To access the largest number of Google Image Search filters, it is best to use the Advanced Image Search Dialog. Image Search also accepts the operators: site:, filetype: (image file type, not page file type), and imagesize:.
But did you know that you can also affect some advanced filters (for which there are no operators) by adding specific keywords to your search?
Using a color name, you can affect the color of results. An illustration is green cats that mostly arrives at Christmas cat pictures as above. (Creative uses, anyone?) For black-and-white images, use black and white: black and white moscow. (I had also tried non-standard color names, but it did not work.)
Not practical (I think), but fun: naming an image size like icon, small, medium, or large finds images of that size; for example, small picasso finds small images.
Google ignores regions and aspect ratios in a search string, but there wouldn’t be a need for that.
Image search is an underused technology. To learn about its other nifty features, check out this class.