I also encountered issues with overprinting when using tiffsep to convert to *.ps or pdf. It works fine for composite printing on regular printers, but it is completely unusable for color separation printing. This is because the text on the image, whether pure black, other colors, or color blocks including spot colors, will hollow out the other three color separation plates of CMYK, regardless of the color. If the registration is not good during the printing process, white borders will appear, which is unqualified. I wonder if the project team of ghostscript has not discovered this serious problem over the years?

For PDFS, I tried manually forcing the color block text on the image to overprint mode, then outputting it as a pdf file, and using tiffsep color separation to convert it to a color separation version image without any problem. In coreldraw, you can also manually set the fill and contour overprint, and then When printing ps, it's fine to select "Analog Output *.PS file" in the document overprint list on the color separation layout. However, this is obviously a very foolish approach because in normal designs, all the content needs to be manually overprinted, which will increase a lot of work. If some overprints are accidentally missed, the consequences will be very serious.