RedHat Linux 7.3 /KDE/ (2002) in HGC XF86_Mono mode (PCem).
XF86Config sample on 3-rd picture.

Last time I checked, PCem didn't magically expand the HGC's capabilities to support more brightness levels than just "pixel on/pixel off"... is this some shader? Or just a really good Hercules card? 😀

VileR wrote on 2023-08-06, 19:27:

Last time I checked, PCem didn't magically expand the HGC's capabilities to support more brightness levels than just "pixel on/pixel off"... is this some shader? Or just a really good Hercules card? 😀

I can't see any additional brightness levels there...

Anyway, for me there's no surprise about XFree86 supporting HGC, I did such experiments back in the era.
The primary problem was: 720x348 wasn't enough for common X11 software.
720x348 was acceptable for Windows 3.x (though 640x480 was better), but for X11 highly recommended was 1024x768.

Grzyb wrote on 2023-08-07, 07:12:

I can't see any additional brightness levels there...

PCem was probably showing true 1-bit Hercules video, or at least I assume so. But the screenshots show 'in-between' levels where there should be sharp boundaries, and XnView reports somewhat more than 2 unique colors:

It's the same thing you sometimes see with improper scaling, but the resolution seems to be original, and PCem shouldn't "anti-alias" its screenshots like that... so it's just an odd repersentation of HGC graphics.

VileR wrote on 2023-08-07, 15:45:

It's the same thing you sometimes see with improper scaling, but the resolution seems to be original, and PCem shouldn't "anti-alias" its screenshots like that... so it's just an odd repersentation of HGC graphics.

Could it be result of compression, even thought they are PNGs now? I was thinking something like the forum software processing uploads or screenshots saved as jpg at some point.

not pcem, but 86box has a 'blend' option enabled by default for hercules, could be something similar going on. I tried it out in prince of persia and with it enabled it almost looks like a 4 color mode. Turning it off gives you 1 bit color like you'd expect.

Some background on the "blend" option finding its way into 86box:
https://github.com/86Box/86Box/issues/260
[pics]Dosbox Hercules mode VS real hercules

The idea was to simulate behavior of CRT scan lines showing some appearance of intensity when horizontally adjacent pixels "bleed" into one another, or partially overlap one another, because there is no physical separation between them... or something like that. 😉

In any case, I think the screenshots in this thread show signs of interpolation rather than the blending effect.

PCem seems fine here in every renderer (Direct3D, OpenGL, OpenGL 3.0, Software)

I blame videocard driver anti-aliasing overrides on the OP.