The paper describes a method for blind estimation of
sharpness and resolving power from a single image. These measures can
be used to characterize images in the context of the performance of
image analysis procedures. The method assumes the point spread
function (PSF) can be approximated by an anisotropic Gaussian. The
width Sigma of the PSF is determined by the ratio
Sigma_g/Sigma_g'
of the standard deviations of the intensity and
of its derivative at edges. The contrast sensitivity function (CSF)
is based on an optimal model for detecting straight edges between
homogeneous regions in noisy images. It depends on the signal to noise
ratio and is linear in the frequency. The method is applied to
artificial and real images proving that it gives valuable results.