A low contrast range testing device and method

Abstract

The present invention relates to a low-contrast action distance test device and method, wherein the device includes a test target source, an image acquisition processing component, a test model library construction module, an analysis module and a test module, which realizes the function of automatically detecting the resolution ability of a television camera system for low-contrast targets under different illuminations, and accurately evaluates the action distance of the television camera system under different atmospheric visibility. Compared with the prior art, the present invention is not restricted by the external environment, avoids the influence of errors caused by human subjective judgment, is simple and convenient to operate, has strong versatility, and has high test accuracy, and can effectively measure the action distance of the television camera system for low-contrast targets.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic equipment, and in particular to a low-contrast effective distance testing device and method. Background Art

[0002] Television camera systems are used in airborne or vehicle-mounted optoelectronic pods in defense and other fields. Their ability to accurately detect and identify long-distance and small targets is an important indicator of television camera systems. The test and evaluation of the television system's extreme resolution ability for long-distance targets under low-contrast conditions often requires actual field testing. Due to the influence of field weather conditions and visibility, the test is often difficult to carry out as scheduled.

[0003] Most of the existing equipment for testing the extreme detection capabilities of camera systems in laboratories adopts the method of replacing targets to adjust the contrast, and then the image of the product being tested is directly observed by the human eye. There is no feedback from the target source, and a large number of targets with different resolutions and contrasts need to be prepared. Continuous adjustment of contrast cannot be achieved, and there are large errors in human interpretation. It is also impossible to timely evaluate the effective distance of the product in different visibilities, and it is impossible to effectively measure the effective distance of the television camera system for low-contrast targets. Summary of the invention

[0004] In view of this, it is necessary to provide a low-contrast working distance testing device and method to solve the problem that the prior art cannot effectively measure the working distance of a television camera system for a low-contrast target.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a low contrast range test device, which is applied to a television camera system, comprising:

[0007] A test target source, wherein the contrast of the test target source is continuously adjustable;

[0008] An image acquisition and processing component, used for acquiring test samples of the test target source at different contrasts in the television camera system to be tested;

[0009] A test model library building module is used to establish multiple feature models with different contrasts and different spatial resolutions to form a feature model library;

[0010] An analysis module, used to obtain an action distance sample according to the test sample and the feature model library based on a preset analysis algorithm;

[0011] The test module is used to establish an atmospheric attenuation model and obtain test results according to the test sample, the action distance sample and the atmospheric attenuation model.

[0012] Furthermore, the test target source includes two integrating spheres, a positive target, a negative target, a target adjustment bracket and a beam combiner, wherein the positive target and the negative target are respectively arranged at the light output of the two integrating spheres, the patterns on the positive target and the negative target are the same as the background, the patterns of the positive target and the negative target overlap, and the beam combiner is located at the intersection of the light output of the two integrating spheres after passing through the positive target and the negative target.

[0013] Furthermore, it also includes an off-axis reflection device, which includes an off-axis parabolic primary reflector, a plane secondary mirror and a dichroic prism. The positive target and the negative target are both located at the conjugate focal plane of the off-axis reflection device. The off-axis reflection device is used to collimate the image formed by the test target source into an infinitely distant target.

[0014] In a second aspect, the present invention further provides a low contrast working distance test method, using the low contrast working distance test device as described above and applying it to a television camera system, the test method comprising:

[0015] Constructing a test target source, wherein the contrast of the test target source is continuously adjustable;

[0016] Establish multiple feature models with different contrasts and different spatial resolutions to form a feature model library;

[0017] Acquire test samples of the test target source at different contrasts in the television camera system to be tested;

[0018] According to the test sample and the feature model library, based on a preset analysis algorithm, an action distance sample is obtained;

[0019] Establish atmospheric attenuation model;

[0020] A test result is obtained according to the test sample, the action distance sample and the atmospheric attenuation model.

[0021] Furthermore, the establishment of multiple feature models with different contrasts and different spatial resolutions to form a feature model library includes:

[0022] Model construction: Establish multiple initial feature models with different contrasts and spatial resolutions;

[0023] Model sample acquisition: using the television camera system to be measured to acquire multiple model samples of the test target source;

[0024] Matching test: Match the initial feature model and the model sample. If the match is successful, use the multiple initial feature models as a feature model library. If the match fails, repeat the model construction and the model sample acquisition, and re-perform the matching test.

[0025] Furthermore, the test sample includes a sample image captured by the television camera system to be measured, and an illumination value and a contrast value corresponding to the sample image.

[0026] Furthermore, obtaining test samples of the test target source at different contrasts in the television camera system to be tested includes:

[0027] Obtain test samples;

[0028] The illumination value of the test sample is matched with the preset illumination value. If the match is successful, the test sample is retained. If the match fails, the test target source is adjusted and the test sample is acquired again.

[0029] Furthermore, obtaining the action distance sample according to the test sample and the feature model library based on a preset analysis algorithm includes:

[0030] According to the test sample, image information of the sample image is obtained;

[0031] Obtaining target features of the sample image according to the image information;

[0032] The target feature is matched with the feature model in the feature model library, and the action distance sample is obtained based on a preset analysis algorithm.

[0033] Furthermore, the image information includes pixel distribution, brightness and color of the sample image.

[0034] Furthermore, the atmospheric attenuation model includes:

[0035] I=I0*exp(-a*d)

[0036] Where I is the target light intensity, I0 is the initial light intensity, a is the absorption coefficient, and d is the light penetration depth.

[0037] The present invention provides a low-contrast action distance test device and method, which provide test targets with different test backgrounds, different contrasts, and different spatial frequencies by constructing a test target source with adjustable contrast. At the same time, a test model library construction module is used to establish a feature model library, and after obtaining test samples using an image acquisition and processing component, a distance sample is obtained through an analysis module, and the atmospheric attenuation model established by the test module is combined to obtain the final test result, thereby realizing the function of automatically detecting the resolution ability of a television camera system for low-contrast targets under different illuminations, and accurately evaluating the action distance of a television camera system under different atmospheric visibilities. Compared with the prior art, the present invention is not restricted by the external environment, avoids the influence of errors caused by human subjective judgment, is simple and convenient to operate, has strong versatility, and has high test accuracy, and can effectively measure the action distance of a television camera system for low-contrast targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic structural diagram of an embodiment of a low-contrast working distance testing device provided by the present invention;

[0039] Figure 2 A schematic diagram of a light beam between a test target source and an off-axis reflective type in a low-contrast range test device provided by the present invention;

[0040] Figure 3 The patterns of the positive target plate and the negative target plate provided by the present invention;

[0041] Figure 4 This is a method flow chart of an embodiment of a low-contrast working distance testing method provided by the present invention. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] In the description of the present application, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0044] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0045] The present invention provides a low-contrast working distance testing method and device, which are respectively described below.

[0046] Combination Figure 1 As shown, an embodiment of the present invention provides a low contrast working distance testing device, which can be applied to a television camera system, and is characterized in that it includes:

[0047] A test target source 1, wherein the contrast of the test target source is continuously adjustable;

[0048] An image acquisition and processing component 2 is used to obtain test samples of the test target source at different contrasts in the television camera system to be tested;

[0049] A test model library building module is used to establish multiple feature models with different contrasts and different spatial resolutions to form a feature model library;

[0050] An analysis module, used to obtain an action distance sample according to the test sample and the feature model library based on a preset analysis algorithm;

[0051] The test module is used to establish an atmospheric attenuation model and obtain test results according to the test sample, the action distance sample and the atmospheric attenuation model.

[0052] The present invention provides a low-contrast action distance test device and method, which provide test targets with different test backgrounds, different contrasts, and different spatial frequencies by constructing a test target source with adjustable contrast. At the same time, a test model library construction module is used to establish a feature model library, and after obtaining test samples using an image acquisition and processing component, a distance sample is obtained through an analysis module, and the atmospheric attenuation model established by the test module is combined to obtain the final test result, thereby realizing the function of automatically detecting the resolution ability of a television camera system for low-contrast targets under different illuminations, and accurately evaluating the action distance of a television camera system under different atmospheric visibilities. Compared with the prior art, the present invention is not restricted by the external environment, avoids the influence of errors caused by human subjective judgment, is simple and convenient to operate, has strong versatility, and has high test accuracy, and can effectively measure the action distance of a television camera system for low-contrast targets.

[0053] The test model library construction module, analysis module and test module in this embodiment can be implemented using existing devices with computing and storage functions, such as a CPU with memory, a microprocessor, a single-chip microcomputer, a computer storing a specific program, etc.

[0054] Specifically, combined Figure 2 and Figure 3In this embodiment, the test target source 1 includes two integrating spheres, a positive target, a negative target, a target adjustment bracket and a beam combiner, wherein the positive target and the negative target are respectively arranged at the light exits of the two integrating spheres, the patterns on the positive target and the negative target are the same as the background, the patterns of the positive target and the negative target overlap, and the beam combiner is located at the intersection of the light exits of the two integrating spheres after passing through the positive target and the negative target.

[0055] The positive and negative targets in the test target source 1 with adjustable contrast are combined into a composite target through a beam combiner. Since the composite target is composed of two independent targets, the target contrast can be adjusted by changing the illumination of any one of the targets. The integrating sphere adjusts the aperture of the electric diaphragm through its drive motor to achieve the purpose of controlling the illumination.

[0056] The dual integrating spheres used in this embodiment have an illumination acquisition and control module. When the illumination of one integrating sphere changes, the other integrating sphere will automatically adjust the light output illumination according to the set contrast value until the feedback value meets the contrast requirement.

[0057] Furthermore, the low contrast action distance test device in this embodiment also includes an off-axis reflection device 3, which is used for collimating the image formed by the test target source into an infinite target, including an off-axis parabolic primary reflector, a plane secondary mirror and a beam splitter prism, and the positive target and the negative target are both located at the conjugate focal plane of the off-axis reflection device. The secondary mirror folds the optical path to shorten the length of the device, and is convenient for setting other components or equipment at the focal plane; the beam splitter prism divides the main optical path into two paths, so as to arrange multiple devices at the focal plane. At the same time, the use of the beam splitter prism will not produce double images and will not reduce the imaging quality of the system.

[0058] Furthermore, the image acquisition and processing component 2 in this embodiment can be any device with control and computing capabilities such as a computer and a control terminal. The design analysis, calculation and decision-making steps in the above method are all executed in the image acquisition and processing component 2.

[0059] As a preferred embodiment, the low-contrast effective distance testing device in this embodiment also includes a testing platform 4, the test target source 1, the off-axis reflection device 3 and the image acquisition and processing component 2 are all connected to the testing platform 4, and the testing platform 4 is used to set up the television camera system to be tested.

[0060] Combination Figure 4 As shown, the present invention also provides a specific embodiment, disclosing a low contrast working distance test method, which is applied to test the low contrast working distance of a television camera system, and the method comprises:

[0061] S101, constructing a test target source, wherein the contrast of the test target source is continuously adjustable;

[0062] S102, establishing a plurality of feature models with different contrasts and different spatial resolutions to form a feature model library;

[0063] S103, obtaining test samples of the test target source at different contrasts in the television camera system to be tested;

[0064] S104, obtaining an action distance sample according to the test sample and the feature model library based on a preset analysis algorithm;

[0065] S105. Establish an atmospheric attenuation model;

[0066] S106: Obtain a test result according to the test sample, the action distance sample and the atmospheric attenuation model.

[0067] Specifically, as a preferred embodiment, step S102 in this embodiment, establishing multiple feature models with different contrasts and different spatial resolutions to form a feature model library, includes:

[0068] Model construction: Establish multiple initial feature models with different contrasts and spatial resolutions;

[0069] Model sample acquisition: using the television camera system to be measured to acquire multiple model samples of the test target source;

[0070] Matching test: match the initial feature model and the model sample. If the match is successful, use the multiple initial feature models as a feature model library. If the match fails, repeat the model construction and the model sample acquisition and re-perform the matching test.

[0071] The above process can make the established feature model library closest to the actual situation, thereby ensuring the accuracy of the measurement results.

[0072] As a preferred embodiment, in step S103 of this embodiment, the acquired test samples include sample images captured by the television camera system to be measured, illumination values ​​and contrast values ​​corresponding to the sample images, and the like.

[0073] Specifically, step S103 in this embodiment includes:

[0074] Obtain test samples;

[0075] The illumination value of the test sample is matched with the preset illumination value. If the match is successful, the test sample is retained. If the match fails, the test target source is adjusted and the test sample is acquired again.

[0076] When using the test target source to obtain the test sample, you can first set the required illuminance value in the control terminal such as the computer, that is, the preset illuminance value, and then collect a test sample for the experiment to obtain the illuminance value in the current environment, and then match it with the set illuminance value. If the collected illuminance value is consistent with the preset illuminance value, the analysis is completed. If not, continue to adjust until the collected illuminance value reaches the set value. In this way, the feedback of the test target source is realized, making the test process more convenient.

[0077] Further, as a preferred embodiment, step S104 in this embodiment, obtaining the action distance sample based on the test sample and the feature model library based on a preset analysis algorithm, specifically includes:

[0078] According to the test sample, image information of the sample image is obtained;

[0079] Obtaining target features of the sample image according to the image information;

[0080] The target feature is matched with the feature model in the feature model library, and the action distance sample is obtained based on a preset analysis algorithm.

[0081] The image information obtained according to the test sample specifically includes information such as pixel distribution, brightness and color of the sample image.

[0082] After acquiring the image information, it can be converted into digital signals through digital processing, and these signals can be operated by computers to obtain the target features of the sample image. Then these target features can be matched with the feature model to obtain multiple distance samples.

[0083] As a preferred embodiment, the preset analysis algorithm used in this embodiment is specifically an MRC analysis algorithm, that is, a minimum resolvable contrast analysis algorithm. In practice, other existing preset analysis algorithms may also be selected to implement this process.

[0084] In a preferred embodiment, the step S105 of establishing the atmospheric attenuation model includes:

[0085] I=I0*exp(-a*d)

[0086] Where I is the target light intensity, I0 is the initial light intensity, a is the absorption coefficient, and d is the light penetration depth.

