Transmission testing apparatus, signal-to-noise ratio testing system and testing method

Abstract

This invention provides a transmission testing device, including at least one transmission testing unit. The transmission testing unit includes a first transmission testing subunit, a second transmission testing subunit, and a third transmission testing subunit. The first and second transmission testing subunits are in contact with each other and are both disposed on the third transmission testing subunit. The difference between the optical density of the first and third transmission testing subunits is equal to the difference between the optical density of the third and second transmission testing subunits, and the difference between the optical density of the third and second transmission testing subunits is less than or equal to 0.3. This facilitates obtaining the signal-to-noise ratio (SNR) through contrast and reduces the impact of HDR blending and tone mapping non-monotonicity on the SNR. This invention also provides a signal-to-noise ratio (SNR) testing system and method.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a transmission testing device, a signal-to-noise ratio testing system, and a testing method. Background Technology

[0002] The requirements for the dynamic range of image sensors are constantly increasing, and high dynamic range imaging has become one of the basic requirements for customers. However, due to the physical limitations of the sensors themselves and cost considerations, many manufacturers use High-Dynamic Range (HDR) fusion technology to achieve high dynamic range functionality. HDR fusion technology merges images with different exposures into a single image, while preserving information in both bright and dark areas, achieving better image quality in both day and night. However, in actual testing and operation, the images used for fusion and tone mapping contain different levels of noise, resulting in a non-linear signal-to-noise ratio (SNR) for HDR images at different exposures, and sometimes even abrupt changes. When using traditional methods to test the image SNR, inaccuracies often occur. Furthermore, SNR is not only an important indicator for judging image quality, but it also affects the measurement of other SNR-based indicators, such as dynamic range.

[0003] Therefore, it is necessary to provide a novel transmission testing device, signal-to-noise ratio testing system, and testing method to solve the aforementioned problems existing in the prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a transmission testing device, a signal-to-noise ratio (SNR) testing system, and a testing method, which facilitates obtaining the SNR through contrast and reduces the impact of HDR fusion and non-monotonic tone mapping on the SNR.

[0005] To achieve the above objectives, the transmission testing device of the present invention includes at least one transmission testing unit. The transmission testing unit includes a first transmission testing subunit, a second transmission testing subunit, and a third transmission testing subunit. The first transmission testing subunit and the second transmission testing subunit are in contact with each other and are both disposed on the third transmission testing subunit. In each transmission testing unit, the difference between the optical density of the first transmission testing subunit and the optical density of the third transmission testing subunit is equal to the difference between the optical density of the third transmission testing subunit and the optical density of the second transmission testing subunit, and the difference between the optical density of the third transmission testing subunit and the optical density of the second transmission testing subunit is less than or equal to 0.3.

[0006] The beneficial effects of the transmission testing device are as follows: the transmission testing unit includes a first transmission testing subunit, a second transmission testing subunit, and a third transmission testing subunit. The first transmission testing subunit and the second transmission testing subunit are in contact with each other and are both disposed on the third transmission testing subunit. In each transmission testing unit, the difference between the optical density of the first transmission testing subunit and the optical density of the third transmission testing subunit is equal to the difference between the optical density of the third transmission testing subunit and the optical density of the second transmission testing subunit. Moreover, the difference between the optical density of the third transmission testing subunit and the optical density of the second transmission testing subunit is less than or equal to 0.3, which facilitates obtaining the signal-to-noise ratio through contrast, reduces the impact of HDR fusion and tone mapping non-monotonicity on the signal-to-noise ratio, and obtaining the signal-to-noise ratio based on contrast better reflects the connection between the signal-to-noise ratio and vision.

[0007] Optionally, the first transmission test subunit, the second transmission test subunit, and the third transmission test subunit are all cuboids. The first face of the first transmission test subunit and the first face of the second transmission test subunit together cover part of the first face of the third transmission test subunit. The area of ​​the first face of the first transmission test subunit is equal to the area of ​​the first face of the second transmission test subunit, and the area of ​​the first face of the third transmission test subunit is four times the area of ​​the first face of the first transmission test subunit.

[0008] Optionally, the transmission testing device further includes a background module, and all transmission testing units are disposed on the background module.

[0009] Optionally, the transmission testing device further includes a light-emitting unit, which is disposed on the side of the background module facing away from the transmission testing unit.

[0010] Optionally, the optical density of the third transmission test subunit on different transmission test units increases by m sequentially, where m is greater than 0. This has the advantage of facilitating the calculation of the dynamic range.

[0011] The present invention also provides a signal-to-noise ratio testing system, comprising:

[0012] The transmission testing device;

[0013] Acquisition unit, used for acquiring images from the transmission test unit;

[0014] The acquisition unit is used to acquire the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image.

