Color & Brightness Correction + Light Dithering
Here's a more complete set of comparisons.
All these images are 8-bit color data rendered via software in a 8-bit color mode using the vanilla Quake palette. Without colored lighting, and without texture filtering.
Lightmaps are rendered using a separate surface cache, which is combined with the texture in realtime.
The lighting has four steps of dithering applied to it now. Each dithering step is done on a different step of the rendering, so they're actually multiple different approaches to fix different aspects of the vanilla software renderer's limitations.
These comparisons are extreme cases, which are quite common for completely custom textures in maps designed without the original software renderer in mind. The better the texture & palette combination is, the smoother the resulting image will be, with the color differences being more subtle. I already have a method for generating an optimal palette from 24-bit images, so a game made from the ground up for this engine should look significantly smoother than this.
I've still got to propagate these color corrected lighting modifications to the rest of the renderer (water, skies, and sprites first; MDL model rendering needs a complete update). Afterwards, I'll start preparing some completely custom content for a demo.
No correction, no dithering. Exactly the same as vanilla Quake:
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s0_correctionOff_ditheredlightOff.png
No correction, but with 3-step lighting dithering:
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s0_correctionOff_ditheredlightOn.png
Color & brightness correction enabled, but dithering disabled:
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s0_correctionOn_ditheredlightOff.png
Both correction & dithering enabled:
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s0_correctionOn_ditheredlightOn.png
Other comparisons:
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s1_correctionOff_ditheredlightOff.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s1_correctionOn_ditheredlightOff.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s1_correctionOn_ditheredlightOn.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s2_correctionOff_ditheredlightOff.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s2_correctionOff_ditheredlightOn.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s2_correctionOn_ditheredlightOff.png
http://www.quaketastic.com/files/screen_shots/retroquad_dwmtf_s2_correctionOn_ditheredlightOn.png