Is there a tag for images that have a pallet of only 16 colors? If there isn't would there be any need to create one, or are images with only 16 colors so rare that there wouldn't be much point?

What is the image in question? I would tag it as limited palette.

When I checked out the image at:
http://danbooru.me/posts/1667420
I think it only had 16 colors. Thanks for the feedback.

@Bugbo: Just for future reference, you can ask questions like this in topic #12251 ("How do I tag this?").

I disagree with tagging post #1667420 as limited palette. The tag is for a "small number" of distinct colors, and 16 seems like a bit of a stretch. For most pictures with this tag, I can count on one hand the number of distinct hues, but this image is significantly more colorful than that, and that's before taking into account the fact that it's dithered to look like there are even more colors.

If we expand the definition of this tag to include anything and everything with 16 colors, then we'll have to use it on loads of pixel art and old game CGs (the pc98 art, for instance). This reaches well beyond the intended scope of this tag, I think.

there's actually a tag 16_color (posts deleted) started a long time ago by the OP, just saying.

Back in the days when computer technology was young we used the term EGA for 16 color pallet, CGA for 4 colors, and VGA for 256 colors. Though I don't know if any of those would be any more or less desirable.

Those are not very intuitive to tag with, considering the difficulty of figuring out if an image has exactly 256 colors or four colors.

tapnek said:

Those are not very intuitive to tag with, considering the difficulty of figuring out if an image has exactly 256 colors or four colors.

Question for those who know the technical details of image formats: Just out of curiosity, is this something that could be automated in the same way as other metatags? It seems to me that one might be able to extract this data from a GIF or 8-bit PNG so that users could search for images by number of colors, just as we can presently search by height and width. And even if it is possible, would it be worth the effort?

I don't know about Ruby's libraries, but Python has the PIL library that can do the above with the getcolors method, so it should be possible.

I was thinking of a more complicated route of using ImageMagick and using its identification functions to get the number of colors but I didn't think of Python or Ruby having libraries that can do just that.