Add support for color profiles

[sophie-h]

Hey,

we are planning to use libheif-rs for GNOME's new image view Loupe. However, we need access to the color profiles. That would, especially the get_color_profile_type, color_profile_nclx, raw_color_profile functions. Can you make them available in the bindings or accept PRs?

[Cykooz]

Yes, I will make these functions.

[Cykooz]

@sophie-h Could you get me example of heic/heif image file with NCLX color profile for testing?

[sophie-h]

Yes, here is a .avif and .heif exported HDR (nCLX) image I have created with Krita for my testing.

https://gitlab.gnome.org/Incubator/loupe/uploads/322f81512346f3fd69b0acc502c04201/test.zip

[Cykooz]

I have released libheif-rs 0.16.0

Example of receiving color profile:

libheif-rs/tests/read_test.rs

Lines 255 to 286 in bb90749

	fn test_nclx_color_profile_of_image_handle() -> Result<()> {
	let ctx = HeifContext::read_from_file("./data/test_nclx.heif")?;
	let handle = ctx.primary_image_handle()?;
	let raw_profile = handle.color_profile_raw();
	assert!(raw_profile.is_none());
	let nclx_profile = handle.color_profile_nclx().unwrap();
	assert_eq!(nclx_profile.profile_type(), color_profile_types::NCLX);
	assert_eq!(
	nclx_profile.color_primaries(),
	ColorPrimaries::ITU_R_BT_2020_2_and_2100_0
	);
	assert_eq!(
	nclx_profile.transfer_characteristics(),
	TransferCharacteristics::ITU_R_BT_2100_0_PQ
	);
	assert_eq!(
	nclx_profile.matrix_coefficients(),
	MatrixCoefficients::RGB_GBR
	);
	assert_eq!(nclx_profile.full_range_flag(), 1);
	assert_eq!(nclx_profile.color_primary_red_x(), 0.708);
	assert_eq!(nclx_profile.color_primary_red_y(), 0.292);
	assert_eq!(nclx_profile.color_primary_green_x(), 0.17);
	assert_eq!(nclx_profile.color_primary_green_y(), 0.797);
	assert_eq!(nclx_profile.color_primary_blue_x(), 0.131);
	assert_eq!(nclx_profile.color_primary_blue_y(), 0.046);
	assert_eq!(nclx_profile.color_primary_white_x(), 0.3127);
	assert_eq!(nclx_profile.color_primary_white_y(), 0.329);
	Ok(())
	}

[sophie-h]

Hey! This is working great!

I have found some minor problems during implementation:

• Having heif_image_get_bits_per_pixel_range available for the channels would be handy.
• The bits_pre_pixel field probably has a typo? (pre -> per)
• Planes and Plane are not documented. Probably because they are not exported as types in lib.rs and the image module is not public

[Cykooz]

Thank you.
Look at the new release libheif-rs 0.17.0

[sophie-h]

Very cool. I think I got everything working now :)