PixelFormat Tiff CcittGr4 wrong on linux

Hi, i'm working with Tiff CCITTGr4 images (bitonal) and when i test in linux (net core 2.2/3.0/3.1 - libgdiplus: 4.2-1+b1) the Bitmap class give me PixelFormat.Format24bppRgb When i run in windows, PixelFormat give me Format1bppIndexed (the correct value). I've tested in mono (docker) and get wrong value too.

The test code is very simple. Having test.tif file (TIF CCITTGr4) using (Bitmap bmp = new Bitmap("test.tif")) { Console.WriteLine(bmp.PixelFormat); }

I've opened it in dotnet/runtime and them have redirected me here. https://github.com/dotnet/runtime/issues/1106

Regards Gustavo

该提问来源于开源项目：mono/libgdiplus