I've recently been porting a project from all Jitter to OpenGL, and discovered that the rendering quality is much poorer when using OpenGL shaders, specifically for edge detection (jit.sobel vs cf.sobel.jxs)
The OpenGL looks very noisy and artifact-y, and with lower vertical resolution.
Here's a patch and a screenshot
— Pasted Max Patch, click to expand. —
Copy all of the following text. Then, in Max, select New From Clipboard.