interesting response from Topaz..
Topaz Marketing (Topaz Classic)
Jan 4, 2:27 PM CST
Hello Bob,
Currently, Gigapixel's AI models have only been trained on color photos so most of the time when you run a monochrome file through the program, it outputs with a color cast. Though this is fixable in post, we don't currently have a way of stopping this process.
We apologize for the inconvenience.
Sincerely,
Topaz Labs Marketing Team