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Resolution and Shaders



  • So, I've configured my pi 3B+ to run at 720p for a number of reasons. It allows me to use integer scaling with a full sized image on my TV. It also seems to make menu transitions a bit smoother in some cases.

    However, some form of shader or filtering is a must for me. I like to at least come close to emulating the look of original hardware, or at least as close as I can without input lag while maintaining 60fps.

    My question is about how well CRT shaders will work in 720p. Specifically, are Zfast and CRT Pi going to look nice with many fewer pixels to work with? I could use bilinear filtering, but that is a last resort for me.


  • Global Moderator

    if your TV is 1080p there's not much point running 720p on the pi, since your TV will have to scale it to 1080p anyway, and your TVs scaler is likely even worse than the pi's. if TV is 720p max, then sure!

    as for the quality of the CRT shaders at 720p - why not try? it takes seconds. i believe the general rule is that a scanline shader needs approx 4 vertical pixels for every game pixel to look good. so for a 240p game, you'd want 960 vertical pixels, which 720p is less than. at 720p it's a 3x vertical scale, which means the scanline and pixel line have to share a pixel, which is going to make the scanlines look a little blurred i think.

    that said, just give it a try and see what you think.



  • I did give a try a few minutes ago. If I sit far away from my TV the shader looks okay but if I'm up close I can tell a difference. I don't know enough about the inner workings of shaders to say exactly why it looks worse up close, but it does. Hmmm.. I guess it's back to 1080p then as a nice shader is more important to me than marginally smoother menus.



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