CN117524024A - Halation measurement method and system for display device - Google Patents
Halation measurement method and system for display device Download PDFInfo
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Abstract
The application discloses a halation measurement method and a halation measurement system for a display device. The halation measurement method for a display device includes: respectively acquiring a first image of a tested display shot under a first exposure time period and a second image of the tested display shot under a second exposure time period, acquiring a bright area brightness value from the first image, acquiring a dark area brightness value and a halation area brightness value from the second image, and jointly determining the halation value of the halation area based on the bright area brightness value, the dark area brightness value and the halation area brightness value. According to the method, the brightness information of the bright area and the halo area can be respectively obtained through multiple groups of exposure, so that the halo value is calculated based on the image data of the bright area obtained under the condition that the bright area is brightest in imaging and the image data of the halo area and the dark area obtained under the condition that the halo area is brightest in imaging, the condition that the brightness information of the halo area is lost is avoided, and the problem that the halo calculation result is large in error is solved.
Description
Technical Field
The application relates to the technical field of display, in particular to a halo measurement method and a halo measurement system for a display device.
Background
Display devices employing Mini LED (sub-millimeter light emitting diode) backlighting techniques, such as: when a display panel of the Mini LED backlight television displays a bright color object, backlight corresponding to the bright color object is also lightened, and because the lightened backlight area is not completely matched with pixels corresponding to the bright color object, a 'halo' appears at the outline edge of the bright color object displayed on the display panel, namely, a halation phenomenon affecting the appearance is generated. Halation is one of typical image problems of a display device, and thus accurate evaluation of halation of the display device is required.
Aiming at the halo region with smaller self brightness, the related technology can cause the problem of loss of brightness information of a low-brightness region because the gray scale occupation of the acquired halo region is smaller, so that the error of the halo calculation result is large, and the halo region cannot be accurately evaluated.
Disclosure of Invention
The embodiment of the application provides a halo measuring method and a halo measuring system for a display device, which are used for solving the technical problem of large halo calculation result error caused by loss of brightness information of a low-brightness area in the related technology.
In order to solve the technical problems, the embodiment of the application discloses the following technical scheme:
in a first aspect, there is provided a halo measurement method for a display device, comprising:
acquiring a first image of a display to be tested, which is shot under a first exposure time, wherein the first image comprises a preset test pattern, and the first exposure time is the exposure time corresponding to a camera when the brightness value of the test pattern reaches a first threshold value;
acquiring a brightness value of a bright area on the first image, wherein the brightness value of the bright area is the brightness value of the test pattern;
acquiring a second image of the tested display, which is shot in a second exposure time period, wherein the second image comprises the test pattern, and the second exposure time period is the exposure time period corresponding to the camera when the brightness value of a halo area around the test pattern reaches a second threshold value;
acquiring a dark area brightness value and a halation area brightness value on the second image, wherein the dark area brightness value is the brightness value of the rest areas except the area corresponding to the test pattern and the halation area on the second image;
and determining a halo value of the halo region based on the bright region luminance value, the dark region luminance value, and the halo region luminance value.
With reference to the first aspect, the determining the halo value of the halo region based on the bright region luminance value, the dark region luminance value, and the halo region luminance value includes:
determining a halo value for the halo region by the formula:
wherein halo is the halo value, L, of the halo region Bright area For the brightness value of the bright area, L Dark area For the dark area brightness value, L Halo region And (5) obtaining the brightness value of the halation area.
With reference to the first aspect, the halo region luminance value on the second image is obtained by:
removing salt and pepper noise in the second image to obtain a third image;
normalizing the third image based on the second exposure time length to obtain a fourth image;
acquiring a central point of a halation area from the third image;
acquiring a first integral value of a first area from the fourth image, wherein the first integral value is the sum of gray values of all pixel points in the first area, the first area is a circular area taking the central point of the halation area as the center and taking a detection radius as the radius, and the detection radius is a pixel distance obtained by converting the detection diameter of a brightness meter based on the size and resolution of the display to be detected;
determining a quotient of the first integrated value and an area of the first region as a luminance value of the first region;
and determining the brightness value of the first area as the brightness value of the halation area on the second image.
With reference to the first aspect, acquiring a center point of a halo region from the third image includes:
performing binarization processing on the third image to obtain a fifth image; the fifth image comprises a first bright image with a brightness value of 1, the first bright image comprising a first contour parallel to a first direction;
acquiring edge points of a halation area from the first contour; the halo region edge points extend from the center point of the test pattern along the direction perpendicular to the first direction and then intersect with the first contour, and the center point of the test pattern is acquired based on the first image;
and translating the distance corresponding to the detection radius from the edge point of the halation area along the direction perpendicular to the first contour and towards the direction away from the first bright image to obtain the center point of the halation area.