[0015] The first calculation unit is used to calculate the contrast-based signal-to-noise ratio using the signal-to-noise ratio formula, which is SNR_CR=20×log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean, std represents the standard deviation, and SNR_CR represents the contrast-based signal-to-noise ratio.

[0016] The beneficial effects of the signal-to-noise ratio (SNR) testing system are as follows: the acquisition unit is used to acquire images of the transmission test unit; the acquisition unit is used to acquire the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image; the first calculation unit is used to subtract the first pixel matrix from the second pixel matrix to obtain a two-dimensional matrix; then, the mean and standard deviation of the two-dimensional matrix are calculated; then, the logarithm of the product of the mean and the standard deviation is calculated with base 10; finally, the logarithm is multiplied by a preset threshold to obtain the contrast-based SNR. This facilitates obtaining the SNR through contrast, reduces the impact of HDR fusion and tone mapping non-monotonicity on the SNR, and obtaining the SNR based on contrast better reflects the connection between the SNR and vision.

[0017] Optionally, the signal-to-noise ratio testing system further includes a second calculation unit, which is used to obtain the first optical density of the third transmission test subunit of the transmission test unit with a signal-to-noise ratio of 1, and to obtain the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness.

[0018] Optionally, the signal-to-noise ratio testing system further includes a third calculation unit, which is used to subtract the second optical density from the first optical density and then multiply it by a preset dynamic range threshold to obtain the dynamic range.

[0019] The present invention also provides a signal-to-noise ratio (SNR) testing method for a signal-to-noise ratio (SNR) testing system, comprising the following steps:

[0020] S1: The acquisition unit acquires an image from any one of the transmission test units;

[0021] S2: The acquisition unit acquires the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image;

[0022] S3: The first calculation unit calculates the contrast-based signal-to-noise ratio using the signal-to-noise ratio formula, which is SNR_CR=20×log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean, std represents the standard deviation, and SNR_CR represents the contrast-based signal-to-noise ratio.

[0023] The beneficial effects of the proposed signal-to-noise ratio (SNR) testing method are: it facilitates obtaining the SNR through contrast, reduces the impact of HDR fusion and tone mapping non-monotony on the SNR, and obtaining the SNR based on contrast better reflects the connection between the SNR and vision.

[0024] Optionally, the number of pixels in the region corresponding to the first transmission test subunit in the image and the number of pixels in the region corresponding to the first transmission test subunit in the image are both greater than or equal to 300. The acquisition unit acquires an image of any transmission test unit, including when the acquisition unit is exposed, so that the average gray value of the background of the image is between one-third and two-thirds of the data depth of the acquisition unit. Attached Figure Description

[0025] Figure 1 This is a top view of the transmission test unit in some embodiments of the present invention;

[0026] Figure 2 This is a top view of the transmission testing device in some other embodiments of the present invention;

[0027] Figure 3 This is a top view of the transmission testing device in some embodiments of the present invention;

[0028] Figure 4 This is a structural block diagram of the signal-to-noise ratio testing system in some embodiments of the present invention;

[0029] Figure 5 This is a flowchart of a signal-to-noise ratio testing method in some embodiments of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0031] To address the problems existing in the prior art, embodiments of the present invention provide a transmission testing device, including at least one transmission testing unit.

[0032] Figure 1 This is a top view schematic diagram of the transmission test unit in some embodiments of the present invention. (Refer to...) Figure 1 The transmission testing unit 100 includes a first transmission testing subunit 101, a second transmission testing subunit 102, and a third transmission testing subunit 103. The first transmission testing subunit 101 and the second transmission testing subunit 102 are in contact with each other and are both disposed on the third transmission testing subunit 103. In each transmission testing unit 100, the difference between the optical density of the first transmission testing subunit 101 and the optical density of the third transmission testing subunit 103 is equal to the difference between the optical density of the third transmission testing subunit 103 and the optical density of the second transmission testing subunit 102, and the difference between the optical density of the third transmission testing subunit 103 and the optical density of the second transmission testing subunit 102 is less than or equal to 0.3.

[0033] Reference Figure 1 The first transmission test subunit 101, the second transmission test subunit 102 and the third transmission test subunit 103 are all cuboids.

[0034] Reference Figure 1 The first surface of the first transmission test subunit 101 and the first surface of the second transmission test subunit 102 together cover a portion of the first surface of the third transmission test subunit 103, and the area of ​​the first surface of the first transmission test subunit 101 is equal to the area of ​​the first surface of the second transmission test subunit 102, and the area of ​​the first surface of the third transmission test subunit 103 is four times the area of ​​the first surface of the first transmission test subunit 101.

[0035] Optionally, one edge of the first surface of the first transmission test subunit 101 and one edge of the first surface of the second transmission test subunit 102 completely coincide, and the intersection of the diagonals of the surfaces formed by the first surfaces of the first and second transmission test subunits 101 and the first surfaces of the second transmission test subunit 102 coincides with the intersection of the diagonals of the first surface of the third transmission test subunit 103.

