Pattern entropyΒΆ

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).

Q = -\sum\limits_{i=1}^{255}{P_i\ln{P_i}}

where P_i is the probability of having a pixel with the color i.

This quality index was used by Wright and Nowell [1] and Tao and Eades [2]. 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

  1. Wright, S. I., & Nowell, M. M. (2006). EBSD image quality mapping. Microscopy Microanalysis, 12, 72-84.
  2. Tao, X., & Eades, A. (2005). Errors, artifacts, and improvements in ebsd processing and mapping. Microscopy Microanalysis, 11, 79-87.