KR20070121216A - Camera test unit and camera inspection method using the same - Google Patents

Abstract

A camera test unit and a camera inspecting method using the same are provided to test a camera by using a single camera test unit, thereby more quickly performing a test work. A camera test unit(100) comprises test units(102,104,106) by focal distances and a line pair chart. The test units by focal distances are integrally prepared so as to test photographing performance integrally by different focal distances. The line pair chart has different line interval and line width and installed in each test unit by focal distance so as to inspect a focus and a resolution according to the number of pixels from a low pixel to a high pixel.

Description

CAMERA TEST UNIT AND CAMERA INSPECTION METHOD USING THE SAME}

1 is a view showing a camera test unit according to an embodiment of the present invention.

2A to 2C are views illustrating a wide-angle test unit, a telephoto test unit, and a macro test unit constituting a camera test unit.

FIG. 3 is a diagram illustrating automatic resolution inspection using the camera test unit shown in FIG. 1. FIG.

4 is a view showing an automatic color reproducibility test using the camera test unit shown in FIG.

FIG. 5 is a diagram illustrating an automatic white balance inspection using the camera test unit shown in FIG. 1. FIG.

FIG. 6 is a diagram illustrating automatic distortion inspection and correction using the camera test unit shown in FIG. 1. FIG.

7 is a diagram illustrating a configuration of a camera test system using a camera test unit according to an exemplary embodiment of the present invention.

8 is a flowchart illustrating a camera inspection method for testing the performance of a camera using the camera test unit shown in FIG. 1.

* Description of the symbols for the main parts of the drawings

100: camera test unit

102: wide angle test unit

104: test unit for telephoto

106: test unit for macro

202a, 202b, 602: Mark for pattern alignment

204 gray level bar

206: Color Bars

208a, 208b: Line Pair Chart

702: camera

704: Inspector

706: computer system

The present invention relates to a camera test unit and a camera inspection method using the same, and more particularly, to a camera test unit for testing the performance of a digital camera module mounted on a digital camera or a mobile communication terminal and the like and a camera inspection method using the same.

When inspecting the performance of video equipment such as cameras, the inspector performs a visual inspection. In other words, after individually testing each component such as a lens and a sensor, the inspector visually inspects whether the finished product operates normally.

However, when visually confirming the result of an imaging device with the naked eye, there is a disadvantage in that it is difficult to accurately evaluate the performance of the product due to the difference in visual acuity or subjective judgment criteria for each monitor. In other words, since it is subjective to judge whether each inspector focuses or expresses color, the reliability of the test result is low because the exact performance value cannot be obtained.

In addition, the conventional inspection method has a disadvantage in that the inspection speed is delayed and the work efficiency is lowered because the inspection process using a separate test unit is performed for each pixel number and the shooting mode when inspecting the performance of an imaging device such as a camera. have.

A camera test unit and a camera inspection method using the same according to the present invention have an object of enabling a test operation to be performed more quickly by testing a camera using a single camera test unit.

In addition, the object of the present invention is to enable fast, objective and accurate camera testing by automatically analyzing the image of the above-described test unit through a test program on a computer system.

Camera test unit according to the present invention for this purpose, a plurality of focal length test units are provided integrally to test a plurality of different shooting distance-specific shooting performance; It includes a line pair chart with different line spacing and line width, which is provided for each test unit for each focal length, so that the focus and resolution can be inspected by the number of pixels from the low pixel to the high pixel.

In addition, the above-described focal length-specific test units include a wide-angle test unit, a telephoto test unit, and a macro test unit.

In addition, the above-mentioned wide-angle test unit includes a color bar for color inspection; It further includes a brightness level gray level bar.

In addition, each of the above-mentioned wide-angle test unit, telephoto test unit, and macro test unit is provided with a mark for pattern alignment for distortion aberration inspection of the camera and position compensation of the camera test unit; The size of the pattern alignment mark provided in the wide-angle test unit is relatively larger than the pattern alignment mark provided in the telephoto test unit and the macro test unit.

In addition, the above-described macro test unit shares a part of the line pair chart and the pattern alignment mark of the wide-angle test unit and the telephoto test unit.

In addition, the narrowest line width of the above-mentioned line pair chart is a micrometer (micrometer) unit.

