The 300 ppi Banner That Prints Soft
A designer builds a 24 in × 36 in poster in Photoshop. The New Document dialog was set to 300 ppi, but the Width/Height units were left on Pixels, so the canvas is 300 px × 300 px. A client-supplied logo was placed as a linked Smart Object at 400 px wide and scaled down to fit. Separately, a photo layer was rasterized, then enlarged 400% with Free Transform, and the designer is now confused why it looks mushy. The file must go to a printer who requires 300 ppi at final trim size plus 0.125 in bleed on all sides.
1. What actually went wrong with the document dimensions, and how should the canvas be rebuilt correctly?
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The units field, not the resolution field, is the error. At 300 ppi, 24 in × 36 in equals 7200 px × 10800 px. The 300 px canvas is only 1 in × 1 in at that resolution. Fix: Image > Image Size with Resample off to check pixel dimensions first, but since content already exists at a tiny pixel count, the correct move is a new document at 7200 × 10800 px / 300 ppi with 0.125 in bleed (canvas becomes 24.25 in × 36.25 in, or 7275 × 10875 px). Resolution alone never restores detail - it only relabels pixels.
2. The logo is a Smart Object but the photo is rasterized and enlarged. Explain the practical difference and the correct handling for each.
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A Smart Object stores the source and re-renders on transform, so scaling down and back up is non-destructive; the logo will resample cleanly when the final size is set. A rasterized layer is baked pixels - enlarging 400% interpolates and destroys real detail. Correct handling: keep the logo as a Smart Object and set its final physical size (e.g., 6 in wide at 300 ppi = 1800 px source is ideal; a 400 px source will still be soft, so request vector or a larger original). For the photo, replace it with a higher-resolution original or re-place it as a Smart Object before scaling. If no better source exists, accept it only if it lands at an effective resolution the printer tolerates - 400 px stretched to 24 in is ~17 ppi, which is unusable.
3. The printer asks for a PDF with bleed and crop marks. What export settings matter?
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Use File > Save a Copy to PDF (or Export As), then in the PDF dialog: set Marks and Bleeds > Trim Marks, enable Use Document Bleed Settings (the 0.125 in must exist in Image > Canvas Size or Document Setup), and check Include Bleed. Compression: ZIP or JPEG at Maximum quality for images, and do not downsample below 300 ppi. Confirm the output intent/color profile matches the printer's request (often CMYK or a specified RGB profile), and verify the PDF opens at the correct trim size - a 300 px canvas exported to PDF will be 1 in and reveal the original error immediately.