Emulation New scaling method for emulation?

[Oskar.Dandy]

The DS's screen resolution of 256x192 is lower than many of the systems emulated on the DS. The Super Nintendo for instance has a 16.67% taller resolution than the DS of 256x224, which traditionally leads us to two methods of displaying a SNES image on a DS: Scaling (left), and Cropping (right).

Neither solution is ideal as the scaling results in garbled pixels and cropping results in important information being obfuscated. So, what can we do instead? Let's consider the raw SNES image:

Spoiler: Raw SNES image

For most SNES games, there's definitely information we can afford to obfuscate, so here I've chosen to crop away the top 4 pixels and the bottom 9 pixels. This results in a vertical resolution 211px, which we could then scale down to 192px...

Spoiler: 211px to 192px

This doesn't look half bad as it's only a 9% downscale, but we can do better by selectively scaling. In most games, your eyes will focus on two things: (1) The centre half of the screen, and (2) the HUD on the top. This means there is a 27px tall area and a 106px tall area which we can preserve, and then your eyes will easily ignore any scaling in the rest of the screen.

Spoiler: Area to preserve

So, I propose scaling the bottom 52px down to 45px, and then gradually scaling the 26px tall region inbetween the HUD and the centre into 14px. I stress the importance of not shrinking the entire 26px by a whopping 46% as this would squish the region too much; rather, of this 26px, shrink the bottom 13px into 8px and the top 13px into 6px.

Spoiler: Scaling breakdown

I think the results look very nice! This method preserves all of the important information whilst minimalising the effects of scaling.

Here is a comparison of all the different scaling methods, so I'd like to hear which you think looks best:

Spoiler: Scaling comparison

I'm not a coder. I'm just proposing a solution.

 

[FAST6191]

Flashbacks of my old TV that attempted something similar to generate widescreen -- arms reaching across the screen or from the side of it were quite freaky.

I would probably suggest a version of what one of the megadrive emulators used to do on the DS and allow you to move the screen or do it automatically in response to controls (if you were moving left you probably wanted to see that side anyway).
All those methods showcased are fine if you are editing a video (or indeed not fine but better than letterboxing) but for real time on a console that is both using tile size and already running close to the limit to even attempt most emulation efforts in the 16 bit world (there is a reason most special chip games don't work) it is a rather more tricky prospect.

 

[Oskar.Dandy]

but for real time on a console that is both using tile size and already running close to the limit to even attempt most emulation efforts in the 16 bit world (there is a reason most special chip games don't work) it is a rather more tricky prospect.

These emulators already do scaling, so excluding certain scanlines from the scaling should be computationally cheaper since you're not manipulating the entire framebuffer