With reference to the first aspect, the dark area luminance value on the second image is obtained by:
acquiring a central point of a dark area from the third image based on the central point of the display to be measured and a coordinate transformation relation between a preset central point of the dark area and the central point of the display to be measured;
obtaining a second integral value of a second area from the fourth image, wherein the second integral value is the sum of gray values of all pixel points in the second area, and the second area is a circular area taking the central point of the dark area as the center and the detection radius as the radius;
determining a quotient of the second integrated value and an area of the second region as a luminance value of the second region;
and determining the brightness value of the second area as the dark area brightness value on the second image.
With reference to the first aspect, obtaining a brightness value of a bright area on the first image includes:
removing salt and pepper noise in the first image to obtain a sixth image;
normalizing the sixth image based on the first exposure time length to obtain a seventh image;
acquiring a center point of the test pattern from the sixth image;
obtaining a third integral value of a third area from the seventh image, wherein the third integral value is the sum of gray values of all pixel points in the third area, and the third area is a circular area taking the center point of the test pattern as the center and the detection radius as the radius;
determining a quotient of the third integrated value and an area of the third region as a luminance value of the third region;
and determining the brightness value of the third area as the brightness value of the bright area on the first image.
With reference to the first aspect, acquiring a center point of the test pattern from the sixth image includes:
binarizing the sixth image to obtain an eighth image; the eighth image comprises a second bright image with a brightness value of 1;
acquiring a center point of the second bright image;
and determining the center point of the second bright image as the center point of the test pattern.
With reference to the first aspect, the detection radius is determined by the following formula:
wherein R is the detection radius, D is the detection diameter of the luminance meter, pixelWidth is the resolution of the display to be detected in the length direction, A is the size of the display to be detected, and m and n are the aspect ratios of the display to be detected.
In a second aspect, there is provided a halo measurement system for a display device, comprising:
the display to be tested is used for displaying a preset test pattern;
the camera is used for generating a shooting image of the display to be tested under the first exposure time length and the second exposure time length respectively; the photographed image includes the test pattern;
and the server is respectively connected with the tested display and the camera and is used for acquiring the halation value of the halation area around the tested graph by adopting the halation measuring method for the display device according to the first aspect and the embodiments so as to evaluate the halation of the tested display through the halation value.
With reference to the second aspect, the ratio of the area of the test pattern to the area of the display to be tested is less than or equal to 10%.
One of the above technical solutions has the following advantages or beneficial effects:
compared with the prior art, the halation measurement method for the display device comprises the following steps: respectively acquiring a first image of a tested display shot under a first exposure time period and a second image of the tested display shot under a second exposure time period, acquiring a bright area brightness value from the first image, acquiring a dark area brightness value and a halation area brightness value from the second image, and jointly determining the halation value of the halation area based on the bright area brightness value, the dark area brightness value and the halation area brightness value. According to the halo measuring method for the display device, the brightness information of the bright area and the brightness information of the halo area can be respectively obtained through multiple groups of exposure, so that the halo value is calculated based on the image data of the bright area obtained under the condition that the bright area is brightest to image and the image data of the halo area and the dark area obtained under the condition that the halo area is brightest to image, the condition that the brightness information of the halo area is lost is avoided to the greatest extent, and the problem that the error of the halo calculating result is large is solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a display device employing Mini LED backlight technology;
FIG. 2 is a schematic view of halo effect of a display panel;
FIG. 3 is a schematic diagram of a halo measurement system for a display device according to an embodiment of the present application;
FIG. 4 is a schematic diagram illustrating a positional relationship between the display and the field of view of the camera in FIG. 3;
fig. 5 is an overall flow chart of a halo measurement method for a display device according to an embodiment of the present application;
FIG. 6 is a seventh image schematic of an embodiment of the present application;
FIG. 7 is a schematic diagram of a brightness distribution curve of a pixel point in a seventh image;
FIG. 8 is a fourth image schematic of an embodiment of the present application;
FIG. 9 is a schematic diagram of a brightness distribution curve of a pixel point in a fourth image;
fig. 10 is a specific flowchart of a halo measurement method for a display device according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. In the description of the present application, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," etc. indicate or are based on the orientation or positional relationship shown in the drawings, merely for convenience of description and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Referring to fig. 1 and fig. 2 together, fig. 1 illustrates a block diagram of a display device employing Mini LED backlight technology, and fig. 2 illustrates a halo effect of a display panel. For display devices employing Mini LED backlight technology, for example: when the display panel 101 displays the bright color object a, the Mini LED backlight area 102 corresponding to the bright color object a will also be lighted, and since the backlight emitted by the Mini LED backlight area 102 will pass through the diffusion plate 103 before reaching the display panel 101, an optical diffusion effect is generated, which will cause that the diffused backlight area is not completely matched with the pixels corresponding to the bright color object, so that when the display panel 101 displays the bright color object a, a "halo" will appear on the contour edge of the bright color object a, that is, a halation effect affecting the look and feel is generated. In the present embodiment, the area of brightness variation generated around the outline of the bright color object a is referred to as a halo region B.
