Gamma correction based satellite image enhancement using singular value decomposition and discrete wavelet transform

This paper proposes the enhancement of low contrast satellite images based on intensity transformation. The intensity transformation is achieved using gamma correction on discrete wavelet transform (DWT) and the better illumination is achieved by singular value decomposition (SVD) technique. The DWT decomposes the input image in four different frequency sub-bands; low-low (LL), low-high (LH), high-low (HL) and high-high (HH). The gamma correction is applied only on LL sub-band to preserve the edge information. To improve the illumination, these gamma corrected LL sub-band information are passed through SVD. The enhanced image obtained is reconstructed by taking inverse discrete wavelet transform (IDWT). The performance measure is carried out in terms of EME, entropy and signals to noise ratio.