A camera inspection method using a camera test unit according to the present invention for the above-mentioned object, to capture a single camera test unit to obtain an image; Transmits an image to a computer system 706 in which a camera test program is installed and operated; An image transmitted to the computer system 706 is automatically analyzed through a camera test program and the inspection result is displayed on the monitor; The inspector 704 checks the inspection result displayed on the monitor of the computer system 706 to determine whether the camera 702 is ok.

In addition, the above-described camera test unit; A plurality of focal length test units integrally provided to collectively test a plurality of different focal length photographing performances; It includes a line pair chart with different line spacing and line width, which is provided for each test unit for each focal length, so that the focus and resolution can be inspected by the number of pixels from the low pixel to the high pixel.

In addition, the tests performed automatically on the computer system described above; It includes automatic resolution check, automatic color reproducibility check, automatic white balance check, automatic distortion check and correction, and pixel defect check.

When described with reference to Figures 1 to 8 a preferred embodiment of the present invention made as described above. 1 is a diagram illustrating a camera test unit according to an exemplary embodiment of the present invention, wherein a camera test unit (that is, an apparatus provided with patterns for testing a camera's performance) according to an exemplary embodiment of the present disclosure may have various focal lengths different from each other. Unit test units for testing the camera's performance on a per-pixel (i.e., viewing angle) and pixel-by-pixel basis are all provided in a single camera test unit. As shown in FIG. 1, the camera test unit 100 is provided with a wide-angle test unit 102, a telephoto test unit 104, and a macro test unit 106. The wide-angle test unit 102 is for testing the performance of the camera in a shooting condition with a short focal length and a wide viewing angle, and the telephoto test unit 104 or the macro test unit 106 is used to obtain a large image at a wide angle. Have a relatively larger size than). Telephoto test unit 104 is for testing the performance of the camera in the shooting conditions that can be taken by magnifying the long-distance subject instead of a narrow viewing angle due to the long focal length, the wide-angle test unit 102 in consideration of the enlarged shooting It has a relatively small and fine pattern. The macro test unit 106 is for testing a camera's performance under macro shooting conditions to obtain a detailed image by photographing a relatively small subject as close as possible. Have

2A to 2C are views illustrating a wide-angle test unit, a telephoto test unit, and a macro test unit constituting the camera test unit.

The wide-angle test unit 102 shown in FIG. 2A is provided with a pattern alignment mark 202a, a gray level bar 204, a color bar 206, and a line pair chart 208a. The pattern alignment mark 202a is for inspecting the distortion aberration of the camera and compensating for the position of the wide-angle test unit 102. In the case of a camera using a low-cost lens with a large distortion aberration, accurate image correction is required before the pattern inspection to compensate for this distortion. For this, a mark for pattern alignment in the form of a 5x5 mm square dot grid is required. I use it. In the pattern alignment marks 202a provided in the wide-angle test unit 102, twenty-five marks in each of five horizontally and vertically are arranged at equal intervals over the entire area of the wide-angle test unit 102. FIG. The gray level bar 204 is used for checking brightness and is provided in the form of a bar having 16 levels of gray levels, and is for evaluating the resolution of the gray level of the camera, that is, the ability to express brightness. One gray level bar 204 is provided at each of the upper and lower centers of the wide-angle test unit 102. The color bar 206 is used for color inspection. The color bar 206 is used for color inspection using six color bars including red, green, blue, yellow, cyan, and magenta. Then, the color reproducibility is evaluated by comparing with the value of the color coordinate system. The line pair chart 208a is for focus inspection or resolution inspection, for inspecting the focus using evenly arranged horizontal or vertical line bars. To this end, line bars having various sizes, line widths, and the like are disposed at the upper left, upper right, lower left, lower right, and center of the wide-angle test unit 102, respectively, so that both the center and peripheral portions of the screen can be inspected for resolution.

The telescopic test unit 104 shown in FIG. 2B is provided with a pattern alignment mark 202b and a line pair chart 208b, each of which is the same as mentioned above in the description of FIG. 2A. However, the pattern alignment mark 202b provided in the telescopic test unit 104 is enlarged and photographed under the telephoto photographing condition, and thus the size of the pattern alignment mark provided in the wide-angle test unit 102 is taken into consideration. It is assumed to be in the form of a square dot grid of 3x3 mm which is relatively smaller than 202a). The line pair chart 208b provided in the telescopic test unit 104 is also provided with line bars having various sizes, line widths, and the like, respectively positioned on the upper left, upper right, lower left, lower right, and center of the telescopic test unit 104. Both central and peripheral resolution checks are possible.

