Convert AVIF to PNG

The two reasons to do this

There are only two good reasons to turn an AVIF into a PNG. The first is opening it: plenty of software still cannot display AVIF, and a file you cannot look at is not much use. The second is editing: AVIF is lossy, so every save discards more, and a PNG master means a sequence of edits does not degrade the image. Anything else, such as wanting a smaller file, is moving in the wrong direction.

MDN: image file type and format guide

What is preserved and what is reduced

PNG will keep the pixel data exactly as AVIF holds it, so the visible image is preserved perfectly. Two AVIF characteristics do not survive the trip to a typical PNG. Smooth partial transparency becomes binary transparency, so a soft edge in an AVIF logo will gain a harder edge, which is rarely noticeable. And a 10-bit AVIF becomes 8-bit in a standard PNG, so a very subtle gradient can band slightly. Both are small losses, and both are smaller than the alternative of not being able to open the file at all.

• Pixel data is preserved exactly as the AVIF held it.
• Smooth alpha becomes binary, so soft edges harden slightly.
• A 10-bit source becomes 8-bit, which can band a very subtle gradient.
• Use a 16-bit PNG if the gradient banding is unacceptable.

The file size, stated plainly

A PNG will typically be several times larger than the AVIF it came from, and for a high resolution photograph that can mean tens of megabytes. That is the cost of lossless storage, and it is a real cost rather than a rounding error. If the goal is a small file, this conversion is exactly backwards. If the goal is a master you can edit repeatedly, the size is justified and you would compress at the end rather than at the start.

• Expect a PNG to be several times the size of the source AVIF.
• A high resolution photograph can reach tens of megabytes as PNG.
• If you want a small file, keep the AVIF or use WebP instead.
• If you want an editable master, the size is the price and the correct trade.

NoteStore the PNG as a working master and export a small delivery file from it at the end.

A sensible working pattern

The pattern that makes this efficient is to keep the AVIF as the delivery file and the PNG as the working master, converting once in each direction from the appropriate source. Editing happens on the PNG, delivery uses the AVIF, and neither goes through repeated lossy steps. That is the same principle as keeping a RAW alongside a JPG, applied to a modern format pair, and it is what prevents the slow degradation that repeated conversion causes.

• Keep the AVIF for delivery and the PNG for editing.
• Convert from the original each time rather than chaining formats.
• Export a small file from the PNG when the edit is finished.
• Do not re-encode the delivery file repeatedly to make it smaller.