An Image Enhancement Algorithm for River Main-Stream Based on Remote Sensing Data with Wavelet Transform

In the lower Yellow River, main-stream changes frequently for quickly change of channel sediment erosion and deposition, so it has a great significant to monitor its variation with remote sensing data during flood control decision-making. However, water spectral difference is weak and unsteady between main-stream area and other flow area in river, which leads main-stream´s feature unclear and difficult to be recognized on image and image enhancement becomes an essential step before doing main-stream detection. In this paper, a wavelet enchantment algorithm was proposed to prominent main-stream information through combing wavelet spatial-frequency characteristic and a spatial gradient operator. The gradient operator was mainly used to calculate wavelet coefficient gain matrix to construct the wavelet transform inverse-coefficients. The experiment results show that main-stream information was enhanced evidently as well as noise decreased, and the image preprocessing by proposed algorithm can meet the requirement for main-stream detection.