This is an experimental feature in Picasa 3, that lets you search for all the photos with a color scheme. Google searches for Red, Orange, Yellow, Green, Blue, Purple and BW photos. We wish they would have included a colour picker for this feature. Go to Tools > Experimental, and search for and click a colour. The orange search returns everything from red to yellow. The green and blue searches are most
accurate. The black and white searches returns all pale and grey colors, not photos that are strictly black and white.