Contrast Enhancement of Satellite Images Using Advanced Block Based DWT Technique

Abstract

This paper proposes enhancement of satellite image using advanced block based Discrete Wavelet Transform Technique. Contrast enhancement method using analysis of the dominant brightness level and transformation of the adaptive intensity performs the DWT to decompose the input image into a set of band limited components, called HH, HL, LH, and LL sub bands. The LL sub-band has the illumination information. The dominant brightness level of the input image is computed. The LL sub band is decomposed into three layers according to the dominant brightness level. The adaptive intensity transfer function is calculated using three decomposed layers from the dominant brightness level, knee transfer function and gamma adjustment function. To preserve the colour of the contrast enhanced image the adaptive transfer function is applied in the enhanced image. The resulting enhanced image is obtained by the inverse DWT. In this technique, the remote sensed image is split into small blocks, and each block is enhanced using advanced block based Discrete wavelet transform. The enhanced blocks are fused together and the resulting image is obtained using inverse DWT. The intensity and brightness of the satellite image will be better when compared to the Existing systems. Haar Wavelet Transform is used to decompose the image into sub-bands. The adaptive intensity transfer function is generated based on the Dominant brightness in each decomposed layer.