Converting a PDF to PNG produces a lossless image of each page. Unlike JPEG, PNG does not introduce compression artifacts — every pixel in the output is an exact representation of what was in the PDF. For documents with sharp text, technical diagrams, or precise line art, PNG is the correct choice.
PNG vs JPEG for PDF pages
JPEG uses lossy compression that reduces file size by discarding visual information. The discarded information appears as ringing artifacts around high-contrast edges (text on a white background, line drawings, logos). For photographs this trade-off is often acceptable; for documents it is not.
PNG uses lossless compression. No information is discarded: the output is a bit-for-bit representation of each pixel. The file size is larger than an equivalent JPEG, but quality is perfect. For screen captures, technical documentation, slide decks, and any document where text legibility matters, PNG is the right format.
Resolution
Filum renders PDF pages at 300 DPI — the standard resolution for print-quality output and clear legibility at any zoom level. A standard A4 page (8.27 × 11.69 inches) produces a 2480 × 3508 pixel PNG at 300 DPI. This is the same resolution used by professional document scanners and sufficient for most use cases.
Multi-page PDFs
Each page of the PDF becomes a separate PNG file. For a single-page PDF you receive one PNG; for a multi-page PDF, each page is numbered and the set is delivered as a ZIP archive. The ZIP preserves the page order and makes downloading all pages in one click straightforward.
PNG vs JPG for PDF pages
PNG is a lossless format: every pixel in the output image is exact. JPG uses lossy compression that discards visual information to achieve smaller file sizes, which is acceptable for photographs but introduces artefacts on text, diagrams, and line art. For PDF pages containing text, charts, or line drawings, PNG produces a noticeably sharper result than JPG at equivalent file size settings.
JPG is the better choice when file size is the priority and the content is photographic. PNG is the better choice when sharpness, accuracy, and archival quality matter more than file size.
Output DPI
The PDF to PNG tool renders pages at 300 DPI using pdf.js. At 300 DPI, an A4 page (210x297mm) produces a PNG that is 2480x3508 pixels. This is the resolution standard for print-quality output and is sharp enough to remain legible even when zoomed to 200%.
Multi-page PDFs
When a PDF contains multiple pages, each page is rendered as a separate PNG and all images are packaged into a ZIP file for download. The file names follow a numbered sequence (page-1.png, page-2.png, etc.) so the order is preserved.