Image comparison method

Abstract

To accurately compare lines of graphs respectively drawn in a plurality of images.SOLUTION: A method for comparing lines of colored graphs respectively drawn in a plurality of images includes: a first step S10 of performing saturation extraction on each image; a third step S30 of extracting a graph region in which a line of a graph is drawn in an image; and a fourth step S40 of changing scale of the graph region so that sizes of respective extracted graph regions matches and comparing the lines of graphs drawn in the respective graph regions by superimposing the respective graph regions of which the sizes are matched.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for comparing images.

Background Art

[0002] For example, Patent Document 1 describes a method for comparing whether two images are similar.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the images included in technical information such as regulations, there may be lines of graphs drawn. Here, such graph lines may differ from country to country or may be changed due to revisions of regulations.

[0005] Therefore, there may be a case of comparing the graph lines drawn in a plurality of images and determining whether they match. However, such images have not only graph lines but also scales, characters, etc. drawn. Therefore, when comparing a plurality of images to determine whether the graph lines drawn in those images are the same, even if the graph lines are the same, if the scales, characters, etc. are different, there is a risk of being determined as different images from each other. Therefore, it is desired to accurately compare the graph lines drawn in a plurality of images.

Means for Solving the Problems

[0006] The method for comparing images that solves the above problems is a method for comparing the lines of graphs depicted and colored in a plurality of images. This comparison method includes a step of performing saturation extraction on each image, a step of extracting a graph region in which the lines of the graph are depicted in the image, a step of changing the scale of the graph region so that the sizes of the extracted graph regions match, and a step of overlapping the graph regions with the same size and comparing the lines of the graph depicted in each graph region.

[0007] The lines of graphs depicted in images included in technical information such as regulations are often colored. On the other hand, information other than the lines of the graph, such as scales and characters, is often drawn in white or black and is achromatic. Therefore, in the same method, by performing saturation extraction on the image, the colored lines of the graph are extracted from the image. Accordingly, it is possible to compare only the lines of the graph depicted in each image without being affected by the scales and characters depicted in the image. Therefore, it becomes possible to accurately compare the lines of the graph depicted in a plurality of images.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0009] Hereinafter, one embodiment in which the method for comparing images is embodied will be described. <Regarding the Configuration> As shown in FIG. 1, an execution device 100 that implements an image comparison method includes a central processing unit (hereinafter referred to as CPU) 110, a memory 120 in which control programs and data are stored, and the like. Then, the execution device 100 executes various processes by the CPU 110 executing the programs stored in the memory 120. Examples of the execution device 100 include a personal computer and a server.

[0010] An image display device 200 is connected to the execution device 100. The image display device 200 displays the results of each process executed by the execution device 100. <Image Comparison Method> FIG. 2 shows the steps of the image comparison method performed by the execution device 100.

[0011] <First Step> First, as a first step S10, the execution device 100 executes a saturation extraction process. The saturation extraction process is a process of extracting the colored portions in the image, that is, the portions drawn in colors other than achromatic colors such as white and black.

[0012] When starting the first step S10, the execution device 100 first reads the first image 10 and the second image 20. Both the first image 10 and the second image 20 are images included in technical information such as regulations, and are drawn with colored graph lines, uncolored scales, and characters. Hereinafter, the graph line drawn in the first image 10 is referred to as the first graph line Ga, and the graph line drawn in the second image 20 is referred to as the second graph line Gb.

[0013] Incidentally, as an example of the first image 10, there is a time change of vehicle speed defined by the previous regulations when testing the exhaust performance of a vehicle. As an example of the second image 20, there is a time change of vehicle speed defined by the revised regulations when testing the exhaust performance of a vehicle.

[0014] Then, the execution device 100 generates a first image 10a in which the background is black and only the first graph line Ga that was colored is drawn, by performing a saturation extraction process on the loaded first image 10. Note that the color of the first graph line Ga is converted to gray by this saturation extraction process. Similarly, the execution device 100 generates a second image 20a in which the background is black and only the second graph line Gb that was colored is drawn, by performing a saturation extraction process on the loaded second image 20. Note that the color of the second graph line Gb is converted to gray by this saturation extraction process. Next, the execution device 100 executes the second step S20.

