| 摘要 |
The present invention has a camera (12) for capturing an image of the surface of a fastener element (24) of a slide fastener (20), and an illumination device (14) for illuminating the fastener element (24). A plurality of control factors which affect the image captured by the camera (12) are selected, and an image of each of a plurality of fastener elements (24) is captured simultaneously in a plurality of conditions of the control factors. Color image data in an individual unit region of each of the fastener elements (24) are extracted for a plurality of color images captured of the plurality of fastener elements (24) by the camera (12). Luminance characteristic values for each of the three primary colors of light are obtained for each pixel of the color image data of the unit regions of the fastener elements (24). An error variance in the color of a fastener element (24) is calculated on the basis of the computed characteristic values for the three primary colors of light. The SN ratio and sensitivity of the image data of each fastener element (24) is computed for each set condition of the control factors on the basis of the obtained error variance, and the set condition of a control factor for which the SN ratio and sensitivity values are relatively large is selected from among the computed SN ratios and sensitivities. |
