Method and device for testing horizontal decomposition force of mining camera

Abstract

The invention discloses a method and a device for testing the horizontal resolution of a mining camera, and belongs to the technical field of camera performance evaluation and test.The testing method comprises the following steps: electrically starting, and aligning a to-be-tested mining camera with a test graphic card in a camera obscura; configuring automatic testing software, and starting testing after configuration is completed; adjusting the brightness of the light source to enable the illuminance in the camera obscura to reach a specified value, and monitoring the illuminance by using an illuminance sensor; the mine camera is started, the tested mine camera is focused on the test graphic card, and the camera shoots and collects an image of the test graphic card after focusing is completed; analyzing and processing the acquired image, and calculating to obtain a horizontal decomposition force of the camera under a specified illumination condition; and repeatedly adjusting the brightness of the light source, obtaining and analyzing a complete data set, and outputting a test report. The device is suitable for testing the horizontal decomposition force of the mining camera in the low-illumination environment, can accurately measure the horizontal decomposition force of the camera in the actual use environment of a mine, and makes up for the defects in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of camera performance evaluation and testing, and in particular to a method and a device for testing the horizontal resolution of a mining camera. Background Art

[0002] Mining cameras play a key role in mine safety production monitoring. They can monitor the operation conditions in the mine in real time and ensure the safety of miners. Due to the complex environment of mines, the illumination is generally low, usually between 50-300 lux. Therefore, the imaging quality of cameras under low illumination conditions is particularly important.

[0003] At present, horizontal resolution is a key indicator to measure the camera's ability to resolve horizontal details, which directly affects the clarity of the monitoring image.

[0004] For example, the prior art (CN114079768B) provides a method and device for testing the clarity of an image, which involves obtaining a panoramic image and multiple single-view images collected by a panoramic surround view system, wherein the panoramic image is an image obtained by stitching multiple single-view images, and each single-view image includes a picture card located at a test point; the picture card included in each single-view image is analyzed for clarity to obtain the single-view clarity corresponding to each test point, and the picture card included in the panoramic image is analyzed for clarity to obtain the panoramic clarity corresponding to each test point. However, most of the existing testing methods are aimed at testing the horizontal resolution of cameras under ordinary lighting conditions, and lack special testing methods and devices for low-light environments in coal mines, resulting in the inability to accurately evaluate the horizontal resolution of cameras in low-light environments, and the testing process is complicated and the reliability of the results is low; it also fails to meet the special use environment of mining cameras and cannot effectively simulate the actual lighting conditions in the mine, affecting the practicality of the test results.

[0005] Therefore, there is an urgent need for a method for detecting the horizontal resolution of a mining camera under low illumination conditions. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention aims to provide an automated testing method and device for the horizontal resolution of mining cameras suitable for low illumination environments of 50-300 lux, which can accurately measure the horizontal resolution of the camera in the actual use environment of the mine, and make up for the deficiencies of the prior art.

[0007] The present invention adopts the following technical solution.

[0008] The first aspect of the present invention discloses a method for testing the horizontal resolution of a mining camera, comprising the following steps:

[0009] Start the machine electrically and aim the mining camera to be tested at the test chart in the dark box;

[0010] Configure automated testing software: perform system configuration and test task configuration, and start testing after configuration is completed;

[0011] Adjust the brightness of the light source so that the illumination in the dark box reaches the specified value, and use a low-light illuminance meter to monitor the illumination;

[0012] Start the mining camera, and focus the tested mining camera on the test chart. After focusing, the camera shoots and collects the image of the test chart;

[0013] Analyze and process the collected images to calculate the horizontal resolution of the camera under specified illumination conditions;

[0014] Repeatedly adjust the brightness of the light source, perform tests under different illumination levels, obtain and analyze complete data sets, and output test reports.

[0015] Preferably, the system is configured to check hardware configuration and connection relationship;

[0016] The test task configuration includes: setting the test illumination, test distance, chart type and decision threshold.

[0017] Preferably, the specified value of the illumination in the dark box is 50-300 lux.

[0018] Preferably, the calculating of the horizontal resolution under the specified illumination conditions specifically includes:

[0019] The calculation of the horizontal resolution under the specified illumination conditions specifically includes:

[0020] Image frequency response analysis: The acquired image is converted from the spatial domain to the frequency domain through image analysis software, and the frequency components of the image are extracted using Fourier transform to obtain the amplitude spectrum of the image;

[0021] Modulation transfer function calculation: After obtaining the amplitude spectrum of the image, the modulation transfer function is calculated to obtain the modulation transfer function curve;

[0022] Spatial frequency response calculation: The spatial frequency response curve is derived from the calculated modulation transfer function curve;

[0023] Calculation of horizontal resolution: Calculate the horizontal resolution based on the 50% modulation transfer function value in the spatial frequency response curve.

[0024] Preferably, the modulation transfer function is calculated by dividing the image intensity at the frequency f acquired by the image analysis software by the maximum intensity of the acquired image.

[0025] Preferably, the spatial frequency response is calculated by dividing the image contrast at frequency f acquired by image analysis software by the maximum contrast of the acquired image at low frequency.

[0026] Preferably, the horizontal resolution is calculated by measuring the spatial frequency corresponding to when the modulation transfer function curve reaches 50%, and obtaining the inverse thereof to obtain the horizontal resolution.

[0027] Preferably, the analysis of the obtained data set comprises:

[0028] Establish a model: summarize the horizontal resolution data under different illuminations and draw a curve of the relationship between the horizontal resolution of the camera and the illumination;

[0029] Performance evaluation: Analyze the performance of the camera in low-light environments based on the curve, evaluate the product and provide a basis for its improvement.

[0030] The second aspect of the present invention discloses a device for testing the horizontal resolution of a mining camera, which executes the method for testing the horizontal resolution of a mining camera, and includes a testing module and an analysis module;

[0031] The test module includes: a dark box, an adjustable light source, a test chart and an illumination sensor, and is used to test the mining camera;

[0032] The analysis module includes a computer for analyzing the data obtained by the test module.

[0033] Preferably, the adjustable light source and the test chart are arranged inside the dark box, and a light intensity sensor is installed outside the dark box, and the adjustable light source and the light intensity sensor are respectively connected to a computer;

[0034] The mining camera is connected to a computer, arranged outside the dark box and aligned with a test chart in the dark box.

[0035] Compared with the prior art, the beneficial effects of the present invention include at least:

[0036] 1. Dark box design for low-light simulation environment: The specially designed dark box can accurately simulate the low-light environment of 50-300 lux in the mine, eliminate the interference of ambient light, provide stable test conditions, and accurately measure the horizontal resolution of mining cameras under low-light conditions, filling the gap in existing technology.

[0037] 2. Automated testing system: Equipped with automated software to complete the entire testing process without manual intervention, significantly improving efficiency and accuracy; formulating standardized automatic testing processes to enhance the repeatability and reliability of test results and reduce errors caused by manual intervention.

[0038] 3. Adjustable precise light source system: Use LED light source with adjustable brightness, combined with high-precision light intensity sensor, to achieve precise control of illumination.

[0039] 4. Standardized test process: A horizontal resolution test process suitable for low-light conditions has been developed to improve the repeatability and reliability of the test results.

[0040] 5. Optimize product performance: Through accurate test data, help manufacturers improve camera design and enhance product imaging quality in low-light environments.

[0041] 6. Enhance safety assurance: Improve the monitoring effect of mining cameras, provide strong support for mine safety production, and reduce the occurrence of safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the overall structure of the test device;

[0043] Figure 2 This is a schematic diagram of the internal layout of the dark box;

[0044] Figure 3 It is a test flow chart;

[0045] In the figure: 1- camera under test; 2- dark box; 3- adjustable light source; 4- light intensity sensor; 5- computer. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0047] Embodiment 1 of the present invention provides a method for testing the horizontal resolution of a mining camera under low illumination conditions. Figure 3 As shown, the specific steps include:

[0048] Step 1: Connect the hardware equipment, power on each module, ensure that all experimental equipment is connected normally, and align the mining camera to be tested with the test chart in the dark box;