[0015] <Second Step> When the execution device 100 starts the second step S20, it generates a first image 10b in which the color of the first graph line Ga is converted from gray to white, by performing a binarization process on the first image 10a. Similarly, the execution device 100 generates a second image 20b in which the color of the second graph line Gb is converted from gray to white, by performing a binarization process on the second image 20a. Next, the execution device 100 executes the third step S30.

[0016] <Third Step> When the execution device 100 starts the third step S30, it generates a first graph region image 10c by extracting the region where the first graph line Ga is drawn from the first image 10b, by performing a graph region extraction process on the first image 10b.

[0017] The graph region extraction process is executed, for example, as follows. First, when the first image 10b is placed in the XY coordinate system, let the minimum value of the first graph line Ga in the X-axis direction be Xmin and the maximum value be Xmax. Also, let the minimum value of the first graph line Ga in the Y-axis direction be Ymin and the maximum value be Ymax. Then, the first graph region image 10c is generated by extracting the rectangular region surrounded by the four points (Xmin, Ymin), (Xmin, Ymax), (Xmax, Ymin), and (Xmax, Ymax) from the first image 10b.

[0018] Similarly, the execution device 100 generates a second graph region image 20c by executing a graph region extraction process on the second image 20b to extract the region in which the second graph line Gb is drawn from the second image 20b. Next, the execution device 100 executes the fourth step S40.

[0019] <Fourth Step> When starting the fourth step S40, the execution device 100 first executes a scale adjustment process. The scale adjustment process is a process of changing the scale of the graph region image so that the sizes of the first graph region image 10c and the second graph region image 20c match.

[0020] Next, the execution device 100 executes an overlapping process. The overlapping process is a process of overlapping the first graph region image 10c and the second graph region image 20c with matching sizes and comparing whether the first graph line Ga and the second graph line Gb match. Note that the matching process for comparing such images may be performed by a well-known method.

[0021] The execution device 100 displays the comparison result of whether the first graph line Ga and the second graph line Gb match on the image display device 200 in an appropriate manner. <Operation and Effect> The operation and effect of this embodiment will be described.

[0022] (1) The lines of the graphs drawn in the images included in technical information such as regulations are often colored. On the other hand, information other than the graph lines, such as scales and characters, is often drawn in white or black and is achromatic. Therefore, in this embodiment, by performing a chroma extraction process on the image, the colored graph lines are extracted from the image. Accordingly, it is possible to compare only the graph lines drawn in each image without being affected by the scales and characters drawn in the image. Therefore, it becomes possible to accurately compare the graph lines drawn in a plurality of images.

[0023] (2) Since the lines of the graphs drawn in the plurality of images can be accurately compared, the accuracy of automatic determination when comparing the lines of the graphs using the execution device 100 is also improved.

[0024] <Modified Example> Note that the above-described embodiment can be modified and implemented as follows. The above-described embodiment and the following modified examples can be implemented in combination with each other within a range that is not technically contradictory.

[0025] · Although two images were compared, three or more images may be compared. · The second step S20 may be omitted. · In the saturation extraction process of the first step S10, the first image 10a and the second image 20a in which the backgrounds of the first image 10 and the second image 20 are converted to black were generated. However, the first image 10a and the second image 20a in which the backgrounds of the first image 10 and the second image 20 are converted to white may be generated. In the case of this modified example, in the binarization process of the second step S20, the colors of both the first graph line Ga and the second graph line Gb may be converted from gray to black to generate the first image 10b and the second image 20b.

[0026] · In the fourth step S40, the scale adjustment process and the superposition process were executed. Alternatively, in the fourth step S40, the scale adjustment process may be executed. Then, the superposition process may be executed as the next fifth step S50.

Explanation of Reference Numerals

[0027] 100…Execution device 200…Image display device

Claims

【Claim 1】 A method for comparing lines of a graph depicted and colored in a plurality of images, comprising: a step of performing chroma extraction for each image; a step of extracting a graph area in which the lines of the graph are depicted in the image; a step of changing the scale of the graph area so that the sizes of the extracted graph areas match; a step of overlapping the graph areas with matching sizes and comparing the lines of the graph depicted in each graph area. An image comparison method.

Images