Once refinement of the crystal orientation for one image is complete a final integration of the spots is performed using profile fitting [27]. A calculated spot profile for every reflection is evaluated by averaging the observed profiles of other strong reflections within a specified radius on the image. A constant symmetric background is calculated for the reflection and the predicted profile is then normalised such that , where the sum is over all the pixels within the profile. The experimentally measured intensity in the th pixel is defined as

such that the constant is a measure of the fitted integrated intensity calculated with knowledge of only , and for any one pixel. The variance of is defined as [38]

The final profile fitted intensity is defined as the weighted average of all the individual intensity estimates from each pixel:

Fri Oct 7 15:42:16 MET 1994