Notes from the team on craft, formats, and the small decisions behind a good round crop.
Why AVIF input is quick but AVIF output drags
There is a common assumption that AVIF is slow from start to finish, and it gets the decode wrong. Reading AVIF in is fast. Its native decoders sit in Chrome from 85, Firefox from 93, and Safari from 16.4, every one compiled native code carrying no JavaScript tax, so a 1024 by 768 AVIF comes apart in tens of milliseconds. Writing AVIF is the slow half. AV1 compression sifts many prediction modes per block and toils through expensive rate-distortion passes. On the JPG to AVIF page, where this site writes AVIF, a heavy software encoder does that toiling. Here, where it only reads AVIF, the fast native decoder runs, with no module to fetch, no warm-up, and no init costing several hundred milliseconds. That divide is why AVIF to JPG feels quick where JPG to AVIF stretches into seconds.
The transparency snag up close: alpha, compositing, and white fill
Opacity per pixel, from 0 fully clear to 255 fully solid, is what AVIF's alpha channel stores. Once the browser paints that AVIF onto a working surface and then encodes the surface as JPEG, the compositing step has to decide each pixel's final colour. By default the surface opens as transparent black, R 0 G 0 B 0 A 0. The JPEG output path then washes the surface background white before encoding, since JPEG holds no alpha and is obliged to return something solid. So every clear region of your AVIF arrives white in the JPG. A part-clear pixel composites onto white, which leaves one at 50 percent opacity sitting halfway between its own colour and white. Nothing short of painting the compositing yourself onto a surface with a custom background changes that fill, and that is editor territory, not converter territory.
Quality measured: what 43.66 dB PSNR means in use
Read in decibels, PSNR, the Peak Signal-to-Noise Ratio, tells how closely a re-encode follows its source, with a higher number the better. The JPEG writer here logged 43.66 dB PSNR in our end-to-end run, measured on a standard 1024 by 768 photographic fixture at standard quality. Some scale helps: roughly 36 dB marks the line below which differences turn plainly visible to most people in normal conditions, while 40 dB is generally counted perceptually transparent for photographic content. At 43.66 dB the output reads as the source for photos shown on screens at typical sizes. Graphics with crisp edges, fine type, or harsh contrast may still flash faint JPEG marks, because JPEG's block-based DCT handles those areas unlike the smooth gradients of a photograph.
AVIF compatibility: where it lands and where it still trips
As of mid-2026, AVIF decodes in all major browsers, yet compatibility with non-browser software is still spotty. On Windows, the AVIF Image Extension from the Microsoft Store adds support to Photos and File Explorer on Windows 10 and 11, and without it AVIF files show as blank icons. Adobe added AVIF support in Lightroom 13.3 in 2024 and Photoshop 23.2 in 2022, so earlier builds cannot open it. Affinity Photo 2.3 from 2023 handles AVIF import and export. Paint.net needs the free AVIF plugin. On macOS, Preview has read AVIF since Monterey. On phones, the system photo viewer takes AVIF on iOS 16 and Android 12 and later. The gaps are real and clustered in enterprise tools, upload boxes, and print chains, which are exactly the spots where converting to JPG is the practical fix.
AVIF against HEIF: the split and why it counts
Modern video codec compression sits under both AVIF and HEIF, the High Efficiency Image File Format. HEIF generally rides HEVC, also tagged H.265, while AVIF rides AV1. For the web the deciding split is licensing. HEVC bills per-device royalties that browser makers would rather not cover, which is why Safari takes HEIF and Chrome does not. AV1 was made royalty-free on purpose, by an industry alliance whose members include Google, Mozilla, and Apple. That is what hands AVIF broader browser support than HEIF even though HEIF came first. Since the iPhone 7, iPhones have shot photos as HEIF, those files ending .heic. Converting HEIC to JPG is a different tool category from AVIF to JPG. This one reads AVIF input only, so a .heic file off an iPhone belongs in the HEIC to JPG converter instead.
When to hold AVIF and when to make a JPG
One guideline carries most cases: hold onto AVIF for as long as both ends of the workflow are yours, and switch to a JPG the moment a file has to enter territory you do not govern. Picture images you deliver from a site you built, fronted by a CDN that negotiates format. There AVIF takes the prize, lighter on the wire, indistinguishable on screen, and now spanning 94 percent of browser traffic. Now picture the file bound elsewhere, into a mailed newsletter, a post uploaded to social, a submitted web form, a print template a client handed over, a shared Dropbox folder colleagues open on dated software, or a legacy CMS fussy about MIME types. In all of those, JPG is the calmer bet. So the habit most web teams fall into is archiving the AVIF originals and generating JPG exports on request wherever a file just has to open anywhere.
