OrderedDither arguments

[sadata7]

I'm trying to replicate the following command in C#:

convert input.png -ordered-dither o8x8 output.png

Here's what I've tried:

image.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
MagickImage mi = new MagickImage(stream.ToArray());
mi.OrderedDither("o8x8");

The last line above results in an the error: "ImageMagick.MagickOptionErrorException: InvalidArgument ordered-dither : 'o8x8' @ error/threshold.c/OrderedDitherImage/1944"

Where can I find a list of valid string arguments for OrderedDither? I haven't been able to find any documentation or examples.

Thanks.

[dlemstra]

Which version and platform are you using? I am on Windows and using the latest version and I can execute this code without any issue?

using var mi = new MagickImage("logo:");
mi.OrderedDither("o8x8");

I suspect that you are not on Windows and that you are using the tiny build-in threshold.xml configuration. You should probably use MagickNET.Initialize at the start of your application to make sure that the embedded resources are saved to disk and used.

[sadata7]

You are correct that I'm not on Windows. I'm running .NET 6 on Linux Mint 21. The only package I could get working is Magick.NET-Q16-AnyCPU (whatever the latest version was as of yesterday). I added MagickNET.Initialize at application start, but it didn't make a difference. Here is the full error:

Unhandled exception. ImageMagick.MagickOptionErrorException: InvalidArgument ordered-dither : 'o8x8' @ error/threshold.c/OrderedDitherImage/1944
   at ImageMagick.MagickExceptionHelper.Check(IntPtr exception) in /_/src/Magick.NET/Exceptions/MagickExceptionHelper.cs:line 18
   at ImageMagick.NativeHelper.CheckException(IntPtr exception) in /_/src/Magick.NET/Native/NativeHelper.cs:line 27
   at ImageMagick.MagickImage.NativeMagickImage.OrderedDither(String thresholdMap, Channels channels) in /_/src/Magick.NET/Native/MagickImage.cs:line 6830
   at ImageMagick.MagickImage.OrderedDither(String thresholdMap, Channels channels) in /_/src/Magick.NET/MagickImage.cs:line 4344
   at ImageMagick.MagickImage.OrderedDither(String thresholdMap) in /_/src/Magick.NET/MagickImage.cs:line 4329
   at HalftoneTest.Program.GetDitheredBrush(Int32 r, Int32 g, Int32 b) in /source/dithertest/Program.cs:line 100
   at HalftoneTest.Program.Main(String[] args) in /source/dithertest/Program.cs:line 39

[sadata7]

Dirk, I was able to fix the problem by creating a config folder in my project and copying the contents from this link, which includes the full thresholds.xml file, into the folder and then passing the path to the MagickNET.Initialize(path) call and everything seems to work now. Not sure why these steps are needed, but thanks for the tip. (P.S. I also had to create an empty configure.xml file before it would work.)