Quantitative calculation and evaluation methods for image motion compensation effect

Abstract

The present invention relates to the cross-technical field of aviation optical imaging and motion control, and in particular to a quantitative calculation method and evaluation method for image motion compensation effect, comprising the following steps: S1. acquiring an image representation of a target picture without image motion, and calculating the modulation contrast of the target picture without image motion; S2. introducing a motion function, and acquiring an image representation of an image motion target picture coupled with the motion function; S3. calculating the modulation contrast of the image motion target picture after the image motion is generated within the integration time of an imaging system according to the optical imaging principle; and S4. calculating an image motion quantitative evaluation transfer function, wherein the index is a number with a value of 0-1, and the image motion compensation capability that can be achieved within the integration time of the system can be represented by the ratio of two modulation contrasts. Due to the normalization effect, the index can also be used to compare the capabilities of different image motion compensation systems horizontally.

Description

Technical Field

[0001] The invention belongs to the cross-technical field of aviation optical imaging and motion control, and in particular relates to a quantitative calculation method and evaluation index of image motion compensation effect. Background Art

[0002] In aerial optoelectronic imaging systems, image motion is an image deviation phenomenon caused by various factors such as platform motion, attitude change, and environmental interference. Image motion not only causes image blur and distortion, seriously affecting image clarity and resolution, but also has a negative impact on subsequent image processing and information extraction. Therefore, how to effectively quantify and compensate for image motion has become one of the key technologies to improve the overall performance of aerial optoelectronic imaging systems.

[0003] The traditional solution is to directly evaluate the image degradation before and after the image motion is introduced based on intuitive observation. This method can only meet the needs of preliminary image motion compensation evaluation. It cannot reflect the specific image motion compensation effect of the system, and it is even more impossible to quantitatively compare the image motion conditions and image motion compensation capabilities between different imaging systems.

[0004] At present, although a variety of image motion compensation technologies have been proposed and applied, most of them rely on subjective judgment or simple image quality indicators when evaluating the compensation effect, and lack a unified, quantitative evaluation standard and quantitative calculation method that is directly coupled with the motion function. This not only limits the optimization of the compensation algorithm, but also cannot ensure the consistency and reliability of the compensation effect in different application scenarios. Therefore, a method for quantitatively calculating and evaluating the size of image motion is urgently needed to optimize the image motion compensation technology more scientifically and effectively, and further improve the application effect of optoelectronic imaging systems in complex environments. Summary of the invention

[0005] In view of this, the existing image motion compensation effect lacks objective quantitative evaluation criteria and calculation methods, and cannot directly reflect the degradation of image quality after the imaging effect is coupled with the motion function. The present invention aims to provide a quantitative calculation method and evaluation index for the image motion compensation effect.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] A quantitative calculation method for image motion compensation effect, the quantitative calculation method for image motion compensation effect comprising the steps of:

[0008] S1. Obtain an image representation of a target image without image motion, and calculate the modulation contrast of the target image without image motion ; The non-image-shift target image is not affected by image shift or has been compensated for image shift;

[0009] S2. Introducing a motion function to obtain an image representation of an image of a target image coupled to the motion function;

[0010] S3. According to the principle of optical imaging, calculate the modulation contrast of the image of the target after the image shift occurs within the integration time of the imaging system. ;

[0011] S4. Calculation of image shift quantitative evaluation transfer function ;

[0012] ;

[0013] The transfer function is quantitatively evaluated by the image shift A quantitative calculation of the image motion compensation effect is achieved.

[0014] Furthermore, the image representation of the target image without image shift is:

[0015] ;

[0016] in, , is a constant, is the spatial frequency; is a motion function of the spatial coordinate x, which is a constant when it is not affected by image motion or has been compensated for image motion. ;

[0017] The non-image shift target image modulation contrast for:

[0018] .

[0019] Furthermore, after the motion function is introduced, we have:

[0020] ;

[0021] in, is the movement speed, For exercise time;

[0022] The image representation of the image of the image shift target coupled with the motion function is obtained as follows:

[0023] .

[0024] Furthermore, according to the optical imaging principle, the image of the moving target image generated during the integration time of the imaging system is represented as:

[0025] ;

[0026] in, represents the integration time of the imaging system;

[0027] The image motion target image that moves during the integration time of the imaging system will produce an image motion effect, and then calculate the modulation contrast of the image motion target image after the image motion effect is produced. for:

[0028] .

[0029] Further, the power spectrum is extracted according to the target image without image motion, and the modulation contrast of the target image without image motion is calculated. for:

[0030] ;

[0031] in, represents the intensity contrast, Indicates the maximum intensity, Indicates the minimum intensity.

