Measurement of visual characteristics of paper

摘要

A paper web formation measurement system provides on-line measurement and control of visual properties of a moving web of paper. The measurement system includes an image acquisition system for capturing images of the moving web, and an image analysis system for analyzing captured images. The image acquisition system includes a strobe lighting system for backlighting the moving web and a charge injection device (CID) camera for capturing light transmitted through the web to form an image of the web in non-standard (non-RS-170), full frame format. Captured images are digitized by the image analysis system to 256 graylevel and analyzed to produce a mathematical formation index representing visual properties of the web. The mathematical formation index, which is derived from a graylevel distribution histogram, is presented to paper production personnel to enable on-line adjustment of process variables to maximize paper quality. The image analysis system is also configured to ascertain the distribution of flocs and voids within the image. The mathematical formation index may be adjusted to reflect the distribution of flocs and voids within the web.