# Options

pillow_heif.options.DECODE_THREADS = 4

  Maximum number of threads to use for decoding images(when it is possible)

  When use pillow_heif as a plugin you can set it with: register_*_opener(decode_threads=8)

pillow_heif.options.THUMBNAILS = True

  Option to enable/disable thumbnail support

  When use pillow_heif as a plugin you can set it with: register_*_opener(thumbnails=False)

pillow_heif.options.DEPTH_IMAGES = True

  Option to enable/disable depth image support

  When use pillow_heif as a plugin you can set it with: register_*_opener(depth_images=False)

pillow_heif.options.QUALITY = None

  Default encoding quality

  Note

  Quality specified during calling `save` has higher priority then this.

  Possible values: None, -1, range(0-100). Set -1 for lossless quality or from 0 to 100, where 0 is lowest and 100 is highest.

  Note

  Also for lossless encoding you should specify `chroma=444` during save.

  When use pillow_heif as a plugin you can set it with: register_*_opener(quality=-1)

pillow_heif.options.SAVE_HDR_TO_12_BIT = False

  Should 16 bit images be saved to 12 bit instead of 10 bit``

  When use pillow_heif as a plugin you can set it with: register_*_opener(save_to_12bit=True)

pillow_heif.options.SAVE_NCLX_PROFILE = True

  Should be `nclx` profile saved or not.

  Default for all previous versions(pillow_heif<0.14.0) was NOT TO save nclx profile, due to an old bug in Apple software refusing to open images with nclx profiles. Apple has already fixed this and there is no longer a need to not save the default profile.

  Note

  save_nclx_profile specified during calling `save` has higher priority than this.

  When use pillow_heif as a plugin you can unset it with: register_*_opener(save_nclx_profile=False)

pillow_heif.options.PREFERRED_ENCODER = {'AVIF': '', 'HEIF': ''}

  Use the specified encoder for format.

  You can get the available encoders IDs using `libheif_info()` function.

  When use pillow_heif as a plugin you can set this option with `preferred_encoder` key.

pillow_heif.options.PREFERRED_DECODER = {'AVIF': '', 'HEIF': ''}

  Use the specified decoder for format.

  You can get the available decoders IDs using `libheif_info()` function.

  When use pillow_heif as a plugin you can set this option with `preferred_decoder` key.

pillow_heif.options.GRID_TILE_SIZE = 0

  Default tile size for grid encoding.

  When set to a positive value, images larger than this size in at least one dimension will be split into a grid of tiles during encoding. This matches how Apple devices encode HEIF photos and can improve compression efficiency.

  Common values: 512 (Apple default), 256, 1024. A value of 0 (default) disables grid encoding. A grid cannot have more than 256 rows or columns and a file cannot have more than 1000 items in total: tiles, thumbnails and metadata blocks all count. Readers with default libheif security limits cannot open files with more items.

  Images with an alpha channel are always encoded as a single image: libheif stores alpha only on the individual tiles, where readers like Apple’s ImageIO ignore it and render the image fully opaque. `AVIF` images are also encoded as a single image when the grid would violate MIAF constraints that `libavif`-based readers enforce: a tile size smaller than 64, or an odd width, height or tile size together with subsampled chroma. Saving an image in `YCbCr` mode with grid encoding enabled raises `ValueError`.

  When use pillow_heif as a plugin you can set it with: register_*_opener(grid_tile_size=512)

  Note

  For images that were read from a tiled HEIF file, the source tile size is used by default during saving, except for images converted to `YCbCr` mode. `tile_size` specified during calling `save` has higher priority.

## Example of use

    import pillow_heif

    pillow_heif.options.THUMBNAILS = False
    pillow_heif.options.DECODE_THREADS = 1

## Overriding multiple options at once

When registering a Pillow plugin with `pillow_heif.register_heif_opener()`

    register_heif_opener(thumbnails=False, quality=100, decode_threads=10)