If you have images to convert to PDF, the format of your source files matters more than most people realise. JPG, PNG, and WebP each compress image data differently, and that affects how they look inside a PDF, how large the output file is, and how long the conversion takes.

JPG: best for photographs

JPEG compression works by discarding visual information the human eye is least sensitive to — high-frequency detail in areas of gradual colour change, like skies, skin tones, and blurred backgrounds. For photographs, this trade-off is excellent: you can reduce file size by 80–95% with almost no perceptible quality loss at default settings. The downside is visible artifacts around hard edges — text, logos, and line art look noticeably worse. For PDF conversion, JPG is ideal when your images are photographs: product shots, portraits, scanned photos, or any image without sharp text or geometric shapes.

PNG: best for documents and graphics

PNG uses lossless compression — every pixel in the output is identical to the input. This makes PNG the obvious choice for screenshots, diagrams, charts, presentation slides, UI mockups, and any image with sharp text. There are no artifacts and no colour degradation. The trade-off is file size: a PNG screenshot of a text document may be 3–10 times larger than the equivalent JPEG. For PDF conversion, PNG is the right choice whenever text sharpness, line art accuracy, or logo fidelity is important.

WebP: best for web images that need archiving

WebP was developed by Google to replace both JPEG and PNG for web delivery. It offers both lossy and lossless modes, typically achieving files 25–35% smaller than equivalent JPEG at the same visual quality. For PDF conversion, WebP behaves similarly to JPEG — it is re-encoded through the browser's canvas, so the WebP compression advantages do not carry through directly. It is a good source format when you have downloaded images from modern websites that use WebP by default.

GIF: handle with care

GIF is a legacy format limited to 256 colours and without the compression efficiency of modern formats. For static images, GIF is largely obsolete — PNG produces smaller files at higher quality. The main use case for GIF-to-PDF conversion is capturing still frames from animated GIFs, where only the first frame is extracted.

Quick reference

Use JPG for photos and scanned images. Use PNG for screenshots, text-heavy images, logos, and diagrams. Use WebP for images downloaded from modern websites. If you are unsure, PNG is always the safe default — it preserves exactly what you see with no quality loss.