What type of graphic filter you prefer ?

[R1dO]

Any option without a "*" uses software-filters, no openGL involved there.

Regarding a system with openGL-accelerated hardware, it is quite easy to spot f you have incompatible hardware. The game will crawl to a bad performing slideshow when selecting a "*" filter (< 1fps) on those. This is based on my experience with a 2005 netbook .

I find it quite remarkable that most filters have no visible effect on your system, things like scale (and the like), HQ alike and SABR sabre alike have a tendency to smooth the edges making the interface more rounded.
I kinda suspect that you are running with a display resolution comparable to the game (640x480 if i'm correct), in that case the scalers probably don't have anything to scale. But this is bordering on my knowledge and might be wrong.

[wolfreal]

I think disable is vanilla.

[RockDoctor]

it is quite easy to spot f you have incompatible hardware. The game will crawl to [...] (< 1fps) on those.

OK, so there's acceleration.
I spent a number of hours fiddling with graphics options when I first met a Xenix system in 1989, then got back to doing paid work . It's not something that I pay much attention to.

I find it quite remarkable that most filters have no visible effect on your system, things like scale (and the like), [...]
I kinda suspect that you are running with a display resolution comparable to the game (640x480 if i'm correct),

1366 x 768 according to ControlCentre/Displays. One of these days I'll write it down, because I never remember it. I'm trying to remember what the resolution is if I hook the laptop up to the telly is, but I'd need a longer lead to use that more than occasionally.
I only gave each filter a couple of seconds test. They may have had more subtle effects that I just didn't notice.

Still getting whacked by 4 cyberdiscs on mission 2, a terror attack. Much dieing of the Rookies.

[KZad Bhat]

The actual original resolution would have been 320x240 at most, possibly 320x200. It was a standard VGA game, and standard VGA can only achieve 8 bit color at up to 320x240. If it goes to 640x400 or 640x480, you can only get 4 bit color.

[Meridian]

320x200

[Kilgore T.M. Replicant]

It was a standard VGA game, and standard VGA can only achieve 8 bit color at up to 320x240. If it goes to 640x400 or 640x480, you can only get 4 bit color.

Not quite sure on the "standard" but Mode-X went up to at least 320x400 and there was an unchained 640x400 8bpp mode. At least every VGA had the required 256 kB VRAM.

As for the topic:

An incomplete list of reasons for rejecting patches:
- cosmetic OpenGL shaders
   * No.
 - Scale2x, HQ3x, ...
   * Nearest/linear via OpenGL should be enough.

I'd take GUS emulation over pixel fudging.

[The Reaver of Darkness]

All of the old 16-bit VGA DOS games I remember were using 320x200 resolution. It seemed to be an industry standard at the time.

[Kilgore T.M. Replicant]

All of the old 16-bit VGA DOS games I remember were using 320x200 resolution. It seemed to be an industry standard at the time.

Industry standard indeed. Many 32-bit VGA DOS games used 320x200 too, for example Doom and, um, XCOM. It is much simpler for the programmer than the larger resolutions.

"Not only is there a high 256-color resolution, there are lots of higher 256-color resolutions, going all the way up to 360x480-and that’s with the vanilla IBM VGA!" -- Abrash, Michael: Graphics Programming Black Book, chapter 31, page 589. PDFs

[The Reaver of Darkness]

Many 32-bit VGA DOS games used 320x200 too, for example Doom and, um, XCOM.

Doom had 16-bit color (I think) and X-Com had 8-bit color.

I do recall playing Tomb Raider 2 as a DOS-compatible game and it had 32-bit color but it was one of the first to have 32-bit and one of the last to be DOS-compatible.

[Kilgore T.M. Replicant]

Doom had 16-bit color (I think) and X-Com had 8-bit color.

All used 320x200 with 8-bit color. Doom and X-Com are 32-bit games because they run on 32-bit 386 processors using 32-bit code and 32-bit address space; that DOS4G/W thing you may have seen when starting these game is a good indicator of 32-bitness. A completely random example of a 16-bit DOS game using the same graphics mode would be Master of Orion, which ran on the 16-bit 286 processor. (Now about 16-bit games using larger-than-320x200x256 modes... maybe Pinball Fantasies?)

I do recall playing Tomb Raider 2 as a DOS-compatible game and it had 32-bit color but it was one of the first to have 32-bit and one of the last to be DOS-compatible.

