Patent ID: 8289386

Claim:
A sheet-like product inspecting method, comprising: providing an inspection plate having a light color region and a dark color region and a color camera capable of picking up images of three lines of R, G and B; acquiring respective R, G and B image data of the R, G and B lines for a sheet-like product after being washed, which is passed over the inspection plate; synthesizing respective images of the R, G and B lines to obtain a synthesized image of the sheet-like product in which a color of a defective portion is emphasized; detecting a color changed region in the synthesized image; and determining a defect type depending on whether a color of the color changed region falls within a certain range of setting parameter, which is stored in advance for each of defect types including dirt and a tear; wherein the images of two among the R, G and B lines are picked up at positions in one of the color regions, and the image of the other one line is picked up at a position in the other color region.