm = 11.81 in. 1200 ÷ 11.81 = 101.6 ppi - about one-third of the 300 ppi offset standard. The 72 ppi tag is irrelevant; what matters is pixels per physical size, and this file has too few pixels for the size asked for.
- Colour mode. RGB has no CMYK separation. The printer's RIP would convert it, but the blacks and the saturated reds would shift unpredictably; a rich dark would come out muddy and the reds would dull.
- No bleed. The document has no 3 mm extra on each side; on a guillotine, the trim tolerance is about ±1 mm, so a white sliver will appear on at least one edge.
- Text baked into pixels. Retyping is impossible, the edges will be soft, and any spelling correction means rebuilding the whole file.
Correct document size
- Trim 300 × 200 mm; add 3 mm bleed on all four sides → 306 × 206 mm.
- At 300 ppi: 306 ÷ 25.4 = 12.05 in × 300 = 3614 px wide; 206 ÷ 25.4 = 8.11 in × 300 = 2433 px high.
- So the file needs roughly 3614 × 2433 px, not 1200 × 800 - about 3× the linear size and 9× the pixel count.
Practical note on the photo If only the 1200 px photograph exists, it can print at 300 ppi at a maximum width of 1200 ÷ 300 = 4 in ≈ 101 mm. Any larger and it must be upscaled and checked at 100% on screen before sending.
2. List the rebuild steps in order, with the settings you would enter, so the file passes on the second submission.
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Rebuild sequence (about 3 hours)
- New document
- 306 × 206 mm, 300 ppi, CMYK, 8-bit.
- Guides: bleed at 3 mm outside trim; trim at 0/0; safety margin 5 mm inside trim for all text and logos.
- Rebuild the image
- Bring the photograph in from the layered file at full size, not from the JPEG.
- Crop the photo inside the bleed on at least two edges so no white shows after trimming.
- Retype everything as live text
- Body text not below 8 pt; keep the shop name and the offer as the two top levels of a clear hierarchy.
- Nothing within 5 mm of the trim line.
- Convert and control colour
- Convert RGB to CMYK using the printer's profile if supplied; otherwise a standard coated stock profile.
- Large dark areas: rich black around C40 M30 Y30 K100. Small text and thin lines: 100K only, so misregistration does not produce coloured fringing.
- Total ink ≤ 300%; check the reds for out-of-gamut warnings.
- Export
- Press-ready PDF (PDF/X-4 or PDF 1.4), fonts embedded, images 300 ppi, bleed 3 mm, crop marks on, colour bars off.
- Send along with a 150 ppi low-res proof so the printer can confirm layout quickly.
- Confirm before running
- Ask for a soft proof or a laser proof; check the phone number, the address and the spelling of the shop name at 100%.
3. The owner wants the print and the Instagram post to 'look exactly the same'. How do you handle that request honestly?
Read the worked answer
Start by reframing, not refusing. 'Identical' is impossible because the media differ, but 'visually consistent' is achievable and is what the owner actually wants.
The differences the owner needs to know
- Colour. Offset prints CMYK on paper; the phone shows RGB in sRGB. Deep reds and bright whites cannot match exactly. Choose colours that survive both - mid-tone reds rather than the most saturated one.
- Shape. 300 × 200 mm is 3:2; the post is 1:1. Content cannot simply be squeezed.
- Size. The flyer is held at 30–40 cm; the post is seen at 30 cm on a 6-inch screen and scrolled past in about a second.
What you actually produce
- Print file: 306 × 206 mm, CMYK, 300 ppi, text ≥ 8 pt.
- Social file: 1080 × 1080 px, RGB/sRGB, exported separately. Keep the key message inside a 60 px safe margin so platform cropping does not cut it, and set the headline with a cap height of at least 30 px so it reads on a phone.
- Shared visual system: same typefaces, same two or three colours, same logo placement, same headline wording. Consistency comes from those decisions, not from exporting one file twice.
What you tell the owner Show both on screen side by side, then show the print proof. Explain that the shop will be recognised because the type and colours match, and that a squeezed 3:2 image on the phone would look amateurish and small. That is a stronger argument than a technical one about colour spaces.