[0049] Step 2: Configure the automated test software: First, configure the system to check whether the hardware configuration and connection are successful; then configure the test task, including setting the test illumination, test distance, chart type, and judgment threshold; after the configuration is completed, start the test;

[0050] Step 3: Use automated software to adjust the brightness of the light source so that the illumination in the dark box reaches the specified value (such as 50 lux); use a light sensor to monitor the illumination and ensure the accuracy of the illumination by finely adjusting the light source power;

[0051] Step 4: Start the camera through the automation software, focus the camera on the test chart accurately, confirm that the focus is complete, and control the camera through the automation software to capture the image of the test chart;

[0052] Step 5: Use the test software installed on the industrial computer to analyze and process the acquired images, and calculate the horizontal resolution of the camera under the current illumination conditions.

[0053] The specific calculation steps in step 5 are as follows:

[0054] 1. Image frequency response analysis:

[0055] The acquired image is converted from the spatial domain to the frequency domain through image analysis software, and the frequency components of the image are extracted using Fourier transform to obtain the amplitude spectrum of the image.

[0056] Fourier transform can separate the information of different spatial frequencies in the image, thereby quantifying the contribution of different frequencies to the image quality. In the frequency domain, the frequency components of the image are presented as an amplitude spectrum, which represents the intensity distribution of the image at different frequencies. This step is crucial for evaluating the high-frequency response of the image, because the high-frequency components represent the details and resolution in the image.

[0057] 2. Modulation transfer function calculation:

[0058] After obtaining the amplitude spectrum of the image, the modulation transfer function is further calculated to obtain the modulation transfer function curve.

[0059] Modulation transfer function is one of the key indicators for image quality assessment, which reflects the modulation capability of the image system at different spatial frequencies.

[0060] The modulation transfer function is calculated by dividing the image intensity at the frequency f acquired by the image analysis software by the maximum intensity of the acquired image.

[0061] Among them, the image intensity at frequency f indicates the clarity of the image at this frequency; the maximum intensity of the image is usually the intensity of the low-frequency part. At different frequencies, the modulation transfer function describes the degree of image contrast preservation. The closer the modulation transfer function value is to 1, the higher the clarity of the image; conversely, the smaller the modulation transfer function value, the blurrier the image.

[0062] 3. Spatial frequency response calculation:

[0063] The spatial frequency response curve can be further derived from the calculated modulation transfer function curve.

[0064] The spatial frequency response curve represents the contrast response capability of an image at different spatial frequencies and is a direct expression of the resolution of the image system.

[0065] The spatial frequency response is calculated by dividing the image contrast at frequency f acquired by the image analysis software by the maximum contrast of the image at low frequency. The spatial frequency response curve provides a ratio for each frequency, reflecting the clarity of the image at that frequency.

[0066] 4. Calculation of horizontal resolution:

[0067] The horizontal resolution is further calculated based on the 50% modulation transfer function value in the spatial frequency response curve.

[0068] Horizontal resolution refers to the smallest detail that an imaging system can resolve, usually measured in line pairs per millimeter (lp / mm).

[0069] By measuring the spatial frequency corresponding to when the modulation transfer function curve reaches 50%, the horizontal resolution is obtained by obtaining its reciprocal.

[0070] The principle is to deduce the minimum detail spacing that the system can clearly resolve by measuring the spatial frequency corresponding to the modulation transfer function curve reaching 50%. At this time, the 50% modulation transfer function value represents the boundary of the system resolution, that is, the point where the image clarity has reached half, which is usually used to define the effective resolution of the system.

[0071] Through the above steps, important resolution indicators can be effectively extracted from image data to help accurately evaluate the horizontal resolution of equipment such as cameras. This analysis method can not only help understand the performance of the image system, but also provide quantitative data support for optimizing equipment performance and improving image quality;

[0072] Step 6: Repeat steps 2-5, test under different illuminations, obtain and analyze the complete data set, and output the test report;

[0073] Performing data analysis on the data set, including:

[0074] Step 6.1, establish a model: summarize the horizontal resolution data under different illuminations, and draw a curve of the relationship between the horizontal resolution of the camera and the illumination;

[0075] Step 6.2, performance evaluation: Analyze the performance of the camera in low-light environments based on the curve, evaluate the product and provide a basis for its improvement.

[0076] The evaluation method described:

[0077] Horizontal resolution: According to GAT 1127-2013 General Technical Requirements for Security Video Surveillance Cameras, evaluate whether the horizontal resolution of the camera under different illumination conditions meets the requirements of the corresponding camera category (such as HD, SD, etc.). For example, the horizontal resolution of a HD camera should be above HD.

[0078] Minimum usable illumination: Evaluates whether the camera can maintain 70% of its nominal resolution under low illumination conditions such as 50 lux to ensure its imaging quality in low-light environments.

[0079] Curve analysis of the camera's performance in low-light environments provides a basis for product improvement.

[0080] The improvement suggestions are:

[0081] Improved image clarity: Based on the horizontal resolution performance under different illumination conditions in the evaluation, it is recommended that manufacturers improve optical components and algorithms to improve resolution in low illumination (such as below 50 lux).

[0082] Low illumination adaptability: If the camera performs poorly in the minimum usable illumination test, it is recommended to use improved backlight compensation and automatic gain control functions to enhance the ability to restore image details in low light conditions to ensure compliance with the minimum usable illumination classification requirements in GAT1127-2013.

[0083] Under laboratory conditions, a certain brand of mining camera was tested using the test device of the present invention, and the specific process is as follows:

[0084] Preparation: Place the dark box in a dark environment, connect the hardware equipment and configure the automation software to ensure that all experimental equipment is connected normally.

[0085] Testing process:

[0086] Step 1: Set the illumination to the specified value, and the system will automatically operate throughout the process, collect images, and record the horizontal resolution value;

[0087] Step 2: Through automated control, test at different illumination levels, obtain and analyze complete data sets, and automatically repeat acquisition and recording.

[0088] Result analysis:

[0089] According to the GAT 1127-2013 standard, the horizontal resolution and minimum available illumination of the camera under low illumination conditions are evaluated, including whether it meets the requirements of high-definition categories under different illuminations, and whether it can maintain 70% of the nominal resolution under conditions such as 50lux. Through curve analysis of the performance of the camera in low illumination environments, it is recommended to improve the optical components and algorithms to improve the resolution under low illumination; at the same time, optimize the backlight compensation and automatic gain control functions to enhance the ability to restore image details in low-light environments.

[0090] like Figure 1-2 As shown, embodiment 2 of the present invention provides an automated testing device for testing the horizontal resolution of a mining camera under low illumination conditions, including a testing module and an analysis module;

[0091] The test module includes: a dark box, an adjustable light source, a test chart and an illumination sensor, and is used to test the mining camera;

[0092] The analysis module includes a computer for analyzing the data obtained by the test module.

[0093] The test device specifically comprises: a dark box 2, an adjustable light source 3, a standard test chart, a light intensity sensor 4, a test computer 5, test software and automation software.

[0094] The dark box 2 is a dark box with a matte black coating inside to eliminate interference from ambient light. The internal size of the dark box is sufficient to accommodate a standard test chart and an adjustable light source 3.

[0095] The light source is a light source with adjustable brightness (such as an LED light source), and the illumination is accurately controlled within the range of 50-300 lux by the automation software of the computer 5 .

[0096] The standard test chart is a resolution test chart that complies with the ISO 12233 standard and is used to evaluate the horizontal resolution of a camera.

[0097] A high-precision light intensity sensor 4 is installed near the test chart, and the sensor can be controlled by the automation software of the computer 5 to measure and monitor the illumination in the dark box.

[0098] The camera 1 under test is aligned with the test chart in the dark box 2 and is connected to the computer 5 .

[0099] Compared with the prior art, the beneficial effects of the present invention include at least:

[0100] 1. Dark box design for low-light simulation environment: The specially designed dark box can accurately simulate the low-light environment of 50-300 lux in the mine, eliminate the interference of ambient light, provide stable test conditions, and accurately measure the horizontal resolution of mining cameras under low-light conditions, filling the gap in existing technology.

[0101] 2. Adjustable precise light source system: Use LED light source with adjustable brightness, combined with high-precision light sensor and automation software to achieve precise control of illumination.

