Image analysis – Histogram processing – For setting a threshold
Patent
1983-03-22
1985-12-24
Boudreau, Leo H.
Image analysis
Histogram processing
For setting a threshold
356 71, 356394, 358106, 364551, 382 34, 382 45, G06K 900, G06K 500
Patent
active
045611033
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a method of accurately inspecting prints which are being run in a rotary press or the like, in order to determine whether or not the prints are acceptable, and to an apparatus for practicing the method.
2. Background Art
In general, prints must be finished to a considerably high degree. Accordingly, an inspecting method sufficiently high in reliablity must be employed in inspecting such prints.
In a rotary press or the like, prints are being run at high speed. Accordingly, if a visual inspection method is employed, it is impossible to inspect the prints in real time.
In order to overcome the difficulty, an inspecting method has been proposed in which the picture pattern of a print being run is detected by a one-dimensional image sensor camera or the like to provide video signals, and the video signals thus provided, being handled as analog data, are compared with the reference voltage to determine whether or not the print is acceptable, or binary-coded with a predetermined threshold value thereby to determine the acceptability of the print.
The above-described method utilizing the analog video signals may detect defects on a blank roll stock with high accuracy; however, it is disadvantageous in that, in the case where the density varies widely as in the case of the picture pattern on a print, the accuracy for determining whether or not the print is acceptable is not sufficient.
In order to overcome this drawback, a method has been proposed in which the video signals are digitalized so that the video signals of the entire picture pattern of a print under inspection can be stored, video signals obtained from a reference print are stored as reference data, and video signals obtained from a print under inspection are employed as inspection data, so that the inspection data is compared with the reference data which is read out for every picture element, to determine whether or not the print is acceptable.
The method is much higher in inspection accuracy than the visual inspection method or the analog inspection method.
An object of this invention is to improve a conventional print inspection apparatus of digitalization type, thereby to provide a print inspecting apparatus in which the accuracy is much higher, an effective masking function is readily provided, and the operation is stable even when the state of prints is changed.
DISCLOSURE OF THE INVENTION
The specific feature of the invention resides in that image data read out of a reference print is written in a memory while image data read out of a print under inspection is employed as inspection data, and when the inspection data is compared with the reference data, for instance, for every picture element to determine whether or not the print is acceptable, the reference data is rewritten by detecting not only the image data but also the print running speed or the position of the picture pattern in the direction of width.
The specific feature of the invention resides further in that, in comparing the detection data with the reference data for every picture element for instance, the comparison level is optionally set up for every picture element.
The specific feature of the invention resides further in that the data comparison is carred out not only for every picture element, but also for the sum of picture elements over the entire picture pattern and for the sum of picture elements arranged linearly in the print running direction, and the results of comparison are generally judged to determine whether or not the print is acceptable.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory diagram showing theoretically one example of a print inspecting method according to a digitalization system.
FIG. 2 is an explanatory diagram outlining a reference data memory.
FIG. 3 is a block diagram showing the entire arrangement of one example of a print inspecting apparatus according to this invention.
FIG. 4 is a circuit diagram showing one example of a running postion signal input circuit.
FIG. 5 is
REFERENCES:
patent: 3645626 (1972-02-01), Druschel
patent: 3710323 (1973-01-01), Andrews et al.
patent: 3883737 (1975-05-01), Throssell et al.
patent: 4197584 (1980-04-01), Blazek
patent: 4319270 (1982-03-01), Kimura et al.
Crawford, "Pictorial Information Disector and Analyzer System (PIDAS)", IBM Tech. Disclosure Bulletin, vol. 15, No. 1, Jun. 1972, pp. 61-62.
Harima Hiroshi
Horiguchi Satoru
Boudreau Leo H.
Dai Nippon Insatsu Kabushiki Kaisha
LandOfFree
Print inspecting method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Print inspecting method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Print inspecting method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1483875