Convert TIFF to AVIF — Free, Fast & Private
If you are converting scans or print masters and the colour matters, AVIF is the destination worth knowing about. Every other web format — JPEG, PNG as commonly written, WebP — stores 8 bits per channel. AVIF handles 10 and 12 bits, which is the range professional scanners and cameras actually capture into a TIFF.
That makes this the least destructive way to get a high-bit-depth TIFF onto the web, and by a wide margin the most space-efficient.
Why bit depth is the interesting part
A 16-bit-per-channel TIFF holds 65,536 levels per channel. Squeezed into 8 bits, that becomes 256. On most finished images nobody can tell, because a screen shows 8 bits regardless.
Where it shows is in wide, gentle gradients — the sky in a landscape scan, a studio backdrop, the paper tone across a large document scan. With only 256 steps to describe a slow transition, the steps become visible as faint bands. Keeping 10 bits gives 1,024 steps and the gradient stays smooth. Archival scanning is one of the few everyday cases where this genuinely matters, because scanners are precisely the devices that capture more depth than a screen needs.
What still changes, exactly as with any TIFF conversion
Multi-page TIFFs give you one page. Document scanners routinely put a whole contract into a single .tif; AVIF holds one still image. Convert multi-page documents to PDF instead.
CMYK becomes RGB. Print-workflow TIFFs carry four ink channels, often with a press-specific profile. AVIF is RGB, so a colour-space conversion happens and saturated cyans, deep blues and rich blacks may shift. Keep the CMYK TIFF as your print master; the AVIF is a screen derivative.
The alpha channel survives. Where a TIFF carries transparency, AVIF preserves it with a full 8-bit alpha channel.
Size, speed and the practical trade
A 300 DPI A4 scan as TIFF is often 25 MB or more, because TIFF is uncompressed or losslessly compressed. As AVIF the same page commonly lands under 200 KB — reductions above 98% are ordinary for photographic scans.
The cost is time. AV1-derived encoding is heavy, and a batch of large scans takes appreciably longer than the same batch to WebP. It runs off the main thread so the interface stays responsive, but a hundred 25 MB scans is not an instant job. If throughput matters more than the last few percent, TIFF to WebP is considerably faster.
Do not treat AVIF as your archive format
Worth saying plainly, because the size figures are seductive: AVIF at normal settings is lossy, and TIFF is your master. Keep the TIFFs. Use AVIF for delivery — the web copy, the catalogue thumbnail, the version you send to someone — and retain the originals for anything that has to be re-edited, re-printed or held as a record of what was scanned.
AVIF is encoded on your device, so the option appears only when your browser has a working encoder; MiniPx probes for one and validates the output header rather than handing you a PNG in disguise. Nothing is uploaded, which is the relevant point when the scans are records or client documents. For lossless output, use TIFF to PNG.