Retro Graphics Toolkit
From Sega Retro
Retro Graphics Toolkit is a useful graphics importing and editing tool written by Sega16.
Features
Image importing. Supports many common formats such as JPG GIF PNG and more
Dithering which a choice of different algorithms.
Tile editing.
Can automatically assign palette row to tiles based on content of tiles. (Which tile looks best using which row).
Both Sega Genesis and NES support.
Sega genesis Shadow Highlight mode
Save compressed tiles and tilemaps. Supports [Nemesis_compression] [Kosinski_compression] and [Enigma_compression]
What makes Retro Graphics Toolkit better
Retro Graphics Toolkit aims to be an all in one graphics editor for Retro console systems.
Retro Graphics Toolkit stores both the dithered tiles and true-color tiles meaning that if you alter the palette the original tiles will be preserved and the graphics won't have to be reworked. Just re-dither.
This makes cross platform graphics very easy. Also Retro Graphics Toolkit makes alpha transparency very easy you can import a PNG file with alpha transparency and it will be preserved also the tile editor allows you to edit both the true-color (which includes alpha transparency editing) and the output tiles.
Color 0 in the palette entry will be what is assigned to transparent pixels. So in short Retro Graphics toolkit makes worrying about color limitations a thing of the past.