First post, by kurkosdr
For quite a while, I have been using the "normal2x" scaler (along with ddraw output) to scale my 640*480 games to 1280*960 (windowresolution is set to this resolution in the settings). This is effectively results in 2x scaling by line repeat, which is a decent scaling option in my opinion (it doesn't introduce artifacts/spurious detail like the more advanced scalers do).
However, some old 1280*960 LCD monitors had a better way of upscaling a 640*480 image by averaging the lines. Basically, they took the 1st and 2nd line, and averaged the values to create a new line in-between, and then the 2nd and 3rd line to create a new line, and so forth, for both dimensions (first vertical, then horizontal). This resulted in a 1279*959 picture that was very smoothly scaled. Usually the last line in both dimensions was repeated to create a 1280*960 image.
This is actually something we use a lot in the video industry, for example to scale 352*240 to 704*480. It results in absolutely zero artifacts/spurious detail while remaining smooth (no jaggies).
Is it possible to achieve something similar with DOSBox? I know you can use the opengl output to get bilinear , but I don't know if this"bilinear" achieves the above effect when used at 2x the window resolution. And what should I set the "scaler" option to? "normal2x" or "none"?