I suppose this is something artists and programmers can never agree on, but this is honestly the first time I've encountered an gfx-bitdepth-is-game-bitness argument outside game console marketing material.

Somewhat on topic: while I do love the blocky pixels, linear scaling seems better than nearest for the aspect ratio correction.

[The Reaver of Darkness]

I suppose this is something artists and programmers can never agree on, but this is honestly the first time I've encountered an gfx-bitdepth-is-game-bitness argument outside game console marketing material.

It seems a more important distinction than basing it on the addressing. Unix has been 64-bit AFAIK since the days of the greenscreens, while Microsoft kept escalating the bit number as time went by. The addressing is just a non-paramount choice, while the bit number on the colors used by the graphics system is actually visibly distinguishable and grew over the years along with the technology.

[Yankes]

It seems a more important distinction than basing it on the addressing. Unix has been 64-bit AFAIK since the days of the greenscreens, while Microsoft kept escalating the bit number as time went by. The addressing is just a non-paramount choice, while the bit number on the colors used by the graphics system is actually visibly distinguishable and grew over the years along with the technology.

There big difference between 16 and 32 bit, first of all this is not address space but size of registers. Why this importation? This is because how fast processor can calculate big numbers, If we assume that we have multiple processors that have same speed but different registers then then in same time:
8bit will calculate values up to 255
16bit will calculate values up to 64Ki (64*1024^1)
32bit will calculate values up to 4Gi (4*1024^3)
64bit will calculate values up to 16Ei (16*1024^6)

And current processors aren't in reality 64bit but 256bit but because nobody use 16Ei values it calculate smaller but multiple values at once (SEE, AVX-512).

Address space grow too, but sometimes it can be bigger or smaller than processor. Some 8bit processors can have 16bit address space and today 64bit processor have only around 48bit address space (https://superuser.com/a/168121/368048)
And why its matter? It determine how big and complex game can be. Of corse in today times 90% memory is used by graphic stuff but still sometimes today games can crate things that was impossible for previous generations.

Btw UNIX on what machine? First of all Microsoft is not responsible for change of bit numbers but Intel or AMD. Second we are discussing home computers not super computers (that many times uses UNIXs).

[Kilgore T.M. Replicant]

It seems a more important distinction than basing it on the addressing. The addressing is just a non-paramount choice, while the bit number on the colors used by the graphics system is actually visibly distinguishable and grew over the years along with the technology.

OK, so Doom, X-Com, MOO1 and Starcraft were 8-bit games and Super Mario Land was a 2-bit game. Got it.

[KZad Bhat]

Not quite sure on the "standard" but Mode-X went up to at least 320x400 and there was an unchained 640x400 8bpp mode. At least every VGA had the required 256 kB VRAM.

That 256kB VRAM is why 8-bit color couldn't apply to higher resolutions, like 640x400/480. There actually wasn't enough RAM space available to accommodate that many pixels in 8-bit color mode, and any VGA with more VRAM addressable is considered to at least be SVGA (Super Video Graphics Adapter) as distinguished Standard VGA. Although it does seem from other are saying that 320x400x8 was also used, I don't think it was very common. And checking the math, 640x400x8 should have been possible, though there may have been a necessity to put other things in VRAM that prevented the full space from being available to handle it.

I even just checked the Wikipedia page for VGA to confirm a bit, and the common resolution/bit depth combinations show that 8-bit was not available for 640x400, and in fact it isn't even listed as a standard resolution, though 640x350 and 640x200 are, both in 16 color or monochrome.
Quick edit: Reading more, I found this a little lower down from the standard resolutions:Higher-resolution and other display modes are also achievable, even with standard cards and most standard monitors – on the whole, a typical VGA system can produce displays with any combination of:
 

• 512 to 800 pixels wide, in 16 colors (including 640, 704, 720, 736, 768...), or
• 256 to 400 pixels wide, in 256 colors (including 320, 360, 384...)

[Kilgore T.M. Replicant]

That 256kB VRAM is why 8-bit color couldn't apply to higher resolutions, like 640x400/480. There actually wasn't enough RAM space available to accommodate that many pixels in 8-bit color mode, and any VGA with more VRAM addressable is considered to at least be SVGA (Super Video Graphics Adapter) as distinguished Standard VGA.

My mistake. The unchained 640x400x8 mode requires SVGA [source].