So, let me get this straight:
You’re saying that
A) grayscale implies monochrome
B) black and white implies monochrome
BUT
C) black and white should not imply grayscale
?
From a technical point of view, black and white should of course only apply to images that are truly binary, ie a pixel is either black or white. Anti-aliasing already technically makes it grayscale, although I can look past that for image tagging purposes.
It also depends on how you look at a picture. Consider the following, and assume monochrome kinda works like grayscale but for a specific color (kinda like the HSV color model):
A) any black and white pic can be converted without loss of information into a grayscale image
B) any black and white pic can be converted without loss of information into a monochrome image
C) any grayscale image can be converted without loss of quality into a monochrome image
the thing is that A is debatable: while B and C are true by their very definitions, A is up for debate because saving a truly binary image as grayscale adds unnecessary information. It is true from a “can I convert this without loss of quality” point of view, but not from a “save a picture in the color model optimal for that sort of image”
Regardless, anti-aliasing or jpeg scanning artefacts aside, I don’t think black and white should be used on images that intentionally use more than 2 colors, where those two colors are 1) the background color (what about transparency?) and 2) ANY shade of gray (or even any color?).
Thus, a pencil sketch in value #999 on a transparent background, would that also be ‘black’ and ‘white’?
Interesting topic btw. Really gets you thinking about tags and color models and stuff. You’d also have to think about definitions. I thought a bit about putting it into formal HSV definitions and failed.
