The Study of Image Definition Evaluation Function Based on Wavelet Filter

The auto-focus method based on digital image processing results from the innovation of the traditional auto-focus method. Generally speaking, the traditional auto-focus method needs extra focus equipment and can be disturbed easily by environment factors. So the application of the traditional auto- focus method is limited hugely. The auto-focus method based on digital image processing is usually achieved by image definition evaluation functions. The paper studies the structure of two-dimension minimum isotropy wavelet filters and propounds the image definition evaluation based on a wavelet filter. In the paper, the evaluation function based on the wavelet filter is compared with the evaluation function based on the Laplacian operator by using the auto-focus system of a microscope. The experiment results indicate that the auto-focus algorithm based on the isotropy wavelet filter has good performance.