Mac has a hidden 'Reduce File Size' option in Preview's export menu. It works. It also destroys image quality. Anyone who's used it on a presentation deck and watched the screenshots go fuzzy knows the feeling.
There's a way to compress that keeps quality where you want it.
Preview's compression — and its problem
File → Export → Quartz Filter → Reduce File Size. It's there since macOS 10 and unchanged since. The filter aggressively downsamples all images to ~150 DPI regardless of source quality. For scan archives, fine. For anything with photos or screenshots, the result looks visibly degraded.
Flint's compressor gives you control — Light, Medium, Heavy presets — and uses smarter algorithms that preserve sharpness.
The Flint flow
Open Safari, drag the PDF in, pick compression level, download. Medium usually drops 50–80% of file size with no visible quality loss. Heavy goes further for cases where size matters more than quality (archival, quick email).
Combining with trimming
Compression alone isn't always the answer. If only 10 pages of a 100-page PDF are relevant, split or delete unwanted pages first, then compress the remainder. A trimmed-then-compressed PDF is often 5–10% the size of the original.
FAQ
Why is Preview's compression so aggressive?
It's an old filter that assumes worst-case input (huge images). It applies one fixed setting regardless of source. Modern compressors analyse the document and pick parameters per image. Flint uses modern algorithms; Preview uses 2003-era ones.
Can I create a custom Quartz Filter in Preview?
Yes, via ColorSync Utility. It's powerful but fiddly — most people don't bother. Flint's three presets cover 99% of needs without the setup.
Does compression break OCR text?
No. Compression targets embedded images, not the text layer. Searchable PDFs stay searchable after compression. If a PDF is image-only (no text layer), it stays image-only; compression doesn't add OCR.
Stop watching your PDFs go fuzzy in Preview. Compress with quality control in Flint.