High Dynamic Range Fuzzy Color Image Enhancement

High dynamic range images contain underexposed and overexposed regions. The enhancement of underexposed and overexposed regions is the main concern of this paper. The two new transformation operators are proposed to modify the fuzzy membership values of underexposed and overexposed regions of an image respectively. For overexposed regions, a rectangular hyperbolic function is used while for underexposed regions, an s-function is applied. The shape and range of these functions are controlled by the parameters involved and these parameters are optimized using the bacterial foraging optimization algorithm so as to obtain the enhanced image. The hue, saturation, and intensity (HSV) color space is employed for the process of enhancement, where the hue component is preserved to keep the original color composition intact. This approach is applicable to a degraded image of mixed type. On comparison, the proposed transforms yield better results than the existing transforms, used in, for under and overexposed regions respectively.