The 5D Mark III has a number of Picture Styles that you can use to process your photos in-camera. Each predefined style has different color, saturation contrast, and sharpening settings:

Style Description
Auto In this case, the camera applies the photo style (but not monochrome) it thinks is appropriate to the scene. Mileage may vary from photo to photo.
Standard The default setting, this option promises sharp images with good contrast and strong colors.
Portrait This mode reduces sharpening slightly (compared to Standard) to soften skin textures.
Landscape In a nod to traditions of landscape photography, this Picture Style emphasizes greens and blues and amps up color saturation and sharpness, resulting in bolder images.
Neutral Use the Neutral style if you want to edit your photos yourself. The colors are subdued but natural.
Faithful The Faithful style is designed to render colors as closely as possible to how your eye perceives them in the daylight.
Monochrome This setting produces black-and-white photos. You can also apply four different filters (yellow, orange, red, and green) and four different toning effects (sepia, blue, purple, and green).
User defined 1–3 You have three spaces in which to save your own styles. After you create them, select them here.