Image flipped when converting TIFF to PNG

[bjornhellander]

Magick.NET version

14.11.1

Environment (Operating system, version and so on)

Windows 11

Description

I am working with a product that needs to convert TIFF files to an more browser supported image format. We have chosen PNG for now. Some images, typically originating from mobile phones, are unfortunately not converted correctly.

I have attached one example TIFF file, which to the best of my understanding is "natively" rotated 180 degrees (= I would have to tilt my head 180 degrees to be able to read the text in the image), but there are EXIF data etc which instead makes the image being presented as rotated 90 degrees counter clockwise.

After conversion to PNG format, the image is rotated the expected way (90 degrees), but also flipped vertically, which I did not expect. Not sure at all if this is a bug or if I am missing something in the code. The included code is a simplification of the real code, but includes the relevant parts.

I have tried to convert to JPG instead, but no change.

This specific example image is a single frame TIFF. I have also tried to load it directly as an MagickImage instead of a collection, but I get the same behavior.

Any help would be appreciated in getting this converted correctly!

Steps to Reproduce

using System.Reflection;
using ImageMagick;

var binPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)!;
var sourceFilePath = Path.Combine(binPath, "Example.tiff");

using var sourceCollection = new MagickImageCollection(sourceFilePath);

foreach (var image in sourceCollection) {
    image.AutoOrient();
}

using var targetCollection = new MagickImageCollection();
for (var i = 0; i < sourceCollection.Count; i++) {
    targetCollection.Add(sourceCollection[i]);
}

using var targetImage = targetCollection.AppendVertically();
var imageContent = targetImage.ToByteArray(MagickFormat.Png);

var targetFilePath = Path.Combine(binPath, "Example.png");
File.WriteAllBytes(targetFilePath, imageContent);

Images

Example.tiff
Example.png

[dlemstra]

It look like the image is mirrored. You can "fix" that with the .Flip() method.

[bjornhellander]

If I open the original TIFF file in Paint, Photos or GIMP, it is not flipped, so seems to be something in my code or in the nuget?

[bjornhellander]

I can absolutely flip it if I can detect that I need to flip it, but I have no idea what to base that on, since this doesn't happen for all images.

[dlemstra]

It took me a while to find it but with the help of GitHub Copilot I was able to track down the bug and fix it inside ImageMagick. This will be resolved in the next release.

[bjornhellander]

Awesome, thank you! Any idea when this will be released, just so I know what to expect? If it will take more than say a week, do you see any way to detect this specific case on my side?

[dlemstra]

I don't have a set release date because that also depends on an ImageMagick release date. So yes it might take more then a week.