TIFF.

A tag-based raster format, which the Library of Congress format description lists in uncompressed, LZW and Group 4 variants, with the specification now controlled by Adobe. In print it earns its place over PNG because it can carry more than colour: ONYX describes TIF as supporting multiple channels beyond CMYK or RGB, which is how a white, varnish or primer layer travels to a UV or DTF RIP as a named spot channel. A PNG drops those channels, and so does a TIFF flattened on export. One more fault is common. When a transparent TIFF placed in an illustration is exported as EPS or PS, Mimaki RasterLink7 then treats the whole TIFF rectangle as data, so the special-colour plate covers the rectangle instead of the shape, and Mimaki says to save it as PDF. Open the file in a second program before upload and count the channels.