Ok, so I know that sierra famously used scanned images/paintings/etc for the backgrounds in VGA SCI games. I have read somewhere that they developed their own "codec" for scanning the images in (does that mean their file format?) But what I'm interested in is how the images were processed after being scanned.
Specifically, did they use proprietary tools for editing, or something like deluxe paint? How did they reduce the colour depth to 256 colours? I have seen a lot of games reserve the first 32 colours for the UI and other fixed items (like inventory, views, etc), whilst the rest of the palette was dynamic, depending on the background. I would like to know more about their dithering techniques.
For the most part the dithering looks like it's a kind of ordered dithering method, and then touched up manually, but it could be something else.
Does anyone have any insight on how it was done?