The applicant has noted that it is possible in the related art to take a shot of the display panel 101 in the single exposure mode with a camera and then process the shot image, thereby acquiring the brightness information of the halo region B and evaluating the quality of the halo. However, for the halo region B with smaller brightness, under the condition that the camera cannot overexposure, the obtained gray scale of the halo region B is less due to the limitation of the dynamic range of the camera, namely, only a small gray scale represents the halo at the moment, so that the problem of loss of brightness information in a low-brightness region is caused, and the calculation error of the halo value is caused to be larger.
In view of this, the embodiment of the present application provides a halo measurement system for a display device, which obtains accurate brightness data of a bright area and brightness data of a halo area according to two groups of captured image data under different exposure times, and calculates a halo value, so as to evaluate the quality of the halo, and improve the problem of large error of the halo calculation result under single exposure, so as to solve at least part of the above technical problems.
Referring to fig. 3, fig. 3 illustrates a block diagram of a halo measurement system for a display device according to an embodiment of the present application. The halation measurement system for a display device comprises a display 1 to be measured, a camera 2 and a server 3. The display 1 to be tested is used for displaying a preset test pattern. The camera 2 is used for generating a photographed image of the tested display under the first exposure time period and the second exposure time period respectively, wherein the photographed image comprises a test pattern. The server 3 is connected to the tested display 1 and the camera 2 respectively, and is configured to obtain a halo value of a halo region around the test pattern by using the halo measurement method for a display device according to the embodiment of the present application, so as to evaluate the halo of the tested display 1 by using the halo value. The server 3 is further configured to send a test pattern to the display 1 to be tested, and configure the first exposure time period and the second exposure time period as parameters to the camera 2.
In some embodiments, the ratio of the area of the test pattern to the area of the display 1 under test may be less than or equal to 10%. Thus, since the luminance of the display 1 to be measured is adjusted based on the pixel average luminance APL (Average Pixel Level) value, the display 1 to be measured can reach the maximum luminance level when the APL value of the display 1 to be measured is less than 10%. Since the halation effect is more easily perceived in a dark scene, measuring the halation width in the brightest condition of the display 1 under test can ensure that the measurement is performed in the worst condition of the halation effect, and thus a more accurate evaluation result can be obtained.
Referring to fig. 4, fig. 4 is a schematic diagram illustrating a positional relationship between the display to be tested and a field of view photographed by the camera in fig. 3. In some embodiments, alignment calibration of the positions of the display 1 under test and the camera 2 is required before halo measurements are made, i.e. the size and position of the display 1 under test imaged within the field of view of the camera 2 need to be fixed. Specifically, the camera 2 is adjusted to shoot along the direction perpendicular to the display 1 to be tested, the display 1 to be tested may be located at the center of the camera shooting field of view C, and each pixel of the display 1 to be tested corresponds to each pixel imaged by the camera 2, for example, assuming that the resolution of the display 1 to be tested is 1920×1080, then the size of the picture area occupied by the imaging of the display 1 to be tested in the image shot by the camera 2 should also be 1920×1080, at this time, the resolution of the image shot by the camera 2 may be greater than or equal to the resolution of the display 1 to be tested, then the center point O of the display 1 to be tested 1 Is (X) Display device ，Y Display device ) MeasuringHalo region center point O of test pattern S 2 Is located outside the outline of the test pattern S, the dark area center point O based on the proportional relationship of each pixel of the display 1 under test to each pixel imaged by the camera 2 3 Coordinates of (2) and the center point O of the display 1 under test 1 The coordinates of which have a preset coordinate transformation relationship. Thus, the method is more beneficial to the subsequent positioning calculation of the position of the pixel point.
