Reduce image quality in a PDF
Target only the embedded images in a PDF to reduce their quality and size, without touching the text or layout — useful when a document is mostly made up of heavy photos or scans.
How it works
The tool first detects the images embedded in the PDF to tell you how many it contains, then re-encodes each of them at the chosen quality (JPEG compression that is more or less aggressive depending on the preset). The document's text and vector elements are never modified: only the image quality changes.
Why can the number of detected images be zero on a heavy document?
Some images are referenced from resources inherited from the document structure rather than directly from each page, or are nested inside a "Form" object — rare cases that this detection doesn't pick up. The file's size may still come from other elements (embedded fonts, complex vector content).
Which quality should I choose if I don't know which one fits?
"Low (balanced)" is a good starting point for most documents: it clearly reduces the size without visible degradation on screen or in standard printing. Reserve "Very low" for cases where file size is your absolute priority, and "Minimal" for when image fidelity matters more than the size savings.
100% local processing in your browser (WebAssembly) — your PDF is never sent to a server.