Digital Image Processing: A Remote Sensing PerspectiveFW 5560Lecture 5Additional Display AlternativesAdditional Display AlternativesThe RGB color coordinate system is the most widely used display system for scientific visualization. However, alternatives exist- such as the IHS system.RRGGBB Color Coordinate SystemArtists tend to describe scenes not in terms of red, green, and blue but as hue saturation and intensity (HSI) We do not seeblue, but as hue, saturation, and intensity (HSI). We do not see things as quantities of primary colors mixed in certain proportions. We see the brilliant orange of a sunset or the dark, muted greens of a forest. We see things as colors, or hues, that either have a washed-out look or have deep, rich tones. This means having low or high saturation respectively A brightThis means having low or high saturation, respectively. A bright afternoon sun gives everything a high-intensity look, while dusk provides dark images of low intensity.HSI space–Gray levels are located on diagonal of color cube joiningGray levels are located on diagonal of color cube joining black and white vertices– Saturation is distance from this diagonalHi l dthidi l–Hue is angle around this diagonalIntensity, Hue, Saturation (IHS) Color Coordinate SystemThe vertical axis represents intensity (I)which varies from black (0) to white (255) and is not associatedand is not associated with any color.The circumference of represents hue (H),hi h i th d i twhich is the dominant wavelength of color. Hue values begin with 0 at the midpoint of red tones and increase counterclockwisecounterclockwise around the circumference of the ht ldsphere to conclude with 255 adjacent to 0.If cone is viewed from above it becomes aabove, it becomes a circle. Different colors, or hues, are arranged around this circle - the familiar color wheel used by artists. Hues are ydetermined by their angular location on this wheelwheel.Saturation (S)representsSaturation (S)represents purity of the color and ranges from 0 at the center of the sphere to 255 at the circumference. A saturation of 0 represents pa completely impure color in which all wavelengths are equally representedare equally represented and which the eye will perceive as a shade of gray that ranges from white to black depending on intensity. yRelationship Between RGB and IHS Color SystemsMerging Different Types of Remotely Sensed Data for Effective Visual DisplayIntensity-Hue-Saturation (IHS) Substitution:Data for Effective Visual DisplayIHS values can be derived from the RGB values through thetransformation equations:BGBGRI++=BIBGH3−−=IBIS3−=IRGB to HSI