IHS Image Merge Options

 This allows combing 2 or 3 data sets into one layer.


The color scheme is variously called HSI,  IHS, HSL, or HSV.  There are forumulas to go from RGB to IHS and back; some operations are better done in one or the other.  Screen display is done in RGB.

Various representations of color space, with 3 parameters (from Wikipedia). 
RGB color cube (from Wikipedia)


You can get similar results with transparency/opacity, and drawing one layer atop another.

Image/DEM Merge.   DEM elevation colors, and TM imagery merge.
DEM Reflectance Merge
Intensity (brightness) taken from a single band of the satellite image Elevation range  
Hue (chromaticity): taken from the DEM slope or elevation. Hue goes from blue at the low values to red and magenta at the high values. The default value does not use magenta, which often creates visual confusion. You can increase the hue to extend the slope/elevation color range. Rflectance value computed from DEM and surn position  
Saturation (purity) reflectance from an illumination model of the DEM, or a single value for the entire scene. Constant value,.  Change with caution; a little difference goes a long way.  

DEM/Image Merges

Map overlay hillshading

Default values represent the recommendations of Toutin (1997).

Last revised 11/27/2017