As a software engineer, I can tell you that the "IBM-compatible computer with color graphics" is not something you should use to project the properties of stored image from. It's just a fancy way of saying "any modern PC". Even a grayscale image requires a computer with "color graphics" - as opposed to older displays whose pixels worked in an on/off fashion.

Anyway, the scanners resolve topography, not color. I really really doubt that they can pick up tattoos, though they would have no problems showing scarification.

In any case, to me it's still a strip search, but there is no concern about color.