RetroPaint is a semi-non-destructive image converter app (Windows 64bit only atm) which can handle
image conversion for C64 (hires and multicolor), VIC20 (sortof), ZX Spectrum, CGA (sortof), Amstrad (sortof), Amiga (2-32 color, halfbrite and HAM), Commodore 16 116 plus/4, Atari 800, Game Boy and Nintendo NES.
Feature list
The feature list is quite extensive
Reads all common image file formats, including JPG, PNG, KLA, IFF/ILBM, GIF
Export to PNG, JPG, GIF, KLA, PRG, IFF/ILBM
Release
RetroPaint was initially released as an early beta around Easter 2023. Since then there has been roughly a release each month.
Sign-up by using the link above, just under the title image.
Download
To download and give RetroPaint a spin you have to register as a tester (the program is still under development).
The signup page is here.
Real-time altering
RetroPaint works with color matching in multiple color formats and color spaces
RGB
YUV
LAB
XYZ
YIQ
HSV
HSL
CMYK
and it also has a luminance mapping functionaliy.
RetroPaint has plenty of dithering built in
Line diffusion
Floyd Steinberg
Jaris
Stucki
Atkinson
Burkes
Seirra, Sierra Two Row, Sierra Lite
Bayer, 2x2, 3x3, 4x4, 8x8
RetroPaint offers you the possibility of many filters:
Blur
Brightness and Contrast
CLAHE
Clamp
Color temperature
Gamma
HDR
Hue shift
Levels
Saturation
Unsharpen mask
With these you can alter the bitmap you are converting. There are no limits to the number of adjustments and their order in the adjustment list. You can copy/paste, save and load adjustment lists for easy re-use.
This is me turning up the brightness on the cover image from Cauldron II.
This is a single layer, YUV color matching and line dithering turned on.
You can pick any image in between and start pushing pixels on that. @60 fps on my PC @ 320x200 C64 MC.
These images are only here to show that you can simulate/emulate different platforms.
Some of these examples are NOT able to run on the actual platforms.
The dithering method used here is Floyd-Steinberg with default parameters.
Just to demonstrate that you can go from one platform to another in two clicks (if you are lucky, that is).
