Enhancement of multispectral images using histogram explosion

Enhancement of both multispectral and true-color images is often performed by histogram modification, usually by separately adjusting the color components within a selected color coordinate system. When preservation of certain perceptual qualities is important, a perceptually based coordinate system is employed. However, independent modification of the color components seldom results in full use of the RGB display gamut unless some color values are clipped at the RGB boundaries. Preserving perceptual attributes is sometimes less important than obtaining greater displayable color contrast. This is especially true for color composites derived from multispectral images, such as those obtained by remote sensing. `Histogram explosion' is a new, multivariate enhancement method able to exploit nearly the full RGB extent without causing clipping. It functions by deriving and adjusting a set of one-dimensional histograms which lie along rays emanating from a common point in RGB space. While not generally based upon a perceptual model, histogram explosion is capable of preserving original hue values when parameters are chosen properly. Wide flexibility in the algorithm's parameter choices allows much freedom in tailoring the enhancement process. A description of these parameter dependencies and an analysis of the computational complexity are presented.