Algorithm used when Fractional Scaling?

General
1

This is more for educational purposes so i feel this probably belongs in General.

I have been using Fractional Scaling as a sort of psuedo upscaler for my games as follows with a script that gets run by gamemode which runs them at 1600x900

#!/bin/bash

power=$(cat /sys/class/power_supply/ADP0/online)

if [ $power -eq 1 ]; then
    kscreen-doctor output.eDP-2.scale.1.2 output.eDP-2.mode.1920x1080@165
elif [ $power -eq 0 ]; then
    kscreen-doctor output.eDP-2.scale.1.2 output.eDP-2.mode.1920x1080@60
fi

Its simple and it does what i want as i have a 16:10 display and some games dont like it on top of it making streaming painful.

Context out of the way Im curious, is something like Lanczos used to scale the screen when setting Fractional Scaling? Whats the layman’s overview for it if anyone would be so kind?

This looks surprisingly good on my display and the resolution scale i run at, I havent tried more extremes but even FSR cant handle that well.