The macro test unit 106 shown in FIG. 2C is also provided with a pattern alignment mark 202b and line pair charts 208a and 208b, each of which is the same as mentioned above in the description of FIG. 2B. However, the pattern alignment mark 202b provided in the macro test unit 106 is used as it is provided in the telephoto test unit 104, and the line pair charts 208a and 208b use the wide-angle test unit 102. ), The line pair chart 208a provided in the center and the line pair chart 208b provided in the center of the telescopic test unit 104 are used as they are.

The line pair charts 208a and 208b provided in the camera test unit 100 according to an exemplary embodiment of the present invention consist of a plurality of lines having different intervals and widths. It should be in micrometer (μm) units, but ensure sufficient separation between the line of the minimum line width and the line of the next higher line width so that the distinction is made clearly. In addition, by using the line pair charts 208a and 208b having a line width in micrometers (μm), cameras of various pixels up to 20 million pixels can be tested.

3 is a diagram illustrating an automatic resolution test using the camera test unit shown in FIG. 1. Resolution is a measure of how detailed the image can be. In other words, the higher the resolution, the more closely spaced the details can be expressed. As shown in FIG. 3, in the exemplary embodiment of the present invention, a standard deviation of a histogram of a focal point is expressed as a numerical value so that the resolution can be automatically checked by using the level of the resolution. For example, as shown in (I) of FIG. 3, the line pair charts 208a and 208b become clearer, and the histogram has a maximum standard deviation and peaks on both sides. On the contrary, if the line pair charts 208a and 208b are not clearly seen as shown in FIG. 3 (II), the standard deviation of the histogram becomes small. Therefore, by checking the histogram standard deviation on the monitor, it is possible to easily and accurately determine the resolution capability of the camera.

4 is a diagram illustrating an automatic color reproducibility test using the camera test unit shown in FIG. 1. As shown in FIG. 4, color reproducibility of the camera is evaluated by converting to an HSV color model using RGB (Red, Green, Blue) values. The HSV color model separates color information (Hue, Saturation) and brightness information (Value), among which color information (Hue) is expressed as a value between 0 ° and 360 °, and another color information (Saturation) is Expressed as 0 ~ 1 or 0% ~ 100%. Brightness information (Value) is brighter at the top and darker at the bottom.

FIG. 5 is a diagram illustrating an automatic white balance inspection using the camera test unit shown in FIG. 1. As shown in FIG. 5, when the white balance is inspected using the gray level bar 204 of the wide-angle test unit 102, a graph as shown in FIG. 5 may be obtained. The graph of FIG. 5 shows the vertical projection of the RGB values of the gray level bar 204. In the normal case, the RGB values tend to be similar regardless of the gray level change as shown in (I). In this case, as shown in (II), the RGB value shows a significant difference according to the change of gray level.

FIG. 6 is a diagram illustrating automatic distortion inspection and correction using the camera test unit illustrated in FIG. 1. Components shown by reference numeral 602 in Fig. 6 represent the pattern alignment marks 202a and 202b shown in Figs. 2A-2C. In FIG. 6I, it can be seen that the right portion of the image photographing the camera test unit 100 is distorted. To determine the degree of distortion, first, H1-H2 = Δh1 and H2-H3 = Δh2 are obtained. When Δh1 and Δh2 representing distortion levels are obtained, the screen is corrected based on these two values so that a normal screen such as (II) is formed. Determination of the distortion degree using the H value and the Δh value can be expressed by the following equation.

In addition, a pixel defect test is additionally performed. A pixel defect is classified into a white defect and a black defect. White defect inspection is to check for the presence of dead pixels. It is to cover the front of the camera's lens and take a picture to check whether there is a red, blue, or green spot in the image. . That is, at least one of the RGB pixels constituting one pixel checks whether there is a pixel that does not operate normally.

The black defect is a test for the presence of dark parts in an image of a bright white subject. The reason that a dark part exists when photographing a white subject is due to a foreign object or damage in a camera module. This black defect is inspected by photographing the white part of the camera test unit 100 shown in FIG.

