This study explains the comparison of techniques for cropping existing in Matlab for graylevel images on periapical radiographs of human teeth. Some cropping techniques in Matlab are rectangular crop, square crop, circular crop, ellipse crop, polygon crop. This research will explain how each existing cropping technique will give different results based on their respective shapes. So that eventually will produce the most appropriate cropping techniques among several existing cropping techniques in mathlab. The five cropping techniques that have been mentioned here where the four existing cropping techniques namely rectangular crop, square crop, circular crop, ellipse crop still carry other objects that are not needed in research, so it is not appropriate to be used for research objects that have irregular shapes. Appropriate cropping technique is polygon cropping because it is able to identify research objects that have irregular shapes.