[lutusp]

> How is the color adjusted?

An adept user of programs like Photoshop can manipulate the colors of an image to meet any imaginable criterion:

http://www.wired.com/wiredscience/2012/08/curiosity-sharp-ba...

A quote: "The colors in this image are not what a human standing on Mars would see — the presence of dust in the atmosphere would make the scene appear much redder. Instead, the pictures have been white-balanced to show how it would appear under typical Earth lighting conditions. This will help the Earth-centered geologists who are trained to recognize features based on how they look using more familiar light."