With continued reference to fig. 4, in the embodiment of the present application, the test pattern S is preset by the server 3 and is sent to the tested display 1 for displaying. In some embodiments, the test pattern S may be a solid rectangle. One side of the rectangle may be parallel to a first direction (e.g., X direction), the other side may be parallel to a second direction (e.g., Y direction), the first direction may be an extending direction of a long side of the display 1 to be tested, and the first direction may be an extending direction of a wide side of the display 1 to be tested. Illustratively, one side of the rectangle has a length 0.33pixel Width,pixel Width which is the resolution of the long side of the display 1 under test, and the other side of the rectangle has a length 0.33pixel Height,pixel Height which is the resolution of the wide side of the display 1 under test. Like this, set up the test pattern S of rectangle, can fully embody the halation district of horizontal and perpendicular two directions, the convenience is measured, and can simulate the less bright color object area of size well to fully satisfy the test demand.
In other embodiments, the test pattern may also be a parallelogram, a rectangle with an included angle with the side of the display 1 to be tested, a trapezoid, etc., as long as the test requirement can be met, which is not particularly limited in the embodiments of the present application.
In some embodiments, the camera 2 needs to make exposure parameter settings before taking a picture of the display 1 under test. Specifically, according to the model of the camera 2 and the brightness of the display 1 to be tested, the first exposure time period should be preset so as to make the imaging brightness of the bright area corresponding to the test pattern reach the brightest under the condition that the bright area corresponding to the test pattern is not overexposed, and the second exposure time period should be preset so as to make the imaging brightness of the halation area reach the brightest under the condition that the halation area is overexposed. Due to the bright halo regionThe degree is typically less than the brightness of the test pattern area, so the second exposure period is typically greater than the first exposure period. In some examples, the second exposure time period T 2 A first exposure time period T equal to 10 times 1 T, i.e 2 ＝10×T 1 。
In some examples, the exposure time period corresponding to the camera when the brightness value of the test pattern reaches the first threshold may be determined as the first exposure time period, and the exposure time period corresponding to the camera when the brightness value of the halo region around the test pattern reaches the second threshold may be determined as the second exposure time period. Specifically, the first threshold and the second threshold may be set according to the luminance value of the test pattern and the luminance value of the halo region at the time of overexposure, respectively. That is, the first threshold value is the maximum brightness value that can be reached by the test pattern when the test pattern displayed by the tested display 1 is not overexposed. The second threshold value refers to the maximum brightness value that can be reached by the halo region in the case that the halo region around the test pattern displayed by the display 1 to be tested is not overexposed. It is understood that if the brightness value of the test pattern exceeds the first threshold value, the test pattern is in an overexposed state. If the brightness value of the halo area around the test pattern exceeds the second threshold value, the halo area around the test pattern is in an overexposed state.
By setting the plurality of groups of exposure, the maximum brightness information exists in the bright area corresponding to the test pattern under the first exposure time, and the maximum brightness information exists in the halation area under the second exposure time, so that the loss of the brightness information of the low-brightness area of the halation area can be greatly reduced.
The halation measurement method for the display device employed by the server 3 of the embodiment of the present application is described below.
Referring to fig. 5, fig. 5 illustrates an overall flow of a halo measurement method for a display device according to an embodiment of the present application. The halation measurement method for the display device comprises the following steps:
step 501: and acquiring a first image of the tested display shot under the first exposure time.
The first image comprises a preset test pattern.
In this step, the preset test pattern is a test pattern preset by the server 3 and sent to the display 1 to be tested for display for measuring halation. Wherein the shape, size and position of the test pattern can be preset with reference to the related description in the foregoing embodiments. "
The first image captured is an image obtained after the camera 2 captures the display 1 under test. Before shooting, the camera 2 may perform parameter setting and alignment calibration of the position according to the related descriptions in the foregoing embodiments, so as to ensure that the size and the position of the image formed by the display 1 to be tested in the field of view of the camera 2 may be relatively fixed.
Specifically, the server 3 may send a mapping signal to the camera 2, and the camera 2 may acquire a first image of the display under test at a first exposure time period in response to the mapping signal.
In some embodiments, the first image has an accuracy in the range of 8 bits to 12 bits. In some examples, the precision of the first image is a range value of any one or both of 8 bits, 10 bits, and 12 bits. Thus, the image precision is higher, and the more accurate brightness information image is obtained.
Step 502: and acquiring a brightness value of a bright area on the first image.
The brightness value of the bright area is the brightness value of the test pattern.
In some embodiments, the bright area luminance value on the first image may be obtained by:
and step one, removing salt and pepper noise in the first image to obtain a sixth image.
