I took this picture after enjoying the Gay Vaynerchuck winelibrarytv blog and watching him taste about a thousand bottles of wine. Suddenly I was versed in wine tasting and could write content for wine sites. And wine sites needed images too. But the sites were looking to host dozens of articles. Plain text is a drag in website design.
A rich shading will have associative rich keywords in associative meaning. Think about the types of color labels your Crayola set has. Those make excellent keyword and descriptors for the images. Burnt Siena, Copper, Silver, Navy, Indigo, Bronze. This neon sign appears as scarlet, lipstick red, neon red, and bright red. Someone looking for some visual excitement may even need some words describing the texture, such as pattern or words like focused, shadows, and neon effect.