Colour Display Techniques Additive Colours Subtractive Colours Colour Triangle Colour Cubes Hexagon Hexcone Hue, Intensity and Saturation Chromo-Stereoscopy

Subtractive Primaries: Yellow, Magenta and Cyan Colour mix Additive Primaries: Red, Green and Blue Subtractive Primaries: Yellow, Magenta and Cyan The colour of an object is defined by the colour of light that it reflects.

Colour Cube L & K 10.7

Perpendicular to the gray line Hexagon A hexagon is formed by the interception of the plane of projection with all six sides of the colour cube R M Y Hexagon B G C Perpendicular to the gray line

Hexcone Hexcone: When the plane of projection is moved from the white to black along the gray line, successively smaller colour subcubes are intercepted and a series of hexagons of decreasing size are produced. The hexagon at white is the largest and the hexagon at black is reduced to a point. This series of hexagons define a solid called the hexcone

Hue: the angle around the hexagon. It gives the dominant color Intensity: the distance from the zero intensity point along the gray line. It defines the brightness of a color Saturation: the distance from the gray point at the centre a of the hexagon. It reveals the purity of a color

RGB to HIS transformation

Chromo-Stereoscopy Depth perception can be created using a pair of glasses which have different refraction indices for different colours. Digital Elevation models (DEM) can be assigned with different colours to create depth perception. Refraction index red green blue wavelength

Chromo-Stereoscopy Example: Hue DEM, For depth perception Intensity TM for surface brightness Saturation SAR for surface texture (terrain shadows, forest roughness) This is a perfect combination to show the topography, surface features and natural shadows in one image

Chromo-Stereoscopy Example II: Hue DEM, for depth perception Intensity TM for surface brightness Saturation constant This combination is useful when only DEM and optical data are available. Surface features and terrain relief are shown very well using this combination

Chromo-Stereoscopy Example III: Hue DEM, for depth perception Intensity SAR Saturation constant This combination is useful to show terrain relief and shadows