Value defines how light or dark a given color or hue can be. Values are best understood when visualized as a scale or gradient, from dark to light. The more tonal variants in an image, the lower the contrast. When shades of similar value are used together, they also create a low contrast image.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).