Abstract: This paper studied the evaluation methods of medical image quality to improve their reliability. Medical images arc obtained through using mathematical method to reconstruct them by compute, so the reliability of distortion image evaluation only very high, because the image during the process of imaging will be inevitably influenced by noise,making image being not uniform or distortion. The traditional medical image quality evaluation method only uses noise ratio to evaluate image quality, so the reliability of evaluation for image distortion is not high. To evaluate image quality,this paper put forward a gradient direction based evaluation method of medical image quality. It not only considers the image signal-to-noise ratio, but also combines the correlation of the pixels and human visual perception characteristics. It calculates gradient direction information used as the evaluation index, and can avoid the problem that evaluation reliability of the traditional method is not high to distortion image. The experiments show that the method can reflect the true image quality of visual perception, has high reliability evaluation.

Key words: Medical image, Quality evaluation, Gradient direction