[0032] Furthermore, the power spectrum is extracted from the image of the image shift target, and the modulation contrast of the image of the image shift target after the image shift occurs within the integration time of the imaging system is calculated. for:

[0033] ;

[0034] in, represents the image intensity contrast of the image shift, represents the maximum image intensity of the image shift, Indicates the minimum image intensity of the image shift.

[0035] Furthermore, the image shift quantitative evaluation transfer function for:

[0036]

[0037] The present invention also provides an evaluation index for image motion compensation effect, wherein the evaluation index for image motion compensation effect is an image motion quantitative evaluation transfer function ; The image shift quantitative evaluation transfer function It is calculated by the quantitative calculation method of the image motion compensation effect mentioned above.

[0038] Compared with the prior art, the invention can achieve the following beneficial effects:

[0039] The present invention proposes a quantitative calculation method for image motion compensation effect, and obtains an evaluation index of image motion compensation effect through the quantitative calculation method as image motion quantitative evaluation transfer function , this index is a number with a value of 0-1, where the denominator is the contrast function of the power spectrum obtained from the original image or the image after image motion compensation, and the numerator is the power spectrum contrast function obtained from the image motion image after the image motion is affected. The ratio of the two can represent the image motion compensation capability that can be achieved within the integration time of the system. Due to the normalization effect, this index can also be used to compare the capabilities of different image motion compensation systems horizontally. Therefore, this index can be used as an evaluation index and quantitative calculation method for image motion compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0041] Figure 1 A schematic flow chart of a quantitative calculation method for image motion compensation effect according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of an image of a target image without image shift according to an embodiment of the present invention;

[0043] Figure 3 A schematic diagram of an image power spectrum of a target image without image shift according to an embodiment of the present invention;

[0044] Figure 4 A schematic diagram of the image power spectrum of the image shift target picture described in the embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0046] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0048] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0049] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0050] like Figure 1 As shown, a flow chart of a quantitative calculation method of an image motion compensation effect according to an embodiment of the present invention is shown. It can be seen from the figure that an embodiment of the present invention provides a quantitative calculation method of an image motion compensation effect, and the quantitative calculation method of an image motion compensation effect comprises the steps of:

[0051] S1. Figure 2 As shown, it is a schematic diagram of an image of a target image without image motion according to an embodiment of the present invention. Such a pattern is usually used in experiments related to image motion compensation. The first step is to obtain an image representation of the target image without image motion, and calculate the modulation contrast of the target image without image motion. ; Wherein, the non-image motion target image is not affected by the image motion or has been compensated for the image motion; Specifically, the image motion is quantitatively calculated using equally spaced black and white stripes as targets, and the image representation of the non-image motion target image is as shown in formula (1):

[0052] (1);

[0053] in, , is a constant, is the spatial frequency; is a motion function of the spatial coordinate x, which is a constant when it is not affected by image motion or has been compensated for image motion. ;

[0054] Then, the modulation contrast of the target image without image motion, which is not affected by image motion or after image motion compensation, is calculated by the curve on the image plane. It is expressed as formula (2):

[0055] (2).

[0056] In a specific embodiment, Figure 3 As shown in FIG. 1 , it is a schematic diagram of the image power spectrum of the non-image shift target image according to the embodiment of the present invention. It can be seen from the figure that the intensity contrast of the power spectrum curve can be approximately equal to its modulation contrast. , that is, the image of the target image without image shift is obtained to extract the power spectrum curve, and then use formula (3):

[0057] (3);

[0058] represents the intensity contrast, Indicates the maximum intensity, Indicates the minimum intensity.

[0059] The modulation contrast of the target image without image motion can be quickly calculated .

[0060] S2. Introduce a motion function to obtain an image representation of the image of the target image with image shift coupled with the motion function; specifically, introduce a motion function to represent the coupling effect of image shift on the image of the target image without image shift. Image shift is essentially a phenomenon in which the image point is coupled with the motion function during the integration time, thereby generating blur. When the motion function is introduced, It is expressed as formula (4):

[0061] (4);

[0062] in, is the movement speed, is the motion time; then the image of the image of the target coupled with the motion function is expressed as formula (5):

[0063] (5)

[0064] The image of the new image-shifted target picture after the motion function is introduced has the same shape as the image of the original image-shifted target picture, but has a phase advance determined by the motion vector.

[0065] S3. According to the principle of optical imaging, calculate the modulation contrast of the image of the target after the image shift occurs within the integration time of the imaging system. Specifically, according to the principle of optical imaging, the intensity of any image point is proportional to the average intensity within the integration time interval. The image of the moving target image generated during the integration time of the imaging system is expressed as shown in formula (6):

[0066] (6);

[0067] in, represents the integration time of the imaging system;

[0068] The image motion target image that moves during the integration time of the imaging system will produce an image motion effect, and then calculate the modulation contrast of the image motion target image after the image motion effect is produced. As shown in formula (7):

[0069] (7).

