Resolution: PPI at the Placed Size
Raster image quality depends on pixel dimensions at the size used in the PDF. A “300 DPI” label alone does not prove that the placed image contains enough detail.
Raster image quality depends on pixel dimensions at the size used in the PDF. A “300 DPI” label alone does not prove that the placed image contains enough detail.
PPI and DPI
PPI is image pixels per inch at the placed size. DPI is output-device dots per inch. A screen does not universally require 72 PPI, and a press does not universally require every image to be 300 PPI.
For a 1200-pixel-wide image:
| Placed width | Effective horizontal resolution |
|---|---|
| 4 inches | 300 PPI |
| 8 inches | 150 PPI |
The print provider determines the target according to screening, viewing distance, artwork and process. Fine line art, photographs and distant large-format graphics may need different targets.
Read a resolution finding
Run preflight and read the selected rule, affected object/page and measured effective resolution. A warning is tied to that rule; this page does not define a universal automatic rejection below 150 or 300 PPI. If geometry or image data cannot be measured, keep the result unknown.
Safe suggestions and re-upload
Correct the design source, export and upload a new PDF version, then rerun the relevant check. The previous report is not evidence for the new file.
Use the original high-resolution source when possible. Changing metadata without adding pixels leaves effective detail unchanged. Resampling or an image-upscale step can change pixels and appearance, but does not prove recovery of the original detail. Review its explicit settings and output.
Vector paths and text do not have the same raster PPI limit, but a PDF or EPS can also contain raster images, masks and effects. The file extension does not promise unlimited quality. See basics and reading results.
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