Quality metric that is computed from the entropy of all the pixels in the diffraction pattern. The pixels with a value of zero are ignored, so that the pixels removed from the Mask disc operation are ignored (Note the sum starts at 1 instead of 0).
where is the probability of having a pixel with the color i.
This quality index was used by Wright and Nowell  and Tao and Eades . They summarized this quality index as:
- Related to the compressability of information
- Describe the ‘business’ of an image
- Low entropy image: Low contrast, large number of pixels with same or similar values
- Similar results than Image quality
- Similar results than Pattern standard deviation
Example on NiCoCrAlY sample
Wright, S. I., & Nowell, M. M. (2006). EBSD image quality mapping. Microscopy Microanalysis, 12, 72-84.
Tao, X., & Eades, A. (2005). Errors, artifacts, and improvements in ebsd processing and mapping. Microscopy Microanalysis, 11, 79-87.