Silent data corruption of output images resulting in incorrect colors #1985
Description
Magick.NET version
Magick.NET-Q8-AnyCPU v14.10.4
Environment (Operating system, version and so on)
Linux
Description
Starting with Magick.NET 14.10.4 (which bundles ImageMagick 7.1.2-16), images with alpha channels appear visibly dimmer after being processed with a CopyAlpha composite operation.
Steps to Reproduce
// Upload any PNG with transparency as an image
var magickImage = new MagickImage(inputStream); // PNG with alpha
// Resize with alpha preservation
using var sourceImageAlpha = new MagickImage(magickImage);
sourceImageAlpha.Resize(150, 150);
magickImage.Alpha(AlphaOption.Off);
magickImage.Resize(150, 150);
magickImage.Composite(sourceImageAlpha, CompositeOperator.CopyAlpha);
// Convert and write
magickImage.Format = MagickFormat.Png;
await magickImage.WriteAsync(outputStream);
// Result: output image appears dimmer than input, dark areas become transparentImages
Original:
Output:
