A terminal screen display sight mark calibration method and vision detection system

Abstract

The present invention provides a method for calibrating a visual mark displayed on a terminal screen and a vision detection system. The calibration method first generates a reference line segment of a specified pixel on the terminal screen, and then uses a physical ruler to adjust and calibrate the reference line segment displayed on the screen by increasing or decreasing the pixels one by one, until the display length of the reference line segment reaches a specific size marked by the ruler, and then substitutes the pixel adjustment ratio into the conversion formula of the visual mark size for conversion, thereby obtaining the accurate size of the visual mark displayed on the terminal screen. This calibration method does not need to obtain the accurate screen density of the terminal screen, and is not affected by factors such as the manufacturing process of the terminal screen. The calculation is accurate and easy to implement. The vision detection system using this method can ensure that the size of the visual mark seen during the vision detection is consistent with the size of the visual mark seen by other users on their respective terminal screens, thereby effectively ensuring that the vision results detected by the vision detection system on different terminals are consistent and comparable.

Description

Technical Field

[0001] The invention relates to a sight mark calibration method and a vision detection system, in particular to a method for calibrating the size of a sight mark when a terminal screen displays the sight mark and a vision detection system using the method, belonging to the technical field of vision detection. Background Art

[0002] Conventional vision testing uses a fixed standard vision chart for testing. During the test, the person being tested needs to stand at a certain distance from the vision chart. The tester points to a certain sight mark on the vision chart with a pointer. The person being tested gives feedback on the direction of the sight mark opening to the tester, who then makes a comparison and judgment to finally get the person's vision value. In this method, the sight mark arrangement of the vision chart is fixed, and the person being tested can easily cheat by memorizing it temporarily, resulting in inaccurate test results. In addition, most vision charts are light box or projection type, which are inconvenient to carry.

[0003] For this reason, some new vision testing systems based on the visual mark displayed on the terminal screen have appeared on the market. They use electronically displayed visual marks, which can be displayed on a variety of terminal screens such as monitors and mobile phones. They are easy to carry and can randomly adjust the arrangement order of the visual marks, eliminating the possibility of cheating by memorizing. However, when matching different display terminals, such new vision testing systems have a serious problem that the size of the visual marks displayed on the screen is not uniform due to the different resolutions of the terminal screens. As a result, the developed vision testing system cannot be applied to different terminals for vision testing at all, because the final result of the test will cause a large error, which makes the test data between users completely lose comparability. At present, some new vision testing systems have also noticed this problem. They automatically calculate the display size of the visual mark on the terminal screen according to the nominal screen density of the terminal screen and the theoretical calculation formula to ensure that the size of the visual mark displayed on different terminal screens is consistent. However, in actual application, we found that this method still has certain defects. For example, it is not easy to directly obtain the nominal screen density of some terminal screens. Some terminal screens are affected by many factors such as manufacturing process. There is a certain error between the visual mark display size directly calculated according to the nominal screen density and theoretical calculation formula and the actual measured physical size. Therefore, the size of the visual mark displayed on different terminal screens cannot be completely consistent. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for calibrating the size of an optotype when the terminal screen displays an optotype and a vision detection system using the method. The calibration method uses a physical ruler as an auxiliary standard to adjust and calibrate the reference line segments displayed on the screen by increasing or decreasing pixels one by one, and then substitutes the pixel adjustment ratio into the conversion formula of the optotype size for conversion, thereby obtaining the accurate size of the optotype displayed on the terminal screen. The vision detection system using this method can ensure that the size of the optotype seen during the vision test is consistent with the size of the optotype seen by other users on their respective terminal screens, thereby effectively ensuring that the vision results detected by the vision detection system on different terminals are consistent and comparable.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] A method for calibrating a visual mark displayed on a terminal screen comprises the following steps:

[0007] Step 1: Generate a reference line segment of specified pixels on the terminal screen, where the display length of the reference line segment is 1 cm at a given resolution.

[0008] Step 2: Use a physical ruler to measure the length of the reference line segment on the terminal screen, and then adjust the length of the reference line segment by manually increasing or decreasing pixels so that the displayed length of the reference line segment on the terminal screen reaches 1 cm as indicated by the ruler.

[0009] Step 3: Convert the size of the built-in standard sight mark according to the pixel adjustment ratio of the reference line segment to obtain the sight mark size of the terminal screen. The conversion formula is:

[0010] D′ = D * λ

[0011] Where: D′ is the visual mark size of the terminal screen;

[0012] D is the size of the built-in standard sight mark, that is, the standard sight mark size for each level of vision at a given resolution and a given test distance;

[0013] λ is the pixel after adjustment / pixel before adjustment of the reference line segment.

[0014] A vision detection system using a terminal screen to display an optotype, when using the terminal screen to display an optotype for vision detection, the display size of the terminal screen optotype is calibrated using the above calibration method. The vision detection system specifically refers to a system that runs on various electronic terminals and uses the terminal screen to display an optotype for vision detection; the electronic terminal includes a PC terminal and a mobile phone terminal.

[0015] The specific calibration process of the vision detection system when using the visual mark displayed on the terminal screen includes the following steps:

[0016] Step S01, register / log in to the vision testing system, and establish a hardware information file for the terminal screen used to display the visual mark.

[0017] In step S02, each time the system uses the terminal screen to display the sight mark, it checks the hardware information of the terminal screen to determine whether the terminal screen is used to display the sight mark for the first time; if the terminal screen is used to display the sight mark for the first time, it automatically enters the initial calibration window for initial calibration; if the terminal screen is not used to display the sight mark for the first time, it directly goes to step S09.

[0018] Step S03, performing initial calibration on the terminal screen in an initial calibration window displayed on the terminal screen; the initial calibration window is provided with a reference line segment of specified pixels, a plurality of calibration adjustment buttons and a calibration confirmation button, the display length of the reference line segment at a given resolution is 1 cm, and the calibration adjustment button is used to adjust the increase or decrease of pixels of the reference line segment to adjust the display length of the reference line segment; the length of the reference line segment is measured on the terminal screen with a physical ruler.

[0019] Step S04: If the reference line segment displayed on the terminal screen exceeds the 1 cm length marked on the ruler, the pixels are reduced by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler.

[0020] Step S05: If the reference line segment displayed on the terminal screen is less than the 1 cm length marked on the ruler, increase the pixels by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler.

[0021] Step S06, when the displayed length of the reference line segment is adjusted to the 1 cm length indicated by the ruler, press the calibration confirmation button to confirm the calibration, thereby completing the calibration of the reference line segment.

[0022] Step S07: After the calibration is confirmed, the system automatically uploads the calibration data of the terminal screen to the data storage module for storage.

[0023] In step S08, the calibration conversion module of the system reads the corresponding built-in standard sight mark size from the data storage module according to the test distance input by the user, then reads the calibration data of the terminal screen from the data storage module, and then automatically converts according to the conversion formula to obtain the calibrated terminal screen sight mark size.

[0024] The conversion formula is:

[0025] D′ = D * λ

[0026] Where: D′ is the visual mark size of the terminal screen;

[0027] D is the size of the built-in standard sight mark, i.e., the standard sight mark size for each level of vision under the conditions of a given resolution and a given test distance pre-stored in the data storage module;

[0028] λ is the pixel after adjustment / pixel before adjustment of the reference line segment, which is obtained from the calibration data of the terminal screen.

[0029] In step S09, the system controls to automatically cache the converted sight marks of each level of vision in the terminal according to the calibrated size, so that the sight marks can be quickly displayed on the terminal screen during vision testing.

[0030] The beneficial effects of the present invention are as follows: the calibration method of the visual mark displayed on the terminal screen of the present invention uses a physical ruler as an auxiliary standard to adjust and calibrate the reference line segments displayed on the screen by increasing or decreasing pixels one by one, and then substitutes the pixel adjustment ratio into the conversion formula of the visual mark size for conversion, thereby obtaining the accurate size of the visual mark displayed on the terminal screen. This calibration method does not need to obtain the accurate screen density of the terminal screen, nor is it affected by factors such as the manufacturing process of the terminal screen. The calculation is accurate and easy to implement. The vision detection system using this method can ensure that the size of the visual mark seen during the vision detection is consistent with the size of the visual mark seen by other users on their respective terminal screens, thereby effectively ensuring that the vision results detected by the vision detection system on different terminals are consistent and comparable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a specific calibration flow chart of the vision detection system when using the visual mark displayed on the terminal screen.

[0032] Figure 2 It is a schematic diagram of performing initial calibration on the terminal screen in the initial calibration window. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] The method for calibrating a terminal screen display sight mark of the present invention comprises the following steps:

[0035] Step 1: Generate a reference line segment of specified pixels on the terminal screen, where the display length of the reference line segment is 1 cm at a given resolution.

[0036] Preferably, the designated pixel is 118.11 pixels and the given resolution is 300 dpi. Because 300 dpi = 300 pixels / inch, 1 inch = 2.54 centimeters, 300 pixels / inch = 118.11 pixels / centimeter, so the display length of the reference line segment of 118.11 pixels at a resolution of 300 dpi is 1 cm.

[0037] Step 2: Use a physical ruler to measure the length of the reference line segment on the terminal screen, and then adjust the length of the reference line segment by manually increasing or decreasing pixels so that the displayed length of the reference line segment on the terminal screen reaches 1 cm as indicated by the ruler.

[0038] Step 3: Convert the size of the built-in standard sight mark according to the pixel adjustment ratio of the reference line segment to obtain the sight mark size of the terminal screen. The conversion formula is:

[0039] D′ = D * λ

[0040] Where: D′ is the visual mark size of the terminal screen;

[0041] D is the size of the built-in standard sight mark, that is, the standard sight mark size for each level of vision at a given test distance and resolution;

[0042] λ is the pixel after adjustment / pixel before adjustment of the reference line segment.

[0043] A vision detection system using a terminal screen to display an optotype, when using the terminal screen to display an optotype for vision detection, the display size of the terminal screen optotype is calibrated using the above calibration method. The vision detection system specifically refers to a system that runs on various electronic terminals and uses the terminal screen to display an optotype for vision detection; the electronic terminal includes a PC terminal and a mobile phone terminal.

[0044] like Figure 1-2 As shown, the specific calibration process of the vision detection system when using the visual mark displayed on the terminal screen includes the following steps:

[0045] Step S01, register / log in to the vision testing system, and establish a hardware information file for the terminal screen used to display the visual mark.

[0046] In step S02, each time the system uses the terminal screen to display the sight mark, it checks the hardware information of the terminal screen to determine whether the terminal screen is used to display the sight mark for the first time; if the terminal screen is used to display the sight mark for the first time, it automatically enters the initial calibration window for initial calibration; if the terminal screen is not used to display the sight mark for the first time, it directly goes to step S09.

[0047] Step S03, performing initial calibration on the terminal screen in an initial calibration window displayed on the terminal screen; the initial calibration window is provided with a reference line segment of specified pixels, a plurality of calibration adjustment buttons and a calibration confirmation button, the display length of the reference line segment at a given resolution is 1 cm, and the calibration adjustment button is used to adjust the increase or decrease of pixels of the reference line segment to adjust the display length of the reference line segment; the length of the reference line segment is measured on the terminal screen with a physical ruler.

[0048] Preferably, the designated pixels are 118.11 pixels, the given resolution is 300 dpi, and the display length of the reference line segment of 118.11 pixels at a resolution of 300 dpi is 1 cm.

[0049] Preferably, the calibration adjustment button is provided with a "-1 pixel" button and a "+1 pixel" button for precise calibration, and is also provided with a "-5 pixel" button and a "+5 pixel" button for quick calibration.

[0050] Step S04: If the reference line segment displayed on the terminal screen exceeds the 1 cm length marked on the ruler, the pixels are reduced by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler.

[0051] Step S05: If the reference line segment displayed on the terminal screen is less than the 1 cm length marked on the ruler, increase the pixels by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler.

[0052] Step S06, when the displayed length of the reference line segment is adjusted to the 1 cm length indicated by the ruler, press the calibration confirmation button to confirm the calibration, thereby completing the calibration of the reference line segment.

[0053] Step S07: After the calibration is confirmed, the system automatically uploads the calibration data of the terminal screen to the data storage module for storage.

[0054] In step S08, the calibration conversion module of the system reads the corresponding built-in standard sight mark size from the data storage module according to the test distance input by the user, then reads the calibration data of the terminal screen from the data storage module, and then automatically converts according to the conversion formula to obtain the calibrated terminal screen sight mark size.

