When you need a PDF as an image, two formats are available: JPG and PNG. Most people default to JPG because it is familiar and produces smaller files. But for certain types of PDF content, JPG compression degrades quality in ways that matter, and switching to PNG fixes the problem at the cost of a larger file. Here is how to decide.
The core difference: lossy versus lossless
JPG is lossy. When you save a JPG, a compression algorithm discards some image data to reduce file size. The discarded information is gone, you cannot recover it. For photographic content (faces, landscapes, gradients), the quality loss is typically imperceptible at medium-to-high quality settings. But for content with sharp edges, fine lines, or precise text, the compression artefacts become visible as blurring, haloing, or blocky noise around edges.
PNG is lossless. The compression algorithm in PNG reorganises the image data more efficiently but discards nothing. What you get out is exactly what went in. PNG files are typically 2–4 times larger than their JPG equivalents, but every pixel is exactly as it was in the source.
When PNG gives noticeably better results
PDFs with small text
If your PDF contains body text at normal reading size, 10pt to 12pt, and you need to convert it to an image, JPG compression at typical quality settings will soften the letterforms slightly. At 72 DPI this is obvious. At 150 DPI it is less noticeable but still visible if you zoom in. At 300 DPI it is usually fine even in JPG. However, for screen-resolution exports where text sharpness matters (embedding in a web page, a presentation, or a form screenshot), PNG preserves clean, aliased edges that JPG blurs.
PDFs with logos, line art, or diagrams
Charts, flowcharts, architectural drawings, engineering schematics, and anything with thin lines or hard colour boundaries suffer most from JPG compression. The compression sees a sharp boundary between two colours and introduces a gradient where there should be none. The result looks acceptable at a glance but falls apart when the image is reproduced in print or displayed at high magnification. PNG's lossless encoding keeps those edges exactly as rendered.
Screenshots and UI mockups exported to PDF
If someone has exported a software interface, dashboard screenshot, or design mockup as a PDF, a common workflow when sharing designs for review, and you need it as an image, PNG is almost always the right choice. The content is typically a mix of flat colour blocks, text labels, and pixel-level detail. JPG compression turns flat colour blocks into mottled surfaces. PNG keeps them flat.
PDFs that will be OCR-scanned
Some workflows require converting a PDF to an image, then running OCR on the image to extract text. If the intermediate image format is JPG, compression artefacts around characters can cause OCR errors, particularly for numerals, punctuation, and characters with small features (l, i, 1, |). PNG's lossless output gives OCR engines clean source material and reduces misread characters.
When JPG is perfectly fine
For PDFs that are primarily photographic, scanned documents, photos embedded in a report, image-heavy brochures, JPG at high quality produces files that look identical to PNG on screen and in print, at a significantly smaller file size. Sharing, emailing, or embedding a photo-based PDF page as JPG is entirely reasonable.
JPG is also the right choice when file size is the binding constraint and you can accept minor quality loss. A 4MB PNG and a 0.8MB JPG of the same page may look essentially identical on a phone screen or in a web browser at 100% zoom. If the output will never be printed at large scale or scrutinised at high magnification, JPG is practical and saves storage.
How to convert a PDF to PNG
PDFWhisk's PDF to PNG converter works identically to the JPG converter but outputs PNG files. Open the tool, drop your PDF in, and each page is rendered as a separate PNG image. For multi-page PDFs, all pages are packaged in a ZIP download.
The tool renders at two quality settings:
- Standard (150 DPI), suitable for on-screen viewing, email, and embedding in digital documents.
- High (300 DPI), suitable for print reproduction, large-format display, or situations where the image will be scrutinised at high zoom.
Processing runs in your browser. The PDF is not uploaded to a server, a practical point if the document contains confidential content.
File size: what to expect
PNG file sizes vary considerably depending on content type:
- A text-heavy A4 page at 150 DPI typically produces a PNG between 0.3MB and 1.2MB.
- The same page as JPG at high quality is typically 0.1MB to 0.4MB.
- A photo-based PDF page at 300 DPI as PNG can be 5–15MB; as JPG at high quality, 1–4MB.
If PNG output is larger than you need, the practical alternatives are: lower the output resolution to standard (150 DPI), switch to JPG if content quality allows, or compress the resulting PNG using a lossless PNG optimiser. Compressing a PNG with a lossless tool does not degrade quality, it just reorganises the data more efficiently.
Summary
Choose PNG when: the PDF contains text, diagrams, logos, line art, or flat-colour UI elements, and when sharpness and fidelity matter more than file size. Choose JPG when: the content is photographic, file size is constrained, and you will not be printing at large scale or zooming in closely.
For any PDF containing mixed content, text alongside photographs, PNG is the safer default because it will not introduce artefacts into the text sections, even if the photographic sections end up slightly larger than they would be in JPG.
Use PDFWhisk's PDF to PNG converter to convert in your browser with no upload required. If you are unsure which format to use for a specific document, convert it as PNG once and inspect the output at 100% zoom, you will immediately see whether the sharpness difference is material for your use case.