| 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/ |
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)