Process and apparatus for the colorimetric analysis of printed material
First Claim
1. A process for the colorimetric analysis of a printed color measuring strip by means of a scanning densitometer, the measuring head of which is guided along the measuring strip to be analyzed, thereby generating a plurality of color density values representing the color properties of the measuring strip, with said color density values being evaluated automatically for the recognition of the measuring fields of the color measuring strip and for the correlation of the color density values with the measuring fields, the process including the steps of guiding the measuring head along the color measuring strip in a recognition run, thereby scanning each measuring field in a multitude of scanning points so as to produce a multitude of color density values and determining from this multitude of color density values measuring positions suitable for the measuring process itself and further processing essentially only color density values originating in the determined measuring positions.
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Accused Products
Abstract
On a measuring table (1), a bridge (2) extends over a printed sheet (5) to be measured. A measuring carriage (3) carrying a three color-simultaneous measuring head is arranged on the bridge (2) for linear movement in a back-and-forth manner along a desired path on the printed sheet. For control of the movement of the measuring head during measuring runs and for the evaluation of the measured data, a computer (7) with an integrated image display terminal and a processor system (6) controlled by the computer, is provided with the necessary interfaces. The analysis of a color measuring strip (MS) located along the desired path on the printed sheet is effected in two phases. In a first, so-called recognition run the measuring strip is scanned stepwise with high resolution in all three color channels, for the purpose of an analysis of its configuration. By means of flat locations in the density variations, effective positions (e.g., the centers) in the measuring fields are determined as possible measuring positions for subsequent measuring runs. During the measuring runs the measuring strip is measured only at the measuring positions determined during the recognition and the measured data obtained in this manner are transmitted for processing and/or display to the computer (7). By the division of the measurements into a recognition and a measuring run, coupled with the determination of measuring positions by means of flat locations in the density variations, a practically completely automatic evaluation of the color measuring strips independently of their configuration and without the need of prior knowledge of the strips by the apparatus, is rendered possible.
160 Citations
31 Claims
- 1. A process for the colorimetric analysis of a printed color measuring strip by means of a scanning densitometer, the measuring head of which is guided along the measuring strip to be analyzed, thereby generating a plurality of color density values representing the color properties of the measuring strip, with said color density values being evaluated automatically for the recognition of the measuring fields of the color measuring strip and for the correlation of the color density values with the measuring fields, the process including the steps of guiding the measuring head along the color measuring strip in a recognition run, thereby scanning each measuring field in a multitude of scanning points so as to produce a multitude of color density values and determining from this multitude of color density values measuring positions suitable for the measuring process itself and further processing essentially only color density values originating in the determined measuring positions.
- 4. The process for the colorimetric analysis of a printed color measuring strip by means of a scanning densitometer, the measuring head of which is guided along the measuring strip to be analyzed, thereby generating a plurality of color density values representing the color properties of the measuring strip, with said color density values being evaluated automatically for the recognition of the measuring fields of the color measuring strip and the correlation of the color density values with the measuring fields, the process including the steps of determining for each scanning location the color density values of the color measuring strip and analyzing their variations and, by means of this analysis determining scanning locations along the measuring strip which are located within flat sections of the variation of the color density values, wherein only color density values originating in measuring positions determined in this manner are used for further processing and display.
- 12. Apparatus for the colorimetric analysis of a printed color measuring strip on a printed sheet, with a support surface for the sheet and a measuring head, guided on a bridge extending over the support surface and movable back and forth on said bridge by a motor, said head being designed for the photoelectric scanning of the color measuring strip on the printed sheet, and with an electronic control means for controlling the movements and measuring runs of the measuring head and for evaluating the measuring data generated by said measuring head, said control means including means for guiding the measuring head through a recognition run in incremental advance steps along the measuring strip wherein, after each advance step, the color density values of the color measuring strip are measured for each of the three base colors, and means for determining the configuration of the color measuring strip and locating and storing the measuring positions from which the measuring data of interest for the evaluation of the printed sheet are to be taken in response to said measured color density values.
- 30. Process for the colorimetric analysis of a printed color measuring strip by means of a scanning densitometer, the measuring head whereof is guided mechanically along the measuring strip to be analyzed, thereby generating a plurality of color density values representing the color properties of the measuring strip, with said color density values being evaluated automatically for the recognition of the measuring fields of the color measuring strip and for the correlation of the color density values with the measuring fields, the process including the step of determining the structure of the color measuring strip and the measuring positions suitable for the measurement itself by determining with the measuring head, for each scanning location, the densities of the color measuring strip in three base colors, and determining the measuring positions for the subsequent measuring runs as those locations along the measuring strip whereat the three color density variations have flat sections.
Specification