[Wowfunhappy]

> Max image size is limited to 4K (3840x2160) in AVIF

What?! That is terrible for a next-generation image format, and should be an immediate and obvious dealbreaker for introducing any type of support.

It would be one thing if AVIF was a legacy format already in widespread, but anything new should be several orders of magnitude more future-proof.

[izacus]

Maximum image size for AVIF is 65535x65535, no idea where you're all picking up this crock.

[formerly_proven]

Seems to be not so simple.

> AVIF has different limitations when it comes to the highest megapixel count / largest dimensions. Several decoders may not support larger images, so single-coded photos do not exceed 4k resolution. According to AV1, AVIF Baseline profile coded image items must not have more pixels than 8912896 or wider widths or higher heights than 8192 or 4352. The Baseline profile can still be used to create larger images using grid derivation. You might encounter discontinuities along the grid boundaries, depending on how the image is decomposed. For this particular case, however, the maximum size of a coded picture is 65536x65536.

https://avif.io/blog/faq/avif-megapixel/

So as I understand this, anything with more than ~9 MP would be encoded in some kind of tiled way, possibly introducing artifacts where tiles meet.

However, another blog post claims different limits

> The default limit of AVIF is 8K. Video professionals will recognize this as the size of an 8K video frame. It is possible to break this limit for both formats by independently encoded tiles of 8K frames. But this method introduces artifacts at the tile boundaries, affecting the overall appearance of images.

https://avif.io/blog/comparisons/avif-vs-heif/

[brigade]

The profiles only matter if you want to be decodable by hardware decoders. If you only care about software decoders, which must be true if JPEG-XL is your comparison, then you don't have to use the HEIF grid for large dimensions, and the better question is how much memory your application will allow to be allocated. Because chances are JPEG's maximum 65535x65535 exceeds it that too.

AV1 itself allows a maximum of 65536x65536 for a single picture, whereas the HEIF grid hypothetically allows even more than that regardless of how large each individual picture is (HEIF grid dimensions are 32-bits). As a practical example, libavif will not use the grid for large dimensions unless explicitly told to do so, by default producing files that aren't compliant to either baseline or advanced profiles.

(to further my pedantry against your source: AVIF is a subset of HEIF; what people usually mean by "HEIF" is the HEIC subset)

[izacus]

It is that simple, you're just noving the goal posts.

The concept of profiles is nothing new to ensure HW decoder compatibility and JPEG-XL offers nothing extra there either (except no support for the concept ensuring that HW decode isn't possible at all).

Pretty much all newer formats are tiled in some way too - even JPEG.

[pixelesque]

The format supports that technically (the resolution is stored in two uint32_t variables), but libavif however currently seems to have pretty small limits in this area based off attempts a few months ago to try using it for high res photos: I couldn't get it to save images of size 8192 x 5464 (native Canon R5 res). avifEncoderAddImage() just returns a generic error when the size is too big. If I reduced the size of the image a bit, it then worked.

Given I was trying to store high res panoramas of even larger dimensions, I was pretty surprised at the apparent limits, wherever they exist in the callstack.