[0055] The conversion formula is:

[0056] D′ = D * λ

[0057] Where: D′ is the visual mark size of the terminal screen;

[0058] D is the size of the built-in standard sight mark, i.e., the standard sight mark size for each level of vision under the conditions of a given test distance and a given resolution pre-stored in the data storage module;

[0059] λ is the pixel after adjustment / pixel before adjustment of the reference line segment, which is obtained from the calibration data of the terminal screen.

[0060] The D value in the above conversion formula can be determined according to the provisions of the national standard GB 11533-2011 on logarithmic visual acuity chart and the formula for calculating the size of the sight mark D = παd / 10800 given in "Research on Computer Intelligent Vision Measurement System" (Computer Knowledge and Technology Vol.6, No.18, June 2010, pp.5034-5035), where d is the test distance. For example, under the conditions of a test distance d of 2000mm and a resolution of 300dpi:

[0061] The standard sight mark size corresponding to vision level 5.3 is D=π*0.501′*2000 / 10800=0.29mm=3.4 pixels; the standard sight mark size corresponding to vision level 5.2 is D=π*0.631′*2000 / 10800=0.37mm=4.37 pixels; the standard sight mark size corresponding to vision level 5.1 is D=π*0.794′*2000 / 10800=0.46mm=5.43 pixels; the standard sight mark size corresponding to vision level 5.0 is D=π*1.000′*20 00 / 10800=0.58mm=6.85 pixels; the standard sight mark size corresponding to the visual acuity level of 4.9 is D=π*1.259′*2000 / 10800=0.73mm=8.62 pixels; the standard sight mark size corresponding to the visual acuity level of 4.8 is D=π*1.585′*2000 / 10800=0.92mm=10.87 pixels; the standard sight mark size corresponding to the visual acuity level of 4.7 is D=π*1.995′*2000 / 10800=1.16mm=13.70 pixels; visual acuity, etc. The standard sight mark size corresponding to vision level 4.6 is D=π*2.512′*2000 / 10800=1.46mm=17.24 pixels; the standard sight mark size corresponding to vision level 4.5 is D=π*3.162′*2000 / 10800=1.84mm=21.73 pixels; the standard sight mark size corresponding to vision level 4.4 is D=π*3.981′*2000 / 10800=2.32mm=27.40 pixels; the standard sight mark size corresponding to vision level 4.3 is D=π*5.012′*2 000 / 10800=2.92mm=34.49 pixels; the standard sight mark size corresponding to vision level 4.2 is D=π*6.310′*2000 / 10800=3.67mm=43.35 pixels; the standard sight mark size corresponding to vision level 4.1 is D=π*7.943′*2000 / 10800=4.62mm=54.57 pixels; the standard sight mark size corresponding to vision level 4.0 is D=π*10.000′*2000 / 10800=5.8mm=68.50 pixels.

[0062] The following takes the terminal screen of Huawei P50 mobile phone as an example to illustrate the conversion process of the conversion formula.

[0063] The screen resolution of the Huawei P50 phone is 2700 x 1224 pixels, and the body screen is 6.5 inches. A rough calculation of the PPI (pixel density) of the phone is ((2700)²+(1224)²) 0.5 / 6.5 = 456 dpi, which means there are 456 pixels per inch, or 456 pixels / inch = 179.53 pixels / cm.

[0064] In the previous steps, a reference line segment of 118.11 pixels is given in the initial calibration window. According to the proportional relationship, it is displayed as approximately 118.11*1 / 179.53=0.658cm on the screen of Huawei P50 (456dpi). The length of the reference line segment is measured on the terminal screen with a physical ruler. The user manually increases the pixels by operating the calibration adjustment button until the displayed length of the reference line segment = the 1cm length marked on the ruler. Assuming that the user has increased a total of 58 pixels, the reference line segment is 118.11+58=176.11 pixels at this time. It can be calculated that λ= 176.11 / 118.11=1.49; on the Huawei P50 mobile phone, the visual mark size D′ = D * λ=3.4*1.49=5.07 pixels corresponding to the visual acuity level 5.3, and the visual mark size D′ = D corresponding to the visual acuity level 5.2 *λ=4.37*1.49=6.51 pixels..., and so on, you can get a set of calibrated sight mark sizes for the Huawei P50 terminal screen.

[0065] In step S09, the system controls to automatically cache the converted sight marks of each level of vision in the terminal according to the calibrated size, so that the sight marks can be quickly displayed on the terminal screen during vision testing.

