Is applescript capable to count pages of a pdf file that are in colour?
I would have to look at a PDFs text to be sure but as I recall from doing so in the past color information is in the header for the PDF and does not distinguish separate color models by page. This means that there is probably no way for Applescript, or any other automation method, to distinguish if a page has color on it. You might be able to step through the PDF code element by element on a per page basis to check the color but this would most likely be too slow to be practical and potentially unreliable.