A new image-extraction method of a debris cloud for hypervelocity impact is proposed. The method can capture the accurate shape of the debris cloud from the image shot by a high-speed camera. The measurement method for the shape of the debris cloud in the image has not been founded so far. It is important to establish a method to obtain the cloud shape considering the major influence that the cloud exerts on the pressure wall. We apply the classification error rate for extracting the debris cloud from the image shot by a high-speed camera. Specifically, the normalized histogram of a background is assumed to be gamma distribution in order to fit the histogram with the reality. Our method excels conventional methods in a measurement accuracy of the shape of the debris cloud.
