Image Evaluation based on Fast Wavelet Transform

Accurate and efficient image evaluation function is the foundation for auto-focusing system based on digital image processing.Based on comparison of image evaluation algorithm on time domain and frequency domain with Matlab Image-processing Toolbox,a focusing evaluation algorithm based on Fast Discrete Wavelet Transform(FDWT) is proposed,and the simulation with Matlab show that the proposed algorithm is quite reliable and sensitive.The comparison of this algorithm with other focusing evaluation algorithms,such as Edge Detection Algorithm(including Robert,Sobel,Prewitt and Laplace) and Discrete Cosine Transform(DCT) is also done,and it shows that FDWT algorithm is high in computing speed,and could evaluate the digital image accurately and effectively.