Framelet Based Image Fusion for the Enhancement of Cloud Associated Shadow areas in Satellite Images

In this paper, a framelet-based image sharpening algorithm was developed to enhance cloud-associated shadow areas in satellite images while preserving details underneath shadow areas. The developed algorithm utilizes framelet analysis to decompose cloudy images into several frequency level components. Image details underneath shadow areas are more preserved in this method compared to wavelet based methods. The developed technique is implemented on a cloudy Landsat7 Panchromatic subscene. The results showed that the developed technique was successful in enhancing the cloudy image through preserving the obscured details underneath the cloud associated shadow areas. Framelet based technique is having ability to maintain such details under shadow areas. Generally, two or three framelet decomposition levels were found to be sufficient for the analysis because the number of artifacts will increase with increase of number of decomposition levels.