Specifically, salt and pepper noise, also known as impulse noise, is a noise frequently seen in images, which is a randomly occurring white or black dot, possibly with black pixels in bright areas or white pixels in dark areas (or both).
In some embodiments, the salt and pepper noise in the first image may be filtered out by means of median filtering. The size of the filter kernel may be 3×3, for example. In other embodiments, the salt and pepper noise in the first image may also be filtered by using a mean filtering or statistical method, which is not specifically limited in the embodiments of the present application. In this way, salt and pepper noise generated by the camera in the imaging process can be eliminated.
And secondly, carrying out normalization processing on the sixth image based on the first exposure time length to obtain a seventh image.
Referring to fig. 6, fig. 6 illustrates a seventh image according to an embodiment of the present application. Specifically, dividing the gray value of each pixel point on the sixth image by the first exposure time length to obtain a seventh image P 7 Gray values of the respective pixels. In this way, the influence of cameras with different exposure time lengths and different types of differences on the image processing result can be eliminated, and the original brightness of the sixth image can be obtained.
Referring to fig. 7, fig. 7 illustrates a brightness distribution curve of a pixel point in a seventh image. With a seventh image P 7 For example, the precision of the mask is 12 bits, the gray level (Graylevel) level of the halo region is n, and the gray level duty ratio is n/4095 in the first exposure time.
And thirdly, acquiring the center point of the test pattern from the sixth image.
In some examples, step three may be performed by:
and a first step of binarizing the sixth image to obtain an eighth image.
Wherein the eighth image comprises a second bright image with a brightness value of 1. The eighth image is displayed in full darkness except for the second bright image.
Specifically, a global threshold for the sixth image may be acquired. And then, processing the brightness value of each pixel point in the sixth image based on the global threshold value to generate a binarized eighth image.
In some examples, a maximum inter-class variance method (Otsu algorithm) may be employed to generate the eighth image. Specifically, when the Otsu algorithm is adopted to perform global automatic threshold segmentation on the sixth image, each pixel with a brightness value greater than the global threshold in the sixth image can be classified into the foreground, the brightness value is all assigned to 1, each pixel with a brightness value less than the global threshold in the sixth image is classified into the background, and the brightness value is all assigned to 0, so that an eighth image can be obtained, wherein each pixel with a brightness value of 1 forms a second bright image.
And secondly, acquiring the center point of the second bright image.
Third, the center point of the second bright image is determined as the center point O of the test pattern 4 。
Specifically, the center point O of the test pattern 4 Center point O with display 1 under test 1 May coincide.
Step four, from the seventh image P 7 In the process, a third region D is obtained 3 Is included in the first integrated value of (a).
Wherein the third integrated value is a third region D 3 The sum of gray values of the pixels in the third region D 3 Is based on the center point O of the test pattern 4 Is a circular area with the detection radius R as the radius. The detection radius R is a pixel distance obtained by converting the detection diameter of the luminance meter based on the size and resolution of the display 1 to be measured.
Specifically, the luminance meter is an instrument for measuring the luminance and chrominance in a handheld manner, and in this embodiment of the present application, the luminance and chrominance may be used to detect the luminance and chrominance of the corresponding area of the first image.
In some examples, the detection radius R may be determined by the following formula:
where R is a detection radius, D is a detection diameter (in millimeters mm) of the luminance meter, pixel Width is a resolution of the display 1 to be tested in a length direction, the resolution of the display 1 to be tested may be expressed as pixel width×pixel Height, a is a size (in inches) of the display 1 to be tested, m and n are aspect ratios of the display 1 to be tested, that is, the aspect ratio of the display 1 to be tested is expressed as m: n.
Step five, determining the quotient of the third integral value and the area of the third area as a third area D 3 Is a luminance value of (a).
That is, the third region D 3 Luminance value=third integrated value/third region D 3 Is a part of the area of the substrate. Third region D 3 Area=pi×r 2 R is the detection radius.
Step six, the third area D 3 Is determined as the luminance value of the bright area on the first image.
By the method, the brightness value of the bright area on the first image can be obtained, so that more accurate brightness of the bright area can be obtained, and the bright area and the halation area can be distinguished more accurately.
Step 503: and acquiring a second image of the tested display shot under the second exposure time.
Wherein the second image comprises a test pattern. The brightness value of the bright area corresponding to the test pattern is larger than the brightness value of the halation area under the influence of the second exposure time, so that the bright area corresponding to the test pattern is in an overexposure state in the second image, and the halation area reaches the maximum bright area.
Specifically, the server 3 may send a mapping signal to the camera 2, and the camera 2 may acquire a second image of the display under test at a second exposure time period in response to the mapping signal.
