Compositing or extending a 32-bit magickImage caps the pixel values to 16-bit (65535)

Magick.NET version

12.1.0.0

Environment (Operating system, version and so on)

Windows 10 x64 - Visual Studio 2019 v16.11.9

Description

Goal: merge two 32-bit images.

After extending a 32-bit image, all pixel values are capped to a value of 65535. After compositing a 32-bit image, the pixel values of the original image are correct (can be higher than 65535), but the pixel values of the new/added image are also capped at a value of 65535.

Steps to Reproduce

images.zip

1. Download test images added as attachment
2. Set path1 and path2 to the location of those images
3. Call the functions below:

Example 1: Extent

static void ExtentImage(string path1, string path2)
{
            IMagickImage<float> image1 = new MagickImage(path1);
            IMagickImage<float> image2 = new MagickImage(path2);

            IMagickImage<float> result = new MagickImage(path1);
            result.Depth = 32; // already has a depth of 32, but added it just to be sure
            var pixels = result.GetPixelsUnsafe().GetValues(); // has pixel values above 65535

            result.Extent(image1.Width + image2.Width, image1.Height);
            var pixels_extent = result.GetPixelsUnsafe().GetValues(); // pixel values are not higher than 65535
}

Example 2: Composite

static void CompositeImage(string path1, string path2)
{
            IMagickImage<float> image1 = new MagickImage(path1);
            IMagickImage<float> image2 = new MagickImage(path2);

            IMagickImage<float> result = new MagickImage(path1);
            result.Depth = 32;
            var pixels = result.GetPixelsUnsafe().GetValues(); // has pixel values above 65535

            result.Composite(image2, image1.Width/2, 0, CompositeOperator.In);
            var pixels_comp = result.GetPixelsUnsafe().GetValues(); // old part of the image still has values above 65535, but new (added) image is capped at 65535
}

[dlemstra]

In the next release clamping will be disabled by default when extending an image.

[CFekkes]

Works like a charm, thanks a lot Dirk! Personally would disable the clamping for HDRI by default. It’s a bit confusing that this happens automatically.