About this tool
Most "compress this PDF" tools either upload your file to a server or simply repackage the same bytes more efficiently without shrinking anything inside — including this site's own PDF Compress, which intentionally only restructures a PDF's internal storage and never touches image data. This tool is the real, lossy counterpart: it finds every JPEG (and reconstructable PNG) raster image embedded in the PDF, decodes each one with the browser's own image decoder, redraws it onto an in-memory canvas, and re-encodes it as a JPEG at the quality you choose — the exact same Canvas technique this site's standalone Image Compressor tool already uses. Each recompressed image is only kept if it actually came out smaller than the original; if an image was already efficiently compressed, or recompression made it grow (which can happen with very simple or low-color images), the original bytes are kept for that one image instead, so you never trade quality away for nothing.
Because every recompressed image is re-encoded as a JPEG, any transparency an original PNG relied on is lost — recompressed images always end up fully opaque, so this isn't the right tool for a PDF where a transparent logo or watermark needs to stay transparent. Lower quality values shrink files more aggressively but introduce more visible blocky or blurry compression artifacts, so it's worth comparing a couple of settings before settling on one. Everything — decoding, redrawing, and re-encoding every image — runs locally in your browser using the Canvas API; the PDF is never uploaded anywhere. Only the pictures inside the PDF are touched: fonts, vector graphics, and text stay exactly as they were, and encrypted or corrupted PDFs can't be processed.
Frequently asked questions
Will this lose image quality?
Yes, deliberately — unlike our separate structural "PDF Compress" tool, this one performs REAL lossy compression by re-encoding images as JPEG at your chosen quality. Lower quality settings mean smaller files but more visible compression artifacts (blockiness, blurring of fine detail). Always preview or spot-check the result before relying on it for anything where visual fidelity matters, and try a higher quality setting if the result looks degraded.
Will this remove transparency from PNG images?
Yes — every recompressed image, regardless of its original format, is converted to JPEG, which has no alpha/transparency channel at all. If a PNG in your PDF relies on transparency (e.g. a logo meant to blend with the page background), recompressing it will flatten that transparent area to a solid color and it will no longer blend seamlessly. If you have images like that, it's worth reviewing the result closely or skipping recompression for that particular PDF.