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An Improved Algorithm of Congruent Matching Cells (CMC) Method for Firearm Evidence Identifications



D Ott, Jun-Feng Song, Wei Chu


The Congruent Matching Cells (CMC) method was invented at the National Institute of Standards and Technology (NIST) for firearm evidence identifications. The CMC method divides the entire image into small correlation cells and uses three sets of four identification parameters to identify correlated cell pairs originating from the same firearm. The CMC method was validated by identification tests using both 3D topography images and optical images captured from breech face impressions of 40 cartridge cases fired from pistols with 10 consecutively manufactured slides. In this paper, we discuss the processing of the cell correlations and propose an improved algorithm of CMC method which takes advantage of the cell correlations at a common initial phase angle and combines the forward and backward correlations to improve the identification accuracy. The improved algorithm is validated by 780 pairwise correlations for both the optical images and 3D topography images.
Journal of Research (NIST JRES) -


forensic science, ballistics identification, image processing, cartridge case, correlation cells, Congruent Matching Cells (CMC)


Ott, D. , Song, J. and Chu, W. (2015), An Improved Algorithm of Congruent Matching Cells (CMC) Method for Firearm Evidence Identifications, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 20, 2024)
Created April 28, 2015, Updated November 14, 2018