I'm sorry but in a last minute change I made a mistake in the code, and I also had some issues on specific hardware due to conditional returns, but now it's fixed and if you already have the .glsl file you should re-download it (same link).
And good news, now it's also in HLSL
JeGX, very cool, please share any screenshot
Shadow, I'm not planning to release any app soon for this, sorry. The goal is not to demonstrate the blending modes, there are plenty of tutorials and references online, but just to directly translate full-screen processes in shader code. I might just be publishing some cool results if I have any with the corresponding code.