Algorithm Research Of Remote Sensing Image Quality Criterion On Focusing And Data Compression

Image clarity evaluation function is the key of automatic focusing camera. For the needs of auto-focus in a space camera, we used the optimal discrete cosine transform(DCT) coefficients as evaluation methods with defocused image clarity, and analysed correlation with the modulation transfer function(MTF) of the defocus images. And results show that the evaluation method based on the discrete cosine transform(DCT) obtained similar results of MTF, and it will be applied to automatic focusing system.In addition, considering the transmission capability of remote satellites,data needs to be stored in the transmission process with compression, so the assessment of space image compression quality is very important. A space visible camera can achieve image compression with ADV212& JPEG2000, structural similarity algorithm(SSIM) for image different compression ratios were image quality evaluation, experimental results show considerable results of evaluation of the algorithm can be obtained, value is almost equal with peak signal to noise ratio, it have engineering application value.In this project,the main work as follows:Firstly, Survey research image clarity and image quality assessment algorithms over domestic and foreign, studied the auto-focusing methods, image compression coding theory, the factors of decline in image quality, various image evaluation algorithm for analysis.Secondly, Automatic focusing research methods, there are defocus depth method and focus depth method as automatic focusing methods based on image processing, the optimal discrete cosine transform(DCT) coefficients was used to evaluate image clarity. In order to get reliable results, we also used the hypotenuse edge method to obtain MTF value of compressed images at the Nyquist frequency.Thirdly, For a visible camera space using ADV212 as image compression chip, the thesis used structural similarity algorithm(SSIM) to do the image quality evaluation for the images with different compressed ratios.Innovative ideas are as follows:(1) The optimal discrete cosine transform(DCT) coefficients was used as evaluation methods, and we analysed correlation with the results of the evaluation with MTF.(2) Structural similarity algorithm was used to do image quality evaluation for compressed image with different ratios from ADV212.