Satellite Image Enhancement Using 2D Level DWT

Satellite images may have been taken in very dark or a very bright situation, so the information may be lost in those areas which are excessively and uniformly dark or bright. So we have to improve the contrast of a satellite image. Image contrast enhancement is one of the most important issues in image processing. Contrast enhancement has the purpose to improve the quality images.. Satellite colour images are being used in many research fields. One major issue of these types of colour images are their poor perception. There are several methods used to enhance the perception of these images. Some of these methods are Histogram Equalization Technique, Local Histogram equalization method, Discrete Cosine Transform, and Discrete Wavelet Transform technique. All these methods face problems such as loss of image information, loss of edge details etc. A new method to enhance the satellite image which using the concept of wavelets and threshold decomposition is discussed here. The proposed enhancement technique uses 2D DWT to decomposed input image into different sub bands such as LL, LH, HL, HH. Then, enhancing the image using threshold decomposition. Threshold decomposition is a powerful theoretical method, which is used in nonlinear image analysis. Here edges are detected through threshold decomposition and these edges are sharpened by using morphological filters. This method will give better quantitative and qualitative results. Then the image is recovered using inverse 2D DWT. This technique can be applied in the fields of astronomy, satellite image processing etc. Keywords—image processing, wavelet transform