Using BetterDisplay to increase sharpness of text

[Brunni132]

I see here people complaining about the integrated filter, which adds an outline to the text when scaling down, but I'm actually looking for some stronger version of that, like the "Sharpness" controls that some external displays have.

My problem is that I can only use my MacBook Pro at its native resolution, but fonts are too small (I'm getting older). If I set any other resolution, the extra blurriness invariably causes headaches and other annoyances. The goal would be to be able to have bigger fonts, but with some extra sharpness. I don't care if it looks ugly, that's how I've set up my external displays and I work fine on them.

Is it something that BetterDisplay can do? Thanks in advance.

[waydabber]

I am afraid not really. If you decrease the resolution below the native resolution of the built-in screen, fonts will become somewhat blurry indeed, I know no way around that until Apple adds a 3x HiDPI rendering mode maybe in the future.

[Brunni132]

Yes thanks. What I mean is, even though the fonts will be blurry, if there is a way to add some post-processing, to sharpen the edges (like old TVs did) then it would become bearable. That's what I do on external displays.
Apparently you have a Metal pipeline, and I know that shaders are able to reproduce even the look of old TVs (as in RetroArch), so I wonder if the APIs you are using would allow for something like that?

(As a surprising note, I actually use my display in 1x [non-retina], because the upscale makes pixels more visible; the problem with slightly blurry text is that my eye always tries to focus, and can't get it because every other line/column is blurry. At least with the big pixels it can get that done, and I don't get headaches apparently. It's just ugly and I would like the retina when working with some things.)

[waydabber]

I see. A metal sharpening effect could only work as far as the framebuffer resolution allows it - if you set the resolution lower, the metal sharpening effect itself will result in an unsharp image.

What you can do is to set the built-in screen to the native resolution, create a virtual screen with a lower resolution and stream it's contents to the built-in screen while enabling "Integer scaling" for streaming. This will disable any smoothing effect, the image will be pixelated, like on a pixel art or 8-bit style retro videogame. This technique usually aids people who want to use low res but find the default scaling with smoothing distracting.

[Brunni132]

Thank you!
So that means you have some control over how rescaling is done when streaming the virtual screen, right?
Or is it a system API and you can only choose "integer scaling" or "bilinear"?
There are other kinds of filtering, such as lanczos (variants of which, such as lanczos 3, have been used as a standard on all LCD panels from the 90-2000s, and also Windows' StretchBlt if I remember, and still in MSPaint I think), but it seems that a lot of people find it useless nowadays, and it was even removed from GIMP.
Either way it would be pretty easy to implement an upscaling (or downscaling) with this filter using a shader, provided you have control over the rendering (virtual screen -> physical screen). My question is, is that something which could be even envisaged?

[waydabber]

Yes, with local streaming a special scaling algorithm or even upscaling, frame interpolation etc could be done.

[Brunni132]

Great, good to know thanks!