In some embodiments, the second image has an accuracy in the range of 8 bits to 12 bits. In some examples, the precision of the second image is a range value of any one or both of 8 bits, 10 bits, and 12 bits. Thus, the image precision is higher, and the more accurate brightness information image is obtained.
Step 504: and acquiring a dark area brightness value and a halation area brightness value on the second image.
The brightness value of the dark area is the brightness value of the rest areas except the area corresponding to the test pattern and the halation area on the second image.
In some embodiments, halo region luminance values on the second image may be obtained by:
and step one, removing salt and pepper noise in the second image to obtain a third image.
It should be noted that, the embodiment of the first step may refer to the embodiment of the first step in the step 502, which is not separately described herein.
And step two, carrying out normalization processing on the third image based on the second exposure time length to obtain a fourth image.
Referring to fig. 8, fig. 8 illustrates a fourth image according to an embodiment of the present application. Specifically, dividing the gray value of each pixel point on the third image by the second exposure time length to obtain a fourth image P 4 Gray values of the respective pixels. In this way, the influence of cameras with different exposure time lengths and different types of differences on the image processing result can be eliminated, and the original brightness of the third image can be obtained.
Referring to fig. 9, fig. 9 illustrates a brightness distribution curve of a pixel point in the fourth image. In a fourth image P 4 For example, 12 bits, in the case where the second exposure period=10×the first exposure period, the gray scale (graylevel) level of the halo region is 10n, and the gray scale duty ratio is 10n/4095.
And thirdly, acquiring the center point of the halation area from the third image.
In some examples, step three may be performed by:
and a first step of binarizing the third image to obtain a fifth image.
Wherein the fifth image comprises a first bright image with a brightness value of 1, the first bright image comprising a first contour parallel to the first direction.
It should be noted that, the embodiment of the first step of the third step 502 may be referred to the embodiment of the first step of the third step, and will not be separately described herein.
And secondly, acquiring edge points of the halation area from the first contour.
Wherein the halo region edge point is an intersection with the first contour after extending from the center point of the test pattern in a direction perpendicular to the first direction (e.g., in the Y direction). Center point O of test pattern 4 The specific embodiments of the first to third steps in the step 502 are based on the first image acquisition, and will not be described herein separately.
That is, taking the example that the test pattern is rectangular, there are two first contours parallel to the first direction in the first bright image, and after extending from the center point of the test pattern along the direction perpendicular to the first direction, the intersection point with any one of the first contours can be determined as the edge point of the halation area. The first direction may be parallel to the long side extending direction of the rectangle, or may be parallel to the wide side extending direction of the rectangle.
Third, translating the detection radius from the edge point of the halation area along the direction perpendicular to the first contour to a direction far away from the first bright image to obtain the center point O of the halation area 2 。
By the method, the center point of the halo region can be extracted more accurately according to more halo brightness information, so that the calculation accuracy of the halo value is improved.
Step four, from the fourth image P 4 In the process, a first region D is acquired 1 Is a first integral value of (a).
Wherein the first integrated value is a first region D 1 The sum of gray values of the pixels in the first region D 1 Is based on the central point O of the halation region 2 Is a circular area with the detection radius R as the radius. The calculation of the detection radius R can be referred to in the step 502 and the related content of the step four is not separately described herein.
Step five, the first integral value and the first area D 1 Is determined as the quotient of the areas of the first region D 1 Is a luminance value of (a).
That is, the first region D 1 Luminance value=first integrated value/first region D 1 Is a part of the area of the substrate. First region D 1 Area=pi×r 2 R is the detection radius.
Step six, the first area D 1 Is determined as the halo region luminance value on the second image.
By the method, the brightness information of the halation area can be extracted more, so that the lost data of the brightness of the low-brightness area is reduced, and the accuracy of halation calculation is improved.
In some embodiments, dark region luminance values on the second image may be obtained by:
and step seven, acquiring the central point of the dark area from the third image based on the central point of the display to be measured and the coordinate transformation relation between the preset central point of the dark area and the central point of the display to be measured.
With continued reference to FIG. 8, in particular, the center point O of the display under test 1 Is (X) Display device ，Y Display device ) Based on experiments and related data analysis, in case each pixel of the display 1 under test corresponds to each pixel imaged by the camera 2, the dark area center point O 3 Center point O of display to be tested 1 The coordinate transformation relation of (a) is as follows: dark area center point O 3 Coordinates (X) Dark and dark ，Y Dark and dark )＝(X Display device +pixel Width×0.4，Y Display device + pixel Height x 0.4). The pixel Width and pixel Height are the pixel sizes of the measured display 1 in the length direction and the Width direction of the resolution.
