DPI (dots per inch) measures scan detail. 72–96 DPI is screen quality – fine to view, not enough for print or for OCR on small text. 200 DPI is the lower bound for reliable OCR. 300 DPI is the standard for most official submissions: tax filings, land registry, government portals, electronic procurement platforms, notarial deeds. 600 DPI and above is reserved for archives, technical drawings, and book digitization.
For every page the tool reports actual resolution of embedded images, pixel dimensions, color space (RGB/CMYK/grayscale), and image count. Within seconds you can tell whether the document meets the agency's requirements, whether it is bloated with 600 DPI images where 200 DPI would suffice, and whether some pages were scanned carelessly – 300 DPI mixed with 96 DPI in the same file is a common issue.
If resolution is below the requirement, rescan the page at the correct setting (scanner drivers usually expose DPI explicitly). If, instead, DPI is excessive and the file weighs tens of megabytes, push it through compression and downscale to a sufficient level. Before submitting to an agency the rule is simple: check the resolution requirement in their regulation, run the PDF through the analyzer, and make sure every page complies.