Two images from a sequence and their quality estimates are show above and below this text. Clearly the image above is less sharp than the image below and the quality-estimate (0.32 vs 0.36) is in agreement with this. The quality is estimated based on the information in the (spatial frequency) graphs you see right of the images. A sum of the values below the red line is calculated and the fraction that is located right of the green Quality-filter is the estimate. This is based on the fact that sharper/clearer image will show relatively higher amounts of fine (high spatial frequency) details than more blurred images. The position of the filter is crucial in proper estimating image quality, if the filter would be near to zero all the images would appear to have the same quality (~1). The NEXT PAGE shows more about setting this filter.