Output file image has artifacts

[Msey]

To convert heic image to number of png frames or just one jpg file i'm using examples from your main page like this one:

using (var fs = new FileStream("filename.heic", FileMode.Open))
{
    HeicImage image = HeicImage.Load(fs);
     
    var pixels = image.GetByteArray(Heic.Decoder.PixelFormat.Bgra32);
    var width = (int)image.Width;
    var height = (int)image.Height;
     
    var wbitmap = new WriteableBitmap(width, height, 72, 72, PixelFormats.Bgra32, null);
    var rect = new Int32Rect(0, 0, width, height);
    wbitmap.WritePixels(rect, pixels, 4 * width, 0);
    
    using FileStream saveStream = new FileStream("output.jpg", FileMode.OpenOrCreate);
    JpegBitmapEncoder encoder = new JpegBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(wbitmap));
    encoder.Save(saveStream);
}

But the output image is tiled with strange squares

What the cause of it and how to solve the problem?

[Horodep]

@Msey this looks like the miscalculations in cabac context variables. It's library issue, not the incorrent usage. Can you provide the original file for the futher research?

If you are interested in details, the image inside is represented as multiple 512*512 images, and each block is decoded separately. As a result even if there are miscalculations during decoding, the next square will start decoding with correct colors. This brings us this tile view.

[Msey]

@Horodep
image3.zip
Sure. Here's the archive with mentioned image

[Horodep]

@Msey
We'll research it and fix in the next versions.
We'll try to deliver this patch in Q1 2025, but there no real ETA untill the proper research is done.
Thank you for your patience!

[Horodep]

@Msey
We have researched the file and implemented the fix. It will be delivered with new version in the near future.
Are you the author of the photo?
If yes, can we add it to the repository and use it in testing?

[Msey]

@Horodep No. I'm not the author

Tnx for the fix

[Horodep]

Fixed in 915fe0c. Thank you for the feedback.