XnView Software

Actually, Picasa has had a "filter by color" functionality for years and I have found it quite useful.

In Picasa, go to Tools->Experimental->Search For

... and select one of the named colors in the list. Works pretty well.
Thanks. Didnt know it, im usually afraid of trying experimental stuff ...

And the main question: It is really useful?
Cant speak for others but to me it would.
I have a lot of images i found on the internet over the years, i get them mainly for art inspiration and the like. Say i want something sad, i search for black/dark blue pictures, something warm > yellow/greish ...

Would it be possible to add to xnview MP browser a filter/sort by color option, like googles image search tool?