Northern Polar Cap
About this image
This nighttime visible color image was collected on November 26, 2002 during the Northern Summer season near the North Polar Cap Edge. In THEMIS false color images at high latitudes, ice/frost is typically blue and dust red/orange. The upper ice surface in this image has a partial coating of dust, and dust is located in the ice layers as well.
The THEMIS VIS camera is capable of capturing color images of the martian surface using its 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 the use of 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.
Please see the THEMIS Data Citation Note for details on crediting THEMIS images.