JPEG 2000 support via the hayro-jpeg2000

[bowenxuuu]

follow up #751

fix #730

[bowenxuuu]

decode by openjpeg-sys

decode by hayro-jpeg2000

@LaurenzV
The colors decoded by hayro-jpeg2000 appear incorrect, but I haven't yet figured out the root cause.

[bowenxuuu]

https://github.com/LaurenzV/hayro/blob/20888608e8682f57a23632924fd87d2858fca359/hayro-jpeg2000/src/lib.rs#L550-L551

After I changed T::from_scaled_f32() to T::from_native_f32(), everything works as expected.

This image decode by T::from_native_f32() of hayro-jpeg2000.

[LaurenzV]

Is this image available somewhere so I can try it myself?

[bowenxuuu]

Here's the DICOM image.

img.zip

[LaurenzV]

Okay, so I get it now. The method I added always scales to 16-bit, but what you want is something that always preserves the native bit depth. I think it's best if I instead expose an API for the raw f32 samples, then this should be the same as you are currently doing.

[LaurenzV]

Could you try this one instead? LaurenzV/hayro#1243

I think the code should then look something like this:

#[cfg(feature = "hayro-jpeg2000")]
{
    use hayro_jpeg2000::{DecodeSettings, DecoderContext, Image};

    let image = Image::new(&frame_data, &DecodeSettings::default())
        .whatever_context("hayro-jpeg2000 read image failure")?;

    let mut ctx = DecoderContext::default();
    let decoded = image
        .decode(&mut ctx)
        .whatever_context("hayro-jpeg2000 decoder failure")?;

    let components = decoded.components();

    for (component_i, component) in components.iter().enumerate() {
        if component_i >= samples_per_pixel as usize {
            warn!(
                "JPEG 2000 image has more components than expected ({} >= {})",
                component_i, samples_per_pixel
            );
            break;
        }

        for (i, sample) in component.samples().iter().enumerate() {
            let offset = base_offset
                + i * samples_per_pixel as usize * bytes_per_sample as usize
                + component_i * bytes_per_sample as usize;

            let sample = sample.round() as u32;
            dst[offset..offset + bytes_per_sample as usize]
                .copy_from_slice(&sample.to_le_bytes()[..bytes_per_sample as usize]);
        }
    }
}

[bowenxuuu]

@LaurenzV Thanks, it works well now.

[LaurenzV]

Should be included in version 0.4.0 now. :)

[bowenxuuu]

@Enet4 Hello