[0036] Figure 2 This is a top view schematic diagram of the transmission testing device in other embodiments of the present invention. (Refer to...) Figure 1 and Figure 2 , Figure 2 and Figure 1 The difference is: Figure 2 Including multiple, such as Figure 1 The transmission test unit 100 shown is connected in sequence. Optionally, the overlapping edges of the first surfaces of the first transmission test subunit 101 and the first surfaces of the second transmission test subunit 102 in two adjacent transmission test units are located on the same straight line.

[0037] Figure 3 This is a top view schematic diagram of the transmission testing device in some embodiments of the present invention. (Refer to...) Figure 2 and reference Figure 3 , Figure 3 and Figure 2 The difference is that the transmission testing device further includes a background module 104, and the transmission testing units 100 are all disposed on the background module 104, and the optical density of the background module 104 is 0.3.

[0038] In some embodiments, the transmission testing apparatus further includes a light-emitting unit disposed on the side of the background module facing away from the transmission testing unit. Optionally, the light-emitting unit is a uniform light source, which includes an integrating sphere or a conventional light source containing a light-diffusing plate.

[0039] Reference Figure 2 and Figure 3 The optical density of the third transmission test subunit 103 on different transmission test units 100 increases by m sequentially, where m is greater than 0. Optionally, the optical density of the third transmission test subunit 103 on different transmission test units 100 increases by 0.3 sequentially.

[0040] Figure 4 This is a structural block diagram of the signal-to-noise ratio testing system in some embodiments of the present invention. (Refer to...) Figure 4The signal-to-noise ratio (SNR) testing system 200 includes the transmission testing device (not shown in the figure), an acquisition unit 201, an acquisition unit 202, and a first calculation unit 203. The acquisition unit 201 is used to acquire images of the transmission testing unit; the acquisition unit 202 is used to acquire the first pixel matrix of the region corresponding to the first transmission testing subunit in the image and the second pixel matrix of the region corresponding to the second transmission testing subunit in the image; the first calculation unit 203 is used to calculate the contrast-based SNR using the SNR formula SNR_CR = 20 × log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean, std represents the standard deviation, and SNR_CR represents the contrast-based SNR. Specifically, the acquisition unit 201 acquires an image of a top view of the transmission testing device.

[0041] In some embodiments, the acquisition unit is a plane-angle lens camera, and the transmission testing device is located 1 meter away from the plane-angle lens camera.

[0042] In some embodiments, the signal-to-noise ratio (SNR) testing system further includes a second calculation unit and a third calculation unit. The second calculation unit is used to obtain the first optical density of the third transmission test subunit of the transmission test unit with a SNR of 1, and to obtain the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness; the third calculation unit is used to subtract the second optical density from the first optical density, and then multiply it by a preset dynamic range threshold to obtain the dynamic range.

[0043] Figure 5 This is a flowchart of a signal-to-noise ratio (SNR) testing method in some embodiments of the present invention. (Refer to...) Figure 5 The signal-to-noise ratio (SNR) test method includes the following steps:

[0044] S1: The acquisition unit acquires an image from any one of the transmission test units;

[0045] S2: The acquisition unit acquires the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image;

[0046] S3: The first calculation unit calculates the contrast-based signal-to-noise ratio using the signal-to-noise ratio formula, which is SNR_CR=20×log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean, std represents the standard deviation, and SNR_CR represents the contrast-based signal-to-noise ratio.

[0047] In some embodiments, the acquisition unit acquires images of the transmission test unit, including acquiring images of the transmission test unit in a single light source environment.

[0048] In some embodiments, the number of pixels in the region corresponding to the first transmission test subunit in the image and the number of pixels in the region corresponding to the first transmission test subunit in the image are both greater than or equal to 300.

[0049] In some embodiments, the acquisition unit acquires an image of any transmission test unit such that the average grayscale value of the background of the image is between one-third and two-thirds of the data depth of the acquisition unit during exposure. Optionally, the average grayscale value of the background of the image is half the data depth of the acquisition unit during exposure. Specifically, when the data depth of the acquisition unit is 8 bits, the average grayscale value of the background of the image is 128; when the data depth of the acquisition unit is 12 bits, the average grayscale value of the background of the image is 2048.

[0050] In some specific embodiments, the background of the image is the image formed by the background module.

[0051] In some embodiments, the signal-to-noise ratio testing method further includes the following steps:

[0052] S4: Repeat steps S1 to S3 to obtain the signal-to-noise ratio of all the transmission test units;

[0053] S5: The second calculation unit obtains the first optical density of the third transmission test subunit of the transmission test unit with a signal-to-noise ratio of 1, and obtains the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness.

