The present invention relates generally to synchronizing image data, and, more particularly, selecting related images from a plurality of different camera positions.
When an operator of several cameras films an event, for example, to analyze a paper web, and finds an interesting object, by utilizing synchronization, he will be able to see the same area in the paper web as it passes other camera positions. This type of synchronization has long been a characteristic of the Applicant's operations. However, its use involves certain problems or deficiencies. Due to the high speed and stretching of the web, it is not possible for synchronization to be so accurate as to necessarily show the corresponding area in the web in the new position shown by the synchronization. If there is, for example, an interruption at the dry end of the machine and the operator of the monitoring system searches for the same area in the web at the wet end of the machine, the operator cannot be absolutely certain whether the object is located in the area of the video recording displayed as a result of synchronization, in which case the operator is likely to discontinue the search.
The present invention is provided for improved synchronizing of image data obtained from process monitoring cameras, wherein
An exemplary embodiment of the invention is described in the following with reference to the accompany drawings in which:
The aim of the present invention is to provide an improved synchronization method, so that the operator will know for certain that he will arrive automatically in the middle of the visualized area, inside which the desired same area of the web can be found. The idea is, therefore, to compel the operator to go through an area of sequential images of a size that can be parameterized. In such a case, the corresponding area in the web in different camera positions will be found more reliably and easily.
The general structure and operation of the system are first described before disclosing the manner according to the invention for visualizing the area of sequential images to be synchronized to the operator.
In the flow chart shown in
The system comprises several video cameras 1 for imaging the various positions of the process being monitored. Each camera is provided with its own digital image processor 2 for storing digital image data per camera. The signal processors 2 are used for analyzing each camera-specific image data item so as to provide image variation data based on the level of variation in a plurality of sequential images. From the signal processors 2 the said image data and image variation data are transmitted to an analyzing computer 15 which has a display 11.
The images stored at the different camera positions can be selected for analysis by means of selector icons 7. The image variation graph 8 corresponding to the image variation data of images preceding and following the image to be analyzed is displayed at the bottom of the screen 11. A floating arrow designated by reference numeral 9 indicates the point on the image variation graph 8 at which the image 6 displayed is located. The floating arrow 9 can be used for selecting an image at any point on the graph 8 for display. The image data 2d1-2dn stored from each camera position 1−n may encompass several hundred images. Depending on the process, the image data in store at each time may have a duration ranging from a few seconds to several minutes, and the storage may function on the FIFO (first in first out) principle.
Since each image variation graph 8 shown at the bottom of the screen 11 is prepared of image material from each respective camera position, the image variation graphs of the different camera positions can be standardized so as to be comparable, and be compared with each other, whereby the image variation graph representing the highest-level variation and the image data of the camera position corresponding to it can be selected automatically for displaying on the analyzing window of the screen 11. For the purpose of this automation, the system is provided with standardizing means 3 for standardizing the output levels of the image variation data of the different camera positions to be mutually comparable. A comparison between the standardized image variation levels of the different camera positions is performed by means of comparator means 4. Selector means 5 receive image data from the different camera positions and select, under the control of the comparator means 4, the image data 2d1-2dn representing the highest-level variation and the corresponding image variation graph 8 to be displayed on the screen 11. Image 6 is one of a multitude of images included in the image data. The graph 8 and the floating indicator 9 can be used for examining those very images 6 associated with the area of the highest-level image variation. The image 6 on the screen 11 may represent, for example, a hole formed in a paper web.
The automated selection of the image 6, as described above, is obviously optional, meaning that the operator may, if he so desires, select image data 2d1-2dn from any camera position for analysis. However, it is often useful for the operator to know at the very beginning of analysis which camera position produced the highest-level image variation, in which case the analysis can be started from this particular camera position.
The operator's data processing means 15 comprise synchronization means 12, 13, 14 by means of which images depicting the same area in the web can be sought automatically from the image data of different camera positions. When the synchronization option 12 is displayed on the screen 11, the synchronization unit 13 controls the image data selection unit 5 in such a way that the selection of a camera position by means of the selector icons 7 automatically produces on the screen 11 the image 6 which corresponds to the same area in the paper web as the image 6 of the previous camera position. For this purpose the synchronization unit 13 requires certain parameters 14, which include at least web speed and the distances between the cameras 1. The synchronization unit 13 is also given a time of occurrence 2t at which an interesting object was observed in the image field of a camera position, the web area corresponding to which having to be analyzed from the different camera positions.
Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.
Number | Date | Country | Kind |
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990428 | Mar 1999 | FI | national |
Number | Name | Date | Kind |
---|---|---|---|
4922337 | Hunt et al. | May 1990 | A |
4992866 | Morgan | Feb 1991 | A |
5239376 | Dittmann et al. | Aug 1993 | A |
5717456 | Rudt et al. | Feb 1998 | A |
5767980 | Wang et al. | Jun 1998 | A |
5956081 | Katz et al. | Sep 1999 | A |
5995140 | Cooper et al. | Nov 1999 | A |
6359647 | Sengupta et al. | Mar 2002 | B1 |
Number | Date | Country |
---|---|---|
0 366 235 | May 1990 | EP |
0837323 | Apr 1998 | EP |
0 837 323 | Apr 1998 | EP |
0 847 201 | Jun 1998 | EP |
973611 | Nov 1997 | FI |