Logarithmic stretching
When displaying a value raster map with a representation gradual, e.g. representation Pseudo or representation Gray, you have the possibility to choose Logarithmic stretching in the raster map's Display Options dialog box.
By using logarithmic stretching you can enhance the visualization of rather small values in the map; small values in the map will be mapped on a wide range of colors. Large values will be displayed in similar colors; the majority of the values in the map are mapped on a short range of colors.
The formula for Logarithmic stretching reads:
log(x - min + 1) / log(max - min + 1)
where:
x | is a value in the map between min and max |
min | is the minimum value specified in the Stretch range, i.e. a value in the map where stretching should start. Any values in the map that are smaller than the specified minimum Stretch range value will obtain the same color as the minimum Stretch range value. |
max | is the maximum value specified in the Stretch range, i.e. a value in the map where stretching should end. Any values in the map that are larger than the specified maximum Stretch range value will obtain the same color as the maximum Stretch range value. |
See also: