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File Formats: AVIF

The AV1 Image Format is an open, royalty-free file format created by Alliance for Open Media to provide superior lossless and lossy compression for images on the web. The format supports still image and sequences (video). LEADTOOLS currently supports only the still image version of the format.

Note

This format should not be confused with the AVI file format used for video. The '1' after AV is the digit one, not the 'i' capital letter. In other words, this should not be confused with popular AVI (Audio Video Interleave) format containing audio and video files. The names are similar, but AVIF files are completely different from AVI files.

The format is supported by multiple browsers and operating systems. Please see the AV1 wikipedia page for more information.

The format uses 24 or 32-bits/pixel (color) or 8-bit (grayscale). The 32-bit file uses alpha channel transparency, where pixels can range from fully transparent to fully opaque.

The lossy single page format is intended to replace JPEG. The lossless single page is intended to replace PNG and GIF.

Compression

The AVIF format uses AV1 compression (lossy or lossless) and stores the images in a ISO Base File Format container (HEIF). There are many similarities with the HEIC format, which also stores images in a HEIF container (but with a HEVC video compression). This is why both AVIF and HEIC file formats are supported by the LFHEIF filter.

The AVIF files use the extension .avif.

Features

Alpha channel/transparency information. The 32-bit file contains a transparency channel. For these files, alpha of 0 represents transparent pixels, 255 represents opaque pixels, and alpha of 1-254 values represent translucent pixels.
Exif metadata, which can contain the comments and tags supported by TIFF and EXIF. AVIF files can contain an embedded TIF file that contains only tags and comments information (no image data). Consequently, any metadata that can be saved in TIFF/Exif files can be saved in AVIF as well.
- Use the L_ReadFileComment or L_ReadFileComments function to read comments from an existing file. Before writing a file, use the L_SetComment function to create an array of comments to be saved in the file. See the Exif File Comments for the list of comments supported.
- Use L_ReadFileTag2 to read TIFF/Exif tags from an existing AVIF file. Use L_SetTag before calling the save function to add your own custom tags to the output file.
- The functions listed above are the most common functions for working with Exif metadata. Refer to Implementing TIFF Comments and Tags for more details.
Lossy/Lossless compression. Save lossy files by setting qFactor between 1 (highest quality, lowest compression) to 63 (lowest quality, highest compression). Use a qFactor of 0 to save lossless files.
Thumbnails (Stamps). Use L_ReadFileStamp2 to read a thumbnail. You can save a stamp by setting the ESO_SAVEWITHSTAMP flag in the SAVEFILEOPTION.Flags structure member prior and setting the stamp width, height and bits per pixel to calling the save function.
8-bit, 10-bit and 12-bit components. AVIF files will typically have 3 x 8-bit color components, which means they are loaded and saved as 24-bit. But the format also supports 10-bit and 12-bit components, and these files are loaded as 48-bit by default. Color images with alpha channel will be loaded as 32-bit (8-bit components) or 64-bit (10/12-bit components) by default. Grayscale images with 10/12-bit components are loaded by default as 16-bit grayscale. LEADTOOLS will save only 8-bit components (24/32-bit for color or 8-bit grayscale).
Rotate/Flip/Reverse transformation. You can perform a lossless rotate/flip/reverse transformation of an existing file using L_TransformFile, the same way as for CMP, JPEG and TIFF images.