PURPOSE: To perform formation evaluation corresponding to human sense by subjecting a digital video signal to shading correction and binarization processing and dividing black parts in accordance with the size of particles and obtaining the total sum of respective areas.

CONSTITUTION: A synchronous processing part 10 of a picture signal processing device 5 gives a synchronizing signal 11 to a video camera 1 and a strobe 2, and the strobe 2 flashes synchronously with the signal 11, and the video camera 1 takes in a picture synchronously with it, and a still picture obtained in this manner is sent to an A/D converter 3 as an analog video signal 12 and is subjected to A/D conversion and is stored in a picture memory 4 as a digital picture signal 13. The device 5 subjects the signal 13 to shading correction by a shading correction processing part 7 and binarizes it with a luminance level by a binarization processing part 8 so that a prescribed white/black area ratio is obtained, and black parts are divided in accordance with the size of particles by an area calculation processing part 9, and the total sum of respective areas is obtained, and formation index is obtained by this part 9.