Pick a container for the next hop. Not for a religion.
Format debates online pretend there is a winner. In a queue, the winner is whatever the next tool will open without wrecking the pixels you still need. Fileliq will encode what you ask. It will not undo a bad choice.
JPEG: photos, scans, tickets
JPEG has no alpha. Flatten happens on PNG→JPG and WebP→JPG. Hard edges ring. Skin and continuous tone survive a sensible quality better than screenshots of UI.
JPG→PNG does not recover detail JPEG already discarded. You pay PNG bytes for the same artifacts. Use that wrap only when a downstream editor refuses JPEG.
JPG→WebP is a second lossy pass. Do not loop it. Compare skin and small type before you delete the JPEG.
PNG: edges, UI, punch-out
PNG is lossless for the pixels it is given. Screenshots, diagrams, and sparse type belong here. Photos as PNG are a tax.
PNG→PDF flattens alpha. If you need punch-out, keep the PNG. PNG→WebP often keeps alpha — verify on a logo before you throw the original away.
PNG→JPG is the flatten-and-shrink hammer. Quality lives on Compress image, not on the straight convert slug.
WebP: bytes, with a decoder tax
WebP is efficient on photos and often on UI. Animation is not preserved on Fileliq’s decode path — still only. If a counterparty cannot open WebP, decode to JPEG or PNG once. Do not mail a support thread about “just install a browser.”
PDF→WebP is a raster for lighter previews, not a master archive. Same sampling limits as PDF→JPG.
A pipeline that does not eat itself
One lossy encode. Then stop. If you must ship two sizes, resize from the original, not from the already-smashed WebP.
Compress image keeps the container and exposes a quality slider (40–95). There is no “visually lossless” promise. Compare input vs output bytes in the queue. Keep the original if the delta is noise.
Resize is a max-width cap. Height follows aspect. No crop, no pad, no square thumb. Upscaling will not invent detail.
- Photo → JPEG or WebP. Inspect. Do not PNG it “for quality.”
- UI / type / alpha → PNG, then maybe WebP if you verified punch-out.
- PDF page stills → JPEG for photos, PNG for diagrams, WebP for internal previews.
- Never: JPEG → WebP → JPEG → PNG. That is generation loss with extra steps.
Steps
- Name the next hop. Editor, CMS, email, CI artifact, or a human who still cannot open WebP.
- Pick the slug. Straight convert for a container change. Compress image if you only need fewer bytes. Resize if you only need a width cap.
- Run once. Queue the original. Inspect. Keep the source until you have looked at edges, alpha, and file size.
FAQ
Which format is smallest?
Usually WebP on photos, JPEG close behind, PNG much larger. Not a law. Measure your file.
Will PNG→JPG keep transparency?
No. JPEG has no alpha. Flattened on purpose.
Can I set JPEG quality on PDF→JPG?
That raster is a straight encode. Quality slider is on Compress image after you have stills.