Google has been testing different color filter button icons in the image search results for some time now and it seems it is fully launched now on both desktop and mobile.
I personally see it on many queries and over the past couple days, I've been hit by tons of people reporting this as a new feature including @BruceClayInc, @KyleW_Sutton and @timothuney.
Here are screen shots:
CARS:
FLOWERS:
Blue Flowers:
Even Guns:
Forum discussion at Twitter at @BruceClayInc, @KyleW_Sutton and @timothuney.
