Filter for B&W images

[ubacher]

Could the COLOR filter be enhanced with an option to select only B&W images?

(Next thing we know someone will request to filter for tinted B&W images)

[Mario]

What is a B$W image?
How do you define a B&W image?

An image with only black and white pixels? (that would be Black & White). Or do you mean grayscale images?
An image with gray scale pixels where every pixel has the property Red = Blue = Green ?
What if the image has been gray scaled by applying a Luminescence or other conversion which produces a 'grayscale' image but the R,G,B values are not identical.
What with images which use a tinting of half-toning color profile?

Your FR will be really hard to do for general cases. Check out, for example, this discussion:

http://www.imagemagick.org/discourse-server/viewtopic.php?t=19580

What you consider B&W may be totally different from what others consider B&W or grayscale or half-toned or...

[ubacher]

I used B&W in the meaning of analog B&W film. This, in the digital age, is correctly called gray-scale.

Not sure how computationally difficult it is to determine if all pixels are R=G=B, or in Lab terms where
a and b = 0.
There must be some rough analysis being done for generating the histogram. Is this done by the GPU?

[Carlo Didier]

This is something that would also like to have, but it's technically too complicated (i.e. CPU heavy) to realize, I'm afraid.
One rough (but not totally reliable) way would be to take the thumbnail, convert it to greyscale and compare it to the original thumbnail. If there's no difference, then it's most probably a B&W image. But even that processing would be quite heavy.

[Mees Dekker]

I would suggest that you make a category or an keyword "B&W" and assign all pictures you consider B&W to that category or keyword manually.

After that, selecting them is a piec of cake. But yes: it involves some work initially and after that some discipline to do that every time you import new pictures. Create a Favorite to work faster on this.