ABSTRACT This report focus on the problem of applying subjective image quality criteria, when designing image enhancement methods. A review is given on image quality measures and on the use of perceptual factors in image restoration. A variation of the wienerfilter is proposed, called the fixed signal-to-noise ratio filter. One property of this filter is that the output signal-to-noise ratio is constant. An iterative method of restoration, the projection method, has been investigated. Using measurements of blur and noise in the image after each iteration, it is possible to decide when to stop iterating. Combining adaptive noise reduction methods with the projection method makes an efficient procedure for image enhancement, where it is easy to incorporate information on visual perception.