Per Image Analysis Plot

‚ÄčPer image analysis
The per image analysis plot shows:

  • Number of total spots found (yellow)
  • Number of those spots which can identiifed as Bragg diffraction (blue)
  • An estimate of resolution (red)

The axes are:

  • Lower x: Number of Images
  • Upper x: Degrees (including the starting angle)
  • Left y: Spots identified
  • Right y: Resolution estimate

The plot can be clicked to open it in a modal window:

per image analysis

Upto 250 images evenly spaced across the dataset are displayed.

The per image analysis plot can be used to make quick assessments of diffraction to aid decision on whether the crystal should be re-collect due to incorrect alignment, or if a batch of crystals are poorly difracting.

Per image analysis -1

If -1 is shown for the resolution estimate, it could not be determined for that image. When this shows for a few images only it may be a a sign of relatively few spots per image. When shown for all iamges it may show more signficant issues with the underlying data, such as a lack of diffraction in the below example:

per image analysis no diffraction

Rotation of the sample out of the beam is usually shown by an indicative drop and then return of spots:

out of beam

If there is a consitent dall off of spots (a downward slope) throughout the full rotation of the crystal it indicate intensity decay for radiation damge to the crystal. This can also be assessed with the radiation damage plot.
Downward PIA radiaiton
The calculations are made usings DIALS.

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