An efficient non-linear algorithm for contrast enhancement of infrared image

An infrared image contrast enhancement algorithm based on a discrete stationary wavelet transform (DSWT) and non-linear gain operator is proposed. Having implemented DSWT on an infrared image, de-noising is done using the method proposed in high frequency sub-bands which have better resolution levels and enhancement is implemented by combining the de-noising method with the non-linear gain method in high frequency sub-bands which have the worse resolution levels. According to experimental results, the new algorithm can reduce effectively the correlative noise (1/f noise), additive Gauss white noise (AGWN) and multiplicative noise (MN) in the infrared image while it also enhances contrast of the infrared image. In terms of visual quality, the algorithm is better than the traditional unshaped mask method (USM), histogram equalization method (HIS) and two methods by Gong et al. (2000) and Wu et al. (2003).