7 is a diagram illustrating a configuration of a camera test system using a camera test unit according to an exemplary embodiment of the present invention. As shown in FIG. 7, the inspector 704 mounts the camera 702 to the holder and performs shooting control so that the camera test unit 100 as shown in FIG. 1 can be photographed. The camera 702 includes a camera module (internal / external) mounted on a mobile communication terminal as well as a digital still camera and a digital video camera. An image of the camera test unit 100 captured by the camera 702 is transmitted to a computer system 706 in which a camera test program is installed and operated. The computer system 706 automatically analyzes the image transmitted from the camera 702 through a camera test program and displays the inspection result on the monitor. The inspector 704 checks the inspection result displayed on the monitor of the computer system 706 to determine whether the camera 702 is ok.

8 is a flowchart illustrating a camera inspection method for testing the performance of a camera using the camera test unit shown in FIG. 1. As shown in FIG. 8, the inspector 704 mounts the camera 702 to the holder so that the camera test unit 100 as shown in FIG. 1 can be photographed (802). The inspector 704 performs wide-angle, telephoto, and macro photography through the camera 702 mounted on the cradle, and each photographed image is transmitted to the computer system 706 where the camera test program is installed and operated (804). ).

Each image sent to the computer system 706 is automatically analyzed through a camera test program and the inspection result is displayed on the monitor. The inspection performed at this time includes the automatic resolution check (806 (see FIG. 3)), the automatic color reproducibility check (808 (see FIG. 4)), the automatic white balance check (810, see FIG. 5), the automatic distortion check and correction (812, 6). Thereafter, the pixel defect inspection image is additionally photographed and transmitted to the computer system 706 (814). Pixel defects such as white defect inspection and black defect inspection are inspected through the pixel defect inspection image (816). However, the imaging of the pixel defect inspection may be performed together with the aforementioned wide-angle-tele-macro imaging. The inspector 704 checks the inspection result displayed on the monitor of the computer system 706 to determine whether the camera 702 is ok (818).

The camera test unit and the camera inspection method using the same according to the present invention allow the test operation to be performed more quickly by testing the camera using a single camera test unit.

In addition, by automatically analyzing the image of the above-described test unit through a test program on a computer system to enable a quick, objective and accurate camera test.

Claims (9)

A plurality of focal length test units integrally provided to collectively test a plurality of different focal length photographing performances; And a line pair chart having different line spacings and line widths provided for each of the test units for each focal length to inspect the focus and the resolution for each pixel number from the low pixel to the high pixel. The test unit of claim 1, wherein the test units for focal lengths include: Camera test unit including wide-angle test unit, telephoto test unit, macro test unit. According to claim 2, wherein the wide-angle test unit, Color bars for color inspection; The camera test unit further includes a brightness level gray level bar. The method of claim 2, A mark for pattern alignment for inspecting distortion aberration of a camera and position compensation of a camera test unit is provided for each of the wide-angle test unit, the telephoto test unit, and the macro test unit; A camera test unit having a larger size of a pattern alignment mark provided in the wide-angle test unit than a pattern alignment mark provided in the telephoto test unit and the macro test unit. The method of claim 2, And the macro test unit shares a part of a line pair chart and a pattern alignment mark of the wide-angle test unit and the telephoto test unit. The method of claim 1, The camera test unit, wherein the narrowest line width of the line pair chart is in micrometer (μm). Photographing a single camera test unit to obtain an image; Transmit the image to a computer system 706 in which a camera test program is installed and operated; An image transmitted to the computer system 706 is automatically analyzed through the camera test program and the inspection result is displayed on a monitor; Camera inspection unit using a camera test unit to determine whether or not the camera (702) by checking the inspection results displayed on the monitor of the computer system (706). The method of claim 7, wherein the camera test unit; A plurality of focal length test units integrally provided to collectively test a plurality of different focal length photographing performances; Using a camera test unit including a line pair chart having different line intervals and line widths provided for each of the test units for each focal length to check the focus and the resolution by the number of pixels from the low pixel to the high pixel. Camera inspection method. 8. The computer system of claim 7, wherein the tests performed automatically on the computer system comprise; Camera inspection method using camera test unit including automatic resolution check, automatic color reproducibility check, automatic white balance check, automatic distortion check and correction, and pixel defect check.

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