It should be noted that, in the seventh step and the step 504, the foregoing step three may be performed simultaneously.
Step eight, acquiring a second area D from the fourth image 2 Is included in the second integrated value of (a).
Wherein the second integrated value is a second region D 2 The sum of gray values of the pixels in the second region D 2 Is based on the central point O of the dark area 3 Is a circular area with the detection radius R as the radius. The calculation of the detection radius R can be referred to in the step 502 and the related content of the step four is not separately described herein.
Step nine, the second integrated value is combined with the second area D 2 Is determined as the quotient of the areas of the second areas D 2 Is a luminance value of (a).
That is, the second region D 2 Luminance value=second integrated value/second region D 2 Is a part of the area of the substrate. Second region D 2 Area=pi×r 2 R is the detection radius.
Step ten, the second area D 2 Is determined as the dark area luminance value on the second image.
By the method, the brightness value of the halation area and the brightness value of the dark area on the second image are obtained, the brightness information of the low-brightness area can be fully obtained through longer exposure time, the condition that the brightness information of the low-brightness area is lost is avoided, and therefore more accurate brightness of the dark area and brightness of the halation area are obtained, and accurate calculation of the halation area is facilitated.
Step 505: the halo value of the halo region is determined based on the bright region luminance value, the dark region luminance value, and the halo region luminance value.
Wherein the halation value is used for evaluating halation quality of the display 1 under test.
In some embodiments, the halo value of the halo region may be determined by the following equation:
wherein halo is the halo value of the halo region, L Bright area For brightness value of bright area, L Dark area Is the brightness value of the dark area L Halo region Is the halo region luminance value.
In order to more clearly describe the halo measurement method for a display device according to the embodiment of the present application, referring to fig. 10, fig. 10 illustrates a specific flowchart of the halo measurement method for a display device according to the embodiment of the present application. The halo measurement method for the display device according to the embodiment of the application may include the following steps:
and (5) aligning and setting parameters of the camera.
The tested display displays the test pattern.
Under the triggering of the image capturing signal, a first image of the tested display under the first exposure time period and a second image of the tested display under the second exposure time period are respectively obtained.
For the first image, median filtering processing, exposure time normalization processing, and bright area luminance value calculation are sequentially performed.
And for the second image, sequentially performing median filtering processing, exposure time normalization processing and halo region brightness value calculation and dark region brightness value calculation.
Wherein the size of the detection radius converted by the luminance meter diameter can be obtained before the luminance value calculation of the bright area, the luminance value calculation of the halation area, and the luminance value calculation of the dark area are performed.
It can be understood that, according to the halo measuring method for the display device of the embodiment of the present application, luminance information of a bright area and a halo area can be obtained respectively through multiple sets of exposure, so that a halo value is calculated based on image data of the bright area obtained when the bright area is brightest in imaging and image data of the halo area and a dark area obtained when the halo area is brightest in imaging, thereby avoiding the condition that the luminance information of the halo area is lost to the greatest extent, and improving the problem that the halo calculation result has a large error.
Accordingly, the halo measuring system for the display device provided by the embodiment of the application can preset a test pattern, and respectively acquire the brightness information of the bright area and the halo area through multiple groups of exposure, so that the halo value is calculated based on the image data of the bright area acquired under the condition that the bright area is brightest in imaging and the image data of the halo area and the dark area acquired under the condition that the halo area is brightest in imaging, the condition that the brightness information of the halo area is lost is avoided to the greatest extent, and the problem that the halo calculating result error is large is solved.
The foregoing describes in detail a halo measurement method and system for a display device provided in the embodiments of the present application, and specific examples are applied to illustrate the principles and embodiments of the present application, where the foregoing description of the embodiments is only for helping to understand the technical solutions and core ideas of the present application; those of ordinary skill in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. A halo measurement method for a display device, comprising:
acquiring a first image of a display to be tested, which is shot under a first exposure time, wherein the first image comprises a preset test pattern, and the first exposure time is the exposure time corresponding to a camera when the brightness value of the test pattern reaches a first threshold value;
acquiring a brightness value of a bright area on the first image, wherein the brightness value of the bright area is the brightness value of the test pattern;
acquiring a second image of the tested display, which is shot in a second exposure time period, wherein the second image comprises the test pattern, and the second exposure time period is the exposure time period corresponding to the camera when the brightness value of a halo area around the test pattern reaches a second threshold value;
acquiring a dark area brightness value and a halation area brightness value on the second image, wherein the dark area brightness value is the brightness value of the rest areas except the area corresponding to the test pattern and the halation area on the second image;
and determining a halo value of the halo region based on the bright region luminance value, the dark region luminance value, and the halo region luminance value.
