An A2 Poster and a Square Social Tile from One Master
You are creating an A2 poster (420 × 594 mm) for a gallery exhibition; the same artwork will also be posted as a 1080 × 1080 pixel square on social media. You start with a new document: 420 mm × 594 mm, 72 ppi, RGB, and lay it out with a photograph, a large headline in a script typeface, a 9 pt caption block and a thin 0.5 pt rule around the border. Pre-flight at the printer reports the file at 72 ppi and rejects it for lacking bleed; they ask for 300 ppi, CMYK, 3 mm bleed and crop marks. Separately, the social media export looks wrong: the border rule has disappeared and the caption is unreadable on a phone.
1. State the settings the print master should have had, and explain what actually happens if you now just type 300 into the resolution field.
Read the worked answer
Correct settings: 426 × 600 mm (420 + 3 mm bleed on each side), 300 ppi, CMYK using the printer's profile, 8-bit, with crop marks and a 3 mm bleed offset. That is about 5031 × 7087 px.
Now the existing file: 420 × 594 mm at 72 ppi is only about 1191 × 1684 px.
- Type 300 with Resample off: pixel count stays the same and the document shrinks to about 101 × 143 mm. The layout collapses and every measurement is wrong.
- Type 300 with Resample on: you get 5031 px of interpolated mush. The photograph is soft with no new detail - though vector type and the rule would still render sharply, because they are re-rendered from paths at the new resolution.
So the professional answer is to rebuild at the correct trim size with bleed, place the photograph at a size its native pixels genuinely support, and only upsample the photo if the printer accepts it after seeing a proof.
2. Explain why the border rule vanished and the caption failed on the 1080 px square, and how you would produce that version.
Read the worked answer
Downsampling from 5031 px to 1080 px is roughly a 4.7× reduction. Anything thinner than about 1 px at final size is averaged away: a 0.5 pt rule at 300 ppi is only about 2 px, so at 1080 px it becomes well under half a pixel and turns into a pale smear. The 9 pt caption shrinks to roughly 2 pt equivalent - about 4–5 px tall - so anti-aliasing eats the letter shapes.
Judgement: a poster and a social tile are different designs, not one design at two sizes. Build a second artboard at 1080 × 1080 px and:
- drop the border or thicken it to at least 4 px;
- reset the caption to at least 28 px, cutting copy rather than shrinking it;
- crop the photograph square instead of squeezing it;
- check at 100% zoom on a phone, never zoomed out on a desktop.
Export from the master so type stays vector-sharp until the moment of rasterising, and never screenshot the print file.
3. The gallery owner asks why 3 mm of extra artwork is needed at all, and which elements should go into it.
Read the worked answer
Bleed exists because trimming is imprecise: ±1–2 mm of drift is normal on a guillotine. If a background stops exactly at the trim line, a sliver of white paper can survive on one edge, which reads as a mistake.
Extend into the bleed: the background colour or photograph, and any element meant to run off the edge.
Keep out of the bleed: text, the logo and the 0.5 pt frame. These sit inside a safe margin, commonly 3–5 mm inside the trim, or they risk being clipped.
Practically: make the photograph overflow the trim line, keep the frame as a live element well inside the safe area, switch on bleed and trim guides so you can see what will be cut, and export to PDF with 'use document bleed settings' and crop marks enabled. Then reopen the PDF, check at 100% that the marks sit outside the bleed box, and confirm nothing important is within 3 mm of the trim.