[0102] 3. Automated testing system: Equipped with automated software to complete the entire test without manual intervention, significantly improving efficiency and accuracy; formulating standardized automatic testing processes to enhance the repeatability and reliability of test results and reduce errors caused by manual intervention.

[0103] 4. Optimize product performance: Through accurate automated test data, help manufacturers improve camera design and improve product imaging quality in low-light environments.

[0104] 5. Enhanced safety assurance: Improve the monitoring effect of mining cameras, provide strong support for mine safety production, and reduce the occurrence of safety accidents.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for testing the horizontal resolution of a mining camera, characterized in that: The following steps are involved: Start the machine electrically and aim the mining camera to be tested at the test chart in the dark box; Configure automated testing software: perform system configuration and test task configuration, and start testing after configuration is completed; Adjust the brightness of the light source so that the illumination in the dark box reaches the specified value, and use a light sensor to monitor the illumination; Start the mining camera, and focus the tested mining camera on the test chart. After focusing, the camera shoots and collects the image of the test chart; Analyze and process the collected images to calculate the horizontal resolution of the camera under specified illumination conditions; Repeatedly adjust the brightness of the light source, perform tests under different illumination levels, obtain and analyze complete data sets, and output test reports.

2. The method for testing the horizontal resolution of a mining camera according to claim 1, characterized in that: The system is configured to check hardware configuration and connection relationship; The test task configuration includes: setting the test illumination, test distance, chart type and decision threshold.

3. The method for testing the horizontal resolution of a mining camera according to claim 1, characterized in that: The specified value of the illumination in the dark box is 50-300 lux.

4. The method for testing the horizontal resolution of a mining camera according to claim 1, characterized in that: The calculation of the horizontal resolution under the specified illumination conditions specifically includes: Image frequency response analysis: The acquired image is converted from the spatial domain to the frequency domain through image analysis software, and the frequency components of the image are extracted using Fourier transform to obtain the amplitude spectrum of the image; Modulation transfer function calculation: After obtaining the amplitude spectrum of the image, the modulation transfer function is calculated to obtain the modulation transfer function curve; Spatial frequency response calculation: The spatial frequency response curve is derived from the calculated modulation transfer function curve; Calculation of horizontal resolution: Calculate the horizontal resolution based on the 50% modulation transfer function value in the spatial frequency response curve.

5. The method for testing the horizontal resolution of a mining camera according to claim 3, characterized in that: The modulation transfer function is calculated by dividing the image intensity at the frequency f acquired by the image analysis software by the maximum intensity of the acquired image.

6. The method for testing the horizontal resolution of a mining camera according to claim 3, characterized in that: The spatial frequency response is calculated by dividing the image contrast at frequency f acquired by image analysis software by the maximum contrast of the acquired image at low frequency.

7. The method for testing the horizontal resolution of a mining camera according to claim 3, characterized in that: The horizontal resolution is calculated by measuring the spatial frequency corresponding to when the modulation transfer function curve reaches 50%, and obtaining the inverse thereof to obtain the horizontal resolution.

8. The method for testing the horizontal resolution of a mining camera according to claim 1, characterized in that: The analysis of the obtained data set includes: Establish a model: summarize the horizontal resolution data under different illuminations and draw a curve of the relationship between the horizontal resolution of the camera and the illumination; Performance evaluation: Analyze the performance of the camera in low-light environments based on the curve, evaluate the product and provide a basis for its improvement.

9. A device for testing the horizontal resolution of a mining camera, which implements a method for testing the horizontal resolution of a mining camera according to any one of claims 1 to 8, characterized in that: Includes test module and analysis module; The test module includes: a dark box, an adjustable light source, a test chart and an illumination sensor, and is used to test the mining camera; The analysis module includes a computer for analyzing the data obtained by the test module.

10. A device for testing the horizontal resolution of a mining camera according to claim 9, characterized in that: The adjustable light source and the test chart are arranged inside the dark box, and a light intensity sensor is installed outside the dark box. The adjustable light source and the light intensity sensor are respectively connected to a computer; The mining camera is connected to a computer, arranged outside the dark box and aligned with a test chart in the dark box.

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