[0070] in, is the spatial frequency, when When the value becomes zero, this is the image blur Equal to spatial frequency The reciprocal point of The spatial frequency is similar to that in the spatial domain less than Since these blur radii are smaller than the actual minimum blur radius, they are greater than These high spatial frequencies are "false resolution".

[0071] Similar to S1, Figure 4 As shown in the figure, it is a schematic diagram of the image power spectrum of the image shift target picture according to the embodiment of the invention. It can be seen from the figure that the power spectrum can be extracted according to the image of the image shift target picture, and the modulation contrast of the image shift target picture after the image shift effect is generated within the integration time of the imaging system can be calculated. As shown in formula (8):

[0072] (8);

[0073] in, represents the image intensity contrast of the image shift, represents the maximum image intensity of the image shift, Indicates the minimum image intensity of the image shift.

[0074] The modulation contrast of the image of the moving target can be quickly calculated .

[0075] S4. Calculation of image shift quantitative evaluation transfer function Specifically, by comparing the contrast of the target image with image shift and the contrast of the original target image without image shift, the image shift quantitative evaluation transfer function can be quickly obtained to quantitatively measure the image shift. As shown in formula (9):

[0076] (9);

[0077] In the case of extracting the power spectrum similar to S1 and S3, the image shift quantitative evaluation transfer function can be quickly obtained: As shown in formula (10):

[0078] (10).

[0079] The transfer function is quantitatively evaluated by the image shift A quantitative calculation of the image motion compensation effect is achieved.

[0080] An evaluation index of image motion compensation effect provided by an embodiment of the present invention is an image motion quantitative evaluation transfer function , this index is a number with a value of 0-1, where the denominator is the contrast function of the power spectrum obtained from the original image or the image after image motion compensation, and the numerator is the power spectrum contrast function obtained from the image motion image after the image motion is affected. The ratio of the two can represent the image motion compensation capability that can be achieved within the integration time of the system. Due to the normalization effect, this index can also be used to compare the capabilities of different image motion compensation systems horizontally. Therefore, this index can be used as an evaluation index and quantitative calculation method for image motion compensation.

[0081] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0082] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A quantitative calculation method for image motion compensation effect, characterized in that: The quantitative calculation method of the image motion compensation effect comprises the steps of: S1. Obtain an image representation of a target image without image motion, and calculate the modulation contrast of the target image without image motion ; The non-image-shift target image is not affected by image shift or has been compensated for image shift; S2. Introducing a motion function to obtain an image representation of an image of a target image coupled to the motion function; S3. According to the principle of optical imaging, calculate the modulation contrast of the image of the target after the image shift occurs within the integration time of the imaging system. ; S4. Calculation of image shift quantitative evaluation transfer function ; ； The transfer function is quantitatively evaluated by the image shift A quantitative calculation of the image motion compensation effect is achieved.

2. The quantitative calculation method of image motion compensation effect according to claim 1, characterized in that: The image representation of the non-image-shift target picture is: ； in, , is a constant, is the spatial frequency; is a motion function of the spatial coordinate x, which is a constant when it is not affected by image motion or has been compensated for image motion. ; The non-image-shift target image modulation contrast for: 。 3. The quantitative calculation method of image motion compensation effect according to claim 2, characterized in that: After the motion function is introduced, then: ； in, is the movement speed, For exercise time; The image representation of the image of the image shift target coupled with the motion function is obtained as follows: 。 4. The quantitative calculation method of image motion compensation effect according to claim 3, characterized in that: According to the principle of optical imaging, the image of the moving target image produced during the integration time of the imaging system is represented as: ； in, represents the integration time of the imaging system; The image motion target image that moves during the integration time of the imaging system will produce an image motion effect, and then calculate the modulation contrast of the image motion target image after the image motion effect is produced. for: 。 5. The quantitative calculation method of image motion compensation effect according to claim 1, characterized in that: Extract the power spectrum from the non-image motion target image and calculate the modulation contrast of the non-image motion target image for: ； in, represents the intensity contrast, Indicates the maximum intensity, Indicates the minimum intensity.

6. The quantitative calculation method of image motion compensation effect according to claim 5, characterized in that: Extract the power spectrum from the image of the image shift target and calculate the modulation contrast of the image of the image shift target after the image shift occurs within the integration time of the imaging system. for: ； in, represents the image intensity contrast of the image shift, represents the maximum image intensity of the image shift, Indicates the minimum image intensity of the image shift.

7. The quantitative calculation method of image motion compensation effect according to claim 6, characterized in that: The image shift quantitative evaluation transfer function for: 。 8. A method for evaluating image motion compensation effect, characterized in that: Quantitative evaluation of transfer function using image shift As the evaluation index of the image motion compensation effect; the image motion quantitative evaluation transfer function The image motion compensation effect is calculated by the quantitative calculation method according to any one of claims 1 to 7.

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