[0087] After the atmospheric attenuation model is established, step S106 can be executed, that is, combining the test samples and the effective distance samples, automatically calculating and displaying the ultimate resolution capability of the tested system for low-contrast targets under different illuminations, and the effective distance of the feedback television camera system under different atmospheric visibility, to obtain the required test results.

[0088] The present invention provides a low-contrast action distance test method, which provides test targets with different test backgrounds, different contrasts, and different spatial frequencies by constructing a test target source with adjustable contrast. At the same time, a feature model library is established, and after using the test target source to obtain test samples, the feature model library is combined with the atmospheric attenuation model to obtain the final test results, thereby realizing the function of automatically detecting the resolution ability of the television camera system for low-contrast targets under different illuminations, and accurately evaluating the action distance of the television camera system under different atmospheric visibilities. Compared with the prior art, the present invention is not restricted by the external environment, avoids the influence of errors caused by human subjective judgment, is simple and convenient to operate, has strong versatility, and has high test accuracy, and can effectively measure the action distance of the television camera system for low-contrast targets.

[0089] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0090] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A low contrast range test device, applied to a television camera system, characterized in that: include: A test target source, wherein the contrast of the test target source is continuously adjustable; An image acquisition and processing component, used for acquiring test samples of the test target source at different contrasts in the television camera system to be tested; A test model library building module is used to establish multiple feature models with different contrasts and different spatial resolutions to form a feature model library; An analysis module, used to obtain an action distance sample according to the test sample and the feature model library based on a preset analysis algorithm; The test module is used to establish an atmospheric attenuation model and obtain test results according to the test sample, the action distance sample and the atmospheric attenuation model.

2. The low contrast range test device according to claim 1, characterized in that: The test target source includes two integrating spheres, a positive target, a negative target, a target adjustment bracket and a beam combiner, wherein the positive target and the negative target are respectively arranged at the light output of the two integrating spheres, the patterns on the positive target and the negative target are the same as the background, the patterns of the positive target and the negative target overlap, and the beam combiner is located at the intersection of the light outputs of the two integrating spheres after passing through the positive target and the negative target.

3. The low contrast range test device according to claim 2, characterized in that: It also includes an off-axis reflection device, which includes an off-axis parabolic primary reflector, a plane secondary mirror and a beam splitter prism. The positive target and the negative target are both located at the conjugate focal plane of the off-axis reflection device. The off-axis reflection device is used to collimate the image formed by the test target source into an infinitely distant target.

4. A low contrast working distance testing method, using the low contrast working distance testing device as claimed in any one of claims 1 to 3 and applied to a television camera system, characterized in that: The test method includes: Constructing a test target source, wherein the contrast of the test target source is continuously adjustable; Establish multiple feature models with different contrasts and different spatial resolutions to form a feature model library; Acquire test samples of the test target source at different contrasts in the television camera system to be tested; According to the test sample and the feature model library, based on a preset analysis algorithm, an action distance sample is obtained; Establish atmospheric attenuation model; A test result is obtained according to the test sample, the action distance sample and the atmospheric attenuation model.

5. The low contrast range testing method according to claim 4, characterized in that: The step of establishing a plurality of feature models with different contrasts and different spatial resolutions to form a feature model library includes: Model construction: Establish multiple initial feature models with different contrasts and spatial resolutions; Model sample acquisition: using the television camera system to be measured to acquire multiple model samples of the test target source; Matching test: Match the initial feature model and the model sample. If the match is successful, use the multiple initial feature models as a feature model library. If the match fails, repeat the model construction and the model sample acquisition, and re-perform the matching test.

6. The low contrast range testing method according to claim 4, characterized in that: The test sample includes a sample image collected by a television camera system to be measured, and an illumination value and a contrast value corresponding to the sample image.

7. The low contrast range testing method according to claim 6, characterized in that: The step of obtaining test samples of the test target source at different contrasts in the television camera system to be tested includes: Obtain test samples; The illumination value of the test sample is matched with the preset illumination value. If the match is successful, the test sample is retained. If the match fails, the test target source is adjusted and the test sample is acquired again.

8. The low contrast range testing method according to claim 6, characterized in that: The step of obtaining the action distance sample based on the test sample and the feature model library and a preset analysis algorithm includes: According to the test sample, image information of the sample image is obtained; Obtaining target features of the sample image according to the image information; The target feature is matched with the feature model in the feature model library, and the action distance sample is obtained based on a preset analysis algorithm.

9. The low contrast range testing method according to claim 8, characterized in that: The image information includes pixel distribution, brightness and color of the sample image.

10. The low contrast range testing method according to claim 4, characterized in that: The atmospheric attenuation model includes: I=I0*exp(-a*d) Where I is the target light intensity, I0 is the initial light intensity, a is the absorption coefficient, and d is the light penetration depth.

Images