32-bit float is the default data type
…that’s what I was looking for, thanks. The docs for gmic say that -print will “Output information on selected images” so I mistsakenly interpreted the “size =” line to be telling me about the data in the file. It sounds like it is instead telling me about the internal processing pipeline, i.e. the number of floats the image represents once it is read into gmic.
Does gmic have a “show me details about the file” function? Or maybe mediainfo is the more appropriate utility for that?