Ghostscript color detection

Question

I seem to be unable to find whether Ghostscript is able to simply detect whether job is color or grayscale. I use Ghostscript for conversion of print jobs to PNG, but I also

Answer 1

A new output device has rendered this answer outdated, see the Accepted Answer.

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Until 2011, the file needed to be rasterised to see an output. Since the PDF/PS is a description of what the file looks looks like which gets rendered whilst rasterised. Even if you could do this with ghostscipt I am sure it would need to rasterize/interpret the file first then look at the output, so if you have the png's you might as well do this yourself, which will be less cpu intensive than processing the file again with GS.