[0066] The above-mentioned figures are only typical embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calibrating a visual mark displayed on a terminal screen, characterized in that: The following steps are involved: Step 1, generating a reference line segment of a specified pixel on the terminal screen, the display length of the reference line segment at a given resolution is 1 cm; the specified pixel is 118.11 pixels, and the given resolution is 300 dpi; Step 2: Use a physical ruler to measure the length of the reference line segment on the terminal screen, and then adjust the length of the reference line segment by manually increasing or decreasing pixels so that the displayed length of the reference line segment on the terminal screen reaches 1 cm as indicated by the ruler; Step 3: Convert the size of the built-in standard sight mark according to the pixel adjustment ratio of the reference line segment to obtain the sight mark size of the terminal screen. The conversion formula is: D′ = D * λ Where: D′ is the visual mark size of the terminal screen; D is the size of the built-in standard sight mark, that is, the standard sight mark size for each level of vision at a given resolution and a given test distance; λ is the pixel after adjustment / pixel before adjustment of the reference line segment.

2. A vision detection system with visual signs displayed on the terminal screen, which refers specifically to a system that runs on various electronic terminals and performs vision detection by displaying visual signs on the terminal screen, characterized in that: When the vision detection system uses the terminal screen to display the sight mark for vision detection, the display size of the terminal screen sight mark is calibrated using the calibration method as described in claim 1.

3. The vision detection system with terminal screen display sight mark according to claim 2, characterized in that: The electronic terminals include PC terminals and mobile phone terminals.

4. The vision detection system with terminal screen display sight mark according to claim 2, characterized in that: The specific calibration process of the vision detection system when using the visual mark displayed on the terminal screen includes the following steps: Step S01, registering / logging into the vision testing system, and establishing a hardware information file of the terminal screen for displaying the sight mark; Step S02, each time the terminal screen is used to display the sight mark, the system checks the hardware information of the terminal screen to determine whether the terminal screen is used to display the sight mark for the first time; if the terminal screen is used to display the sight mark for the first time, the system automatically enters the initial calibration window for initial calibration; if the terminal screen is not used to display the sight mark for the first time, the system directly proceeds to step S09; Step S03, performing initial calibration on the terminal screen in the initial calibration window displayed on the terminal screen; the initial calibration window is provided with a reference line segment of a specified pixel, a plurality of calibration adjustment buttons and a calibration confirmation button, the display length of the reference line segment at a given resolution is 1 cm, the calibration adjustment button is used to adjust the increase or decrease of the pixels of the reference line segment to adjust the display length of the reference line segment; the length of the reference line segment is measured on the terminal screen with a physical ruler; the specified pixel is 118.11 pixels, and the given resolution is 300dpi; the calibration adjustment button is provided with a "-1 pixel" button and a "+1 pixel" button for precise calibration, and is also provided with a "-5 pixel" button and a "+5 pixel" button for quick calibration; Step S04: if the reference line segment displayed on the terminal screen exceeds the 1 cm length marked on the ruler, the pixels are reduced by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler; Step S05, if the reference line segment displayed on the terminal screen is less than the 1 cm length marked on the ruler, increase the pixels by manually operating the calibration adjustment button until the displayed length of the reference line segment equals the 1 cm length marked on the ruler; Step S06, when the displayed length of the reference line segment is adjusted to the 1 cm length indicated by the ruler, press the calibration confirmation button to confirm the calibration, and the calibration of the reference line segment is completed; Step S07, after the calibration is confirmed, the system automatically uploads the calibration data of the terminal screen to the data storage module for storage; Step S08, the calibration conversion module of the system reads the corresponding built-in standard sight mark size from the data storage module according to the test distance input by the user, then reads the calibration data of the terminal screen from the data storage module, and then automatically converts according to the conversion formula to obtain the calibrated terminal screen sight mark size; The conversion formula is: D′ = D * λ Where: D′ is the visual mark size of the terminal screen; D is the size of the built-in standard sight mark, i.e., the standard sight mark size for each level of vision under the conditions of a given resolution and a given test distance pre-stored in the data storage module; λ is the pixel after adjustment / pixel before adjustment of the reference line segment, obtained from the calibration data of the terminal screen; In step S09, the system controls to automatically cache the converted sight marks of each level of vision in the terminal according to the calibrated size, so that the sight marks can be quickly displayed on the terminal screen during vision testing.

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