OCTA image processing method and system based on intensity-phase fusion

Abstract

The present invention belongs to the field of image processing technology. Provided is an OCTA image processing method and system based on intensity phase fusion, which performs split spectrum processing on OCTA data to obtain multiple sub-band signals; for any sub-band signal, based on the inter-frame error between the current frame OCTA image and the previous frame OCTA image, performs time domain phase correction and frequency domain phase correction on each frame OCTA image; based on the results of the frequency domain correction, determines the intensity difference image and phase difference image between the current frame OCTA image and the previous frame OCTA image, and then obtains an intensity phase fusion image of the current frame OCTA image; superimposes the intensity phase fusion images corresponding to each frame OCTA image of each sub-band signal to obtain a fused OCTA image. The present invention can avoid jump errors in moving areas without sacrificing the phase resolution of static areas, thereby improving the accuracy of OCTA image correction.

Description

Technical Field

[0001] The present invention relates to the technical field of image processing, and in particular to an OCTA image processing method and system based on intensity-phase fusion. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Optical coherence tomography angiography (OCTA) is a non-invasive imaging technology that can detect tiny blood flow movements in tissues by scanning the same location multiple times. Typical OCTA algorithms use intensity differences or phase changes in consecutive B-scan frames to extract vascular networks.

[0004] However, in actual acquisition, large scanning motion can cause erroneous intensity decorrelation or phase jumps in stationary tissue, reducing contrast and blurring details. Even subtle motion in the subject or sample can cause displacement errors in adjacent frames, leading to false flow signals and image artifacts. Traditional methods typically use fixed motion correction and filtering strategies, applying a uniform low-pass filter to suppress noise throughout the entire process or assuming system phase stability without adequate correction. This one-size-fits-all approach is difficult to adapt to varying degrees of motion. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention provides an OCTA image processing method and system based on intensity-phase fusion. Through an inter-frame displacement feedback control mechanism, "adaptive smoothing" of phase unwrapping (i.e., restoring the continuous phase from the wrapped phase) is achieved. Compared with the fixed parameter method, adaptive control can avoid jump errors in moving areas without sacrificing phase resolution in static areas, greatly improving the accuracy of OCTA image correction.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An OCTA image processing method based on intensity phase fusion includes the following steps:

[0008] Acquire OCTA data obtained by repeated scanning at the current position, perform spectrum splitting processing on the OCTA data to obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0009] For any sub-band signal, time-domain phase correction is performed on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is then performed on the result of the time-domain phase correction based on the inter-frame error. The intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame are determined based on the frequency-domain correction result, thereby obtaining the intensity-phase fusion image of the current OCTA image frame.

[0010] The intensity-phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed to obtain a fused OCTA image of the current position.

[0011] In a second aspect, the present invention provides an OCTA image processing system based on intensity-phase fusion.

[0012] An OCTA image processing system based on intensity-phase fusion, comprising:

[0013] a spectral splitting processing unit configured to: acquire OCTA data obtained by repeated scanning at a current position, perform spectral splitting processing on the OCTA data, and obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0014] The intensity-phase fusion unit is configured to: perform time-domain phase correction on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame for any sub-band signal; perform frequency-domain phase correction on the result of the time-domain phase correction based on the inter-frame error; determine the intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame based on the result of the frequency-domain correction, and thereby obtain an intensity-phase fusion image of the current OCTA image frame;

[0015] The superposition processing unit is configured to superimpose the intensity-phase fused images corresponding to each frame of the OCTA image of each sub-band signal to obtain a fused OCTA image of the current position.

[0016] In a third aspect, the present invention provides a computer device comprising: a processor and a computer-readable storage medium;

[0017] a processor adapted to execute a computer program;

[0018] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the OCTA image processing method based on intensity phase fusion according to the first aspect of the present invention is implemented.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is suitable for being loaded by a processor and executing the OCTA image processing method based on intensity phase fusion as described in the first aspect of the present invention.

[0020] In a fifth aspect, the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the OCTA image processing method based on intensity phase fusion as described in the first aspect of the present invention.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention performs time-domain phase correction on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is then performed on the results of the time-domain phase correction based on the inter-frame error. Through an inter-frame displacement feedback control mechanism, "adaptive smoothing" of phase unwrapping is achieved. Compared with fixed parameter methods, adaptive control can avoid jump errors in moving areas without sacrificing phase resolution in static areas.

[0023] 2. The present invention determines the intensity difference image and phase difference image between the current OCTA frame image and the previous OCTA frame image based on the results of frequency domain correction, and then obtains the intensity-phase fusion image of the current OCTA frame image. The intensity-phase fusion images corresponding to each frame of OCTA image of each sub-band signal are superimposed to obtain the fused OCTA image of the current position. This phase-intensity composite expression can fuse intensity change information while retaining phase sensitivity, taking into account flow velocity sensitivity and signal-to-noise ratio. Compared with pure phase or pure intensity difference methods, the present invention is more suitable for detecting low-flow capillaries, identifying capillary rupture areas, and enhancing weak-signal vascular structures.

[0024] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 A schematic flow chart of an OCTA image processing method based on intensity phase fusion provided by an exemplary embodiment of the present invention;

[0027] Figure 2A schematic diagram illustrating the principle of an OCTA image processing method based on intensity phase fusion provided by an exemplary embodiment of the present invention;

[0028] Figure 3 A schematic diagram of an OCTA image processing system based on intensity phase fusion provided by an exemplary embodiment of the present invention;

[0029] Figure 4 A schematic diagram of a computer device is provided for an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0032] This implementation proposes an OCTA image processing method based on intensity phase fusion, such as Figure 1 and Figure 2 As shown, the following process is included:

[0033] S101: Acquire OCTA data obtained by repeated scanning at the current position (i.e. Figure 2 ), performing spectrum splitting processing on the OCTA data to obtain multiple sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0034] S102: For any sub-band signal, perform time domain phase correction on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame, perform frequency domain phase correction on the result of the time domain phase correction based on the inter-frame error, determine an intensity difference image and a phase difference image between the current OCTA image frame and the previous OCTA image frame based on the result of the frequency domain correction, and thereby obtain an intensity-phase fused image of the current OCTA image frame;

[0035] S103: Superimposing the intensity-phase fused images corresponding to each frame of the OCTA