HalideSharp
HalideSharp provides bindings for Halide for C#, allowing you to write powerful image processing code that will execute on the GPU in C#. At present the bindings are incomplete, but they do cover enough functionality that you can start building real programs right now. The Halide team maintain some excellent resources for learning Halide, which I strongly recommend looking at. HalideSharp also includes ports of the first handful of tutorials so that you can quickly familiarize yourself with the minor differences between Halide and HalideSharp.
If your application is currently on Linux x64, you can get started with HalideSharp by installing the Nuget package.
For anyone interested in implementing more bindings for HalideSharp, please refer to the Development Guidelines for some important information. Similarly, issue reports are also welcomed.