| 摘要 |
PURPOSE:To extract and record the contribution of a black plate picture to printed matter by recording infrared rays reflection at respective parts of four- color printed matter or a multicolor printed picture consisting of pictures of single or plural color printing ink and black ink. CONSTITUTION:Black generated by three primary color superposition has >=1.5 density on a normal densitometer and the difference to the density when while paper is measured is extremely large, but not so large at the measured value of a phototransistor having sensitivity at an infrared part. Black generated by black ink, on the other hand, absorbs infrared rays, so the difference in measured value from white paper is large and the same result with the measurement of the normal densitometer is obtained. Therefore, infrared reflection at respective parts of the polychromatic picture is recorded to extract and record the contribution of a black plate image to printed matter. |