[0054] S6: The third calculation unit subtracts the second optical density from the first optical density, and then multiplies it by a preset dynamic range threshold to obtain the dynamic range.

[0055] In some specific embodiments, the preset dynamic range threshold is 20, and the dynamic range is calculated as DR = 20 * (OD(C_SNR_CR = 1) - OD(Clight)), where DR is the dynamic range, OD(C_SNR_CR = 1) is the first optical density of the third transmission test subunit of the transmission test unit with a signal-to-noise ratio of 1, and OD(Clight) is the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness.

[0056] In some embodiments, the second computing unit obtains the first optical density of the third transmission test subunit of the transmission test unit with a signal-to-noise ratio of 1 by adjusting the brightness of the light source if it is determined that the signal-to-noise ratio of all the transmission test units is not 1, until the signal-to-noise ratio of any one of the transmission test units is 1.

[0057] In some embodiments, obtaining the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness includes determining whether the transmission test unit meets the highest brightness condition. If the transmission test unit meets the highest brightness condition, then the transmission test unit is the transmission test unit with the highest brightness. The highest brightness condition is that the area corresponding to the first transmission test subunit in the image is underexposed, the area corresponding to the second transmission test subunit in the image is overexposed, and the area corresponding to the third transmission test subunit in the image is saturated.

[0058] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A signal-to-noise ratio (SNR) testing system, characterized in that, include: A transmission testing device includes a background module, a light-emitting unit, and at least one transmission testing unit. The transmission testing units are all disposed on the background module, and the light-emitting unit is disposed on the side of the background module facing away from the transmission testing unit. Each transmission testing unit includes a first transmission testing subunit, a second transmission testing subunit, and a third transmission testing subunit. The first and second transmission testing subunits are in contact with each other and are both disposed on the third transmission testing subunit. In each transmission testing unit, the difference between the optical density of the first and third transmission testing subunits is equal to the difference between the optical density of the third and second transmission testing subunits, and the difference between the optical density of the third and second transmission testing subunits is less than or equal to 0.

3. The acquisition unit is used to acquire images from the transmission test unit; The acquisition unit is used to acquire the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image. The first calculation unit is used to calculate the contrast-based signal-to-noise ratio using the signal-to-noise ratio formula, which is SNR_CR=20×log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean value, std represents the standard deviation, and SNR_CR represents the contrast-based signal-to-noise ratio.

2. The signal-to-noise ratio testing system according to claim 1, characterized in that, The first transmission test subunit, the second transmission test subunit, and the third transmission test subunit are all cuboids. The first face of the first transmission test subunit and the first face of the second transmission test subunit together cover part of the first face of the third transmission test subunit. The area of ​​the first face of the first transmission test subunit is equal to the area of ​​the first face of the second transmission test subunit, and the area of ​​the first face of the third transmission test subunit is four times the area of ​​the first face of the first transmission test subunit.

3. The signal-to-noise ratio testing system according to claim 1, characterized in that, The optical density of the third transmission test subunit on different transmission test units increases by m sequentially, where m is greater than 0.

4. The signal-to-noise ratio testing system according to claim 1, characterized in that, It also includes a second calculation unit, which is used to obtain the first optical density of the third transmission test subunit of the transmission test unit with a signal-to-noise ratio of 1, and to obtain the second optical density of the third transmission test subunit of the transmission test unit with the highest brightness.

5. The signal-to-noise ratio testing system according to claim 4, characterized in that, It also includes a third calculation unit, which is used to subtract the second optical density from the first optical density and then multiply it by a preset dynamic range threshold to obtain the dynamic range.

6. A signal-to-noise ratio (SNR) testing method for the SNR testing system according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: The acquisition unit acquires an image from any one of the transmission test units; S2: The acquisition unit acquires the first pixel matrix of the region corresponding to the first transmission test subunit in the image and the second pixel matrix of the region corresponding to the second transmission test subunit in the image; S3: The first calculation unit calculates the contrast-based signal-to-noise ratio using the signal-to-noise ratio formula, which is SNR_CR=20×log(mean(DN_A-DN_B) / std(DN_A-DN_B)), where DN_A represents the first pixel matrix, DN_B represents the second pixel matrix, mean represents the mean, std represents the standard deviation, and SNR_CR represents the contrast-based signal-to-noise ratio.

7. The signal-to-noise ratio testing method according to claim 6, characterized in that, The number of pixels in the region corresponding to the first transmission test subunit in the image and the number of pixels in the region corresponding to the first transmission test subunit in the image are both greater than or equal to 300. The acquisition unit acquires an image of any transmission test unit, including when the acquisition unit is exposed, so that the average gray value of the background of the image is between one-third and two-thirds of the data depth of the acquisition unit.

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