2. The halo measurement method for a display device according to claim 1, wherein the determining the halo value of the halo region based on the bright region luminance value, the dark region luminance value, and the halo region luminance value comprises:
determining a halo value for the halo region by the formula:
wherein halo is the halo value, L, of the halo region Bright area For the brightness value of the bright area, L Dark area For the dark area brightness value, L Halo region And (5) obtaining the brightness value of the halation area.
3. The halation measurement method for a display device according to claim 1, wherein the halation area luminance value on the second image is obtained by:
removing salt and pepper noise in the second image to obtain a third image;
normalizing the third image based on the second exposure time length to obtain a fourth image;
acquiring a central point of a halation area from the third image;
acquiring a first integral value of a first area from the fourth image, wherein the first integral value is the sum of gray values of all pixel points in the first area, the first area is a circular area taking the central point of the halation area as the center and taking a detection radius as the radius, and the detection radius is a pixel distance obtained by converting the detection diameter of a brightness meter based on the size and resolution of the display to be detected;
determining a quotient of the first integrated value and an area of the first region as a luminance value of the first region;
and determining the brightness value of the first area as the brightness value of the halation area on the second image.
4. A halo measurement method for a display device according to claim 3, wherein obtaining a center point of a halo region from the third image comprises:
performing binarization processing on the third image to obtain a fifth image; the fifth image comprises a first bright image with a brightness value of 1, the first bright image comprising a first contour parallel to a first direction;
acquiring edge points of a halation area from the first contour; the halo region edge points extend from the center point of the test pattern along the direction perpendicular to the first direction and then intersect with the first contour, and the center point of the test pattern is acquired based on the first image;
and translating the distance corresponding to the detection radius from the edge point of the halation area along the direction perpendicular to the first contour and towards the direction away from the first bright image to obtain the center point of the halation area.
5. A halo measurement method for a display device according to claim 3, characterized in that the dark area luminance value on the second image is obtained by:
acquiring a central point of a dark area from the third image based on the central point of the display to be measured and a coordinate transformation relation between a preset central point of the dark area and the central point of the display to be measured;
obtaining a second integral value of a second area from the fourth image, wherein the second integral value is the sum of gray values of all pixel points in the second area, and the second area is a circular area taking the central point of the dark area as the center and the detection radius as the radius;
determining a quotient of the second integrated value and an area of the second region as a luminance value of the second region;
and determining the brightness value of the second area as the dark area brightness value on the second image.
6. A halo measurement method for a display device according to claim 3, wherein obtaining a bright area luminance value on the first image comprises:
removing salt and pepper noise in the first image to obtain a sixth image;
normalizing the sixth image based on the first exposure time length to obtain a seventh image;
acquiring a center point of the test pattern from the sixth image;
obtaining a third integral value of a third area from the seventh image, wherein the third integral value is the sum of gray values of all pixel points in the third area, and the third area is a circular area taking the center point of the test pattern as the center and the detection radius as the radius;
determining a quotient of the third integrated value and an area of the third region as a luminance value of the third region;
and determining the brightness value of the third area as the brightness value of the bright area on the first image.
7. The halation measurement method for a display device according to claim 6, wherein obtaining the center point of the test pattern from the sixth image comprises:
binarizing the sixth image to obtain an eighth image; the eighth image comprises a second bright image with a brightness value of 1;
acquiring a center point of the second bright image;
and determining the center point of the second bright image as the center point of the test pattern.
8. The halo measurement method for a display device according to any one of claims 3 to 7, wherein the detection radius is determined by the following formula:
wherein R is the detection radius, D is the detection diameter of the luminance meter, pixelWidth is the resolution of the display to be detected in the length direction, A is the size of the display to be detected, and m and n are the aspect ratios of the display to be detected.
9. A halo measurement system for a display device, comprising:
the display to be tested is used for displaying a preset test pattern;
the camera is used for generating a shooting image of the display to be tested under the first exposure time length and the second exposure time length respectively; the photographed image includes the test pattern;
a server, respectively connected to the tested display and the camera, for obtaining the halo value of the halo area around the test pattern by using the halo measuring method for display device according to any one of claims 1-8, so as to evaluate the halo of the tested display by the halo value.
10. The halo measurement system for a display device according to claim 9, wherein a ratio of an area of the test pattern to a display area of the display under test is less than or equal to 10%.
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