Technically, monochrome means one hue. (dichrome = two, trichrome = three, etc.) Technically, this image is monochrome: http://e621.net/post/show/97457/2008-candra-cat-cats_-musical-eyes_closed-feline-m

Technically, greyscale is not monochrome, it's achrome - no hue at all.

On the other hand, people have been treating greyscale and monochrome as synonyms and probably will continue to do so forever no matter what.

How should I tag, e621? Or, should we declare monochrome as an alias for greyscale?

I sense it would be a loosing battle unless you, or someone else, actively decided to patrol the tag and kept it clean.

I wouldn't advise tagging based on your interpretation, but rather stick to the wiki ( http://e621.net/wiki/show?nordirect=1&title=monochrome ) in order to avoid any "bad tagging" issues.

No hue is still only one universal hue, even if that hue is none. Greyscale is a subset of monochrome, by the same logic that black is a color.

Also, that image is not monochrome. If you look over it it has multiple different hues of blue, not just changes in brightness / saturation.

[EDIT]
For the purposes of image archive tagging, I'm honestly not certain whether something that makes intentional use of a full range of saturation and brightness yet only one hue should really be considered monochrome or just restricted palette. Essentially the 'point' (as I see it) is that monochrome images are non-achrome <grey>scale or <black>&<white> images. Something that's <black>-to-<blue> or <white>&<blue> or the like. By contrast, that Cats image (assuming it was technically monochrome) is a <black>,<blue>,&<white> image that makes full and intentional use of each of those colors as separate entities -- blue is not merely the point between black and white. Basically that monochrome and greyscale indicate a single linear scale the image is composed of, as opposed to (usually) two in a restricted palette image or three in full color.

Of course, this is kind of all personal conjecture and probably irrelevant.

Yeaaah, I'd have to agree. I wouldn't consider post #97457 monochrome either.

y'all and your colors...

Wikipedia says: For an image, the term monochrome is usually taken to mean the same as black and white or, more likely, grayscale, but may also be used to refer to other combinations containing only tones of a single color, such as green-and-white or green-and-black. It may also refer to sepia displaying tones from light tan to dark brown or cyanotype (“blueprint”) images, and early photographic methods such as daguerreotypes, ambrotypes, and tintypes, each of which may be used to produce a monochromatic image.

So, technically, black and white is monochrome.

However, I also remember being taught in art class that monochrome was black and white and another color. So that post #97457 counted. ... the idea being an image who didn't have contrasting colors.

The bottom line is this is really an ambiguous topic. Real painting is based off of mixing and blending and so on and so forth. Look at this: http://2.bp.blogspot.com/_Eiwce13X738/R4CGnohFUmI/AAAAAAAABMM/jSou2o71XGc/s1600-h/MaineCoast.JPG

According to the artist, that painting was done with black, white and burnt sienna. He called it "limited palatte"...

I dunno. Part of this is the problem between digital painting and real painting, as well as people's conceptions of what words mean.

I think.. I'd suggest:

monochrome = black-and-white, or blue-and-white or red-and-black or similar - post #94481 post #95284
limited pallet/restricted palette = few color = spost #93127 post #77100 post #62494 post #70524

Personally, I'd love to have different tags spreading it out furher so a black and white pencil cketch and, say #94481 up there are not regarded as the same thing. I also can't come up for a word for those images you see a lot where it might be black and white except for one or two spots of red for emphasis (dripping blood, glowing eye, etc)

TL;DR - this is a confusing, horribly un-black-and-white topic... ironically :p

SnowWolf said:
So that post #97457 counted.

I'm seeing green in there too, around the sparkly magic bits in his palm. Maybe you can edge the line and call some of that highlighting cyan, which is still a shade of blue, but that's really pushing it.

I looked at it on both of my screens and I still see shades of blueish. It MAY notbe the same exact blue as is the rest of the piece, but.. it's hard to say. Especially if it's a digital work. It's not like the real painting I linked where the artist firmly said what colors he used. I think it'd count under the idea of black and white and another color. :)