One thing you can do to improve the quality of Graphics 8 + 10 renders, or any other mode 8 combinations, is to do some floyd-steinberg dithering on the mode 8 picture. I use GIMP to do this, it makes some very nice renders.
Here are some examples ... I did these using ICE 0+10 full frame flicker but they should also work in bitmap 8+10
Very true ... although with GIMP there are three types of dither you can do (Floyd Steinberg, FS with reduced color bleeding, and positioned). The second Floyd Steinberg tends to smear the colors a bit less and can make some blended pictures look better.
Also, on the 8+10 renders, one thing you can also do is to change PF2 each scanline ... use the Graphics 10 color for PF2 on the mode 10 lines, and on the mode 8 scanlines, set PF2 to the same color as your PM0 BG register (in this picture, it is 0, black). This will help stabilize the picture and not make it have the gold tint. That's close to the method I used on my ICE picture.
Also a good idea is to try Altering PF1 on the mode 8 scanlines, and play with the brightness on those lines to see if that helps to reduce the flicker. PF1 in graphics 8 controls the brightness of the pixels.
Some of those pictures would look good in a double Graphics 9 interlace. You want photographs that have only two dominant colors, ideally colors on opposite sides of the color wheel. So you would, for instance, do a green render and a magenta render (or whatever the two main colors are), then switch COLBK between these two colors every scanline.
An example picture is here ... ->link<- .. it is full frame flicker, but again could be done in scanline interlace.
On the water pic, I did a mixture of orange and blue to get the mixing effect. You get 256 shades, and the picture really looks good if you turn down the brightness on your monitor.
The best combinations for these colors tend to be blue - yellow ($80-$10 on NTSC), green-magenta ($c0-$50), or red-cyan ($a0-30) ... when blended together, these make grey, giving you a three hue picture. Sometimes, using the two most common colors in the picture works too.
Another thing I have been thinking about trying, is using the missiles in these pictures, and the GTIA setting that turns them all to PF3. Graphics 9 shows through the missiles at this setting, and changing the PF3 colors on the scanlines could also add more color to the picture.
Maybe a good combination to try would be 10+15. The aspect ratio would blend better, and when you are combining the same PF register in both pictures it will not flicker. You can also blend the PF colors like this:
To make a checkerboard pattern and reduce the flickering.
I've done similar in text mode using Antic 4 and mode 10. In bitmap you would only get 30 colors, not 35, because mode 15 has no PF3. Might look better than my pictures though.
This combination is really good for converting Commodore 64 pictures too. I came up with a color mapping that allows conversion from C64 multicolor mode pictures.
That looks very good. I did my own version, using 12+10. Not as high res as yours, but I think it looks good. Also including my source and my own Graphics 10 render in case you wanted to try it with 8+10
I wonder if it might be possible to do a port of the game using 12+10 ... or, I could render the screen in Antic 5 (13+10) to make it like Sheddy's Space Harrier. Just some thoughts ...
Also included source .asm. To recompile this yourself you need to re-render .fnt and .scr files from g2f. Also I changed one of the greys, into a blue .. that way it blends with the Yellow on Graphics 12 and makes the road grey.
I like that last one. I did similar experiments using 12 + 9 to get the extra PF3 color. The downside is you have to change modes every character line (8 scanlines) so it flickers more. You should also try this on monochrome pictures. In parts of the picture where you are blending the same luminances, you can do a checkerboard effect to reduce the flicker.
Also, a question: On the cat picture, what if you changed BAK on the mode 9 lines to the same gold as the cats eyes, changed BAK on the mode 15 lines to a blue (opposite the color wheel from yellow) and also made the grey shades in 15 into the same shade of blue?
When you mix blue and gold you get greyscale, but it might actually make the cat's eyes more gold than they are now.
Set GPRIOR so that all the missiles get PF3 color, set PF3 to dark red, maximum width, then overlay them on her eyes ... PF3 can be made to mix with the Graphics 9 shades and it will eliminate the grey in those parts of the picture.