Support new color modes in libheif 1.6.2

[damonlynch]

When opening a Canon HEIF file supported by libheif 1.6.2:

  i = pyheif.read_heif(image_path)
  File "/home/damon/.local/lib/python3.6/site-packages/pyheif/reader.py", line 29, in read_heif
    result = _read_heif_bytes(d, apply_transformations)
  File "/home/damon/.local/lib/python3.6/site-packages/pyheif/reader.py", line 36, in _read_heif_bytes
    result = _read_heif_context(ctx, d, apply_transformations)
  File "/home/damon/.local/lib/python3.6/site-packages/pyheif/reader.py", line 56, in _read_heif_context
    result = _read_heif_handle(handle, apply_transformations)
  File "/home/damon/.local/lib/python3.6/site-packages/pyheif/reader.py", line 78, in _read_heif_handle
    raise HeifError(code=error.code, subcode=error.subcode, message=ffi.string(error.message).decode())
pyheif.error.HeifError: Code: 4, Subcode: 3003, Message: "Unsupported feature: Unsupported color conversion"

Let me know if you need a sample HEIF file from a Canon 1D X Mark III. (I don't own the camera, but someone who does created some for me.) They are 10 bit images.

[ghost]

Thanks, if you provide a sample I'll check it out.

[damonlynch]

Hi David,

if you could please email me using the address at https://damonlynch.net/ I'll send you a dropbox link to some samples (which I'd like to keep private, thanks).

Sorry for the delayed reply — computer hardware problems today.

Thanks,
Damon

[damonlynch]

Attached is a sample script.

heif.zip

[ghost]

This is complicated. libheif does seem to decode 10-bit (non-rotated) HIF files from the Canon 1D X Mark III, but I haven't found a way to load the resulting data into a viewer to determine if they've been decoded correctly. Pillow, which I normally use to validate decoding, only supports 8-bit images.

It might be best to wait for libheif to support transforms in 10-bit files, and then see what they do for JPEG thumbnail previews - e.g. how do they convert to 8-bit?

[damonlynch]

My sample script had a bug (cannot display a pixbuf when it's data is not in memory). Attached is a working version.

Yes it might be best to wait to see what the libheif folks do. I suspect in future pillow, Gtk and Qt will provide native 10 bit image support.
heif.zip

[ghost]

I've added support for the convert_hdr_to_8bit decoding option added to libheif 1.7 and enabled it by default, should just work now. I'll cut a new release soon.

[damonlynch]

Thanks David!

[ghost]

Also if you can manage a sample image that I can put into the tests that would be great. I want something I can check-in and run regressions on - can't find anything on the web for some reason.

[damonlynch]

I can share a vertical and a horizontal image the owner of a Canon 1DX Mark III shared with me. They're large files. What is the best way to share it with you?

[ghost]

Can you make a pull request? If so pls put them into tests/images/. Thanks!

[damonlynch]

I'd prefer another method. Figuring out how to do that is not something I can do right now, sorry. (I have an extremely serious academic deadline to deal with.) If you can suggest an alternative method I'd be grateful.