Meanwhile, on Mars, the Opportunity rover has reached Endurance Crater after days of travelling across the sandy plains of an ancient seabed. NASA/JPL has been absolutely awesome about releasing downloaded mission images from Mars to the public, and I’ve been eagerly watching the latest Navcam and Pancam archives for new photos.
The rover’s Pancam (panoramic camera) uses filters for blue, green, red, and infrared wavelengths, so images taken with each filter can be spliced and combined right at home, with a channel-based imaging application such as Photoshop, to produce approximate true-color images like this beauty. It’s harder than simply cutting and pasting each B/W filtered image into the R, G, and B channels, however: as discussed here on the BABB (Badastronomy.com bulletin board), only the left camera uses visible light wavelengths, and exposure times vary for each image, which can throw off the “true” color of the combined channels. More technical info on the Pancam here.
Keith Laney, digital imaging specialist for the mission, explains color balancing methods in great detail, and offers up some beautiful color Martian landscapes from Spirit and Opportunity. (Lots of photos; have a fast connection.)