Kaiser Crater Dunes - False Color

The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. This false color image shows part of the floor of Kaiser Crater. Kaiser Crater is 207 km (129 miles) in diameter and is located in Noachis Terra west of Hellas Planitia. This sand dune field is one of several regions of sand dunes located in the southern part of the crater floor.

With enough wind and sand, sand dunes are formed. Dune morphology typically has a shallow slope on the side the wind is blowing from and a steep face on the other side. The lighter part of the dunes in this image are the steep slopes. Wind blows sand particles up the shallow slope and then the particles 'fall' off the crest of the dune down the steep side. With time, the constant wind will move the crest of the dune forward. Depending on the amount of available sand, dunes can grow to large heights and sizes. The dunes in this image are moving west – towards the left side of the image. Dark blue in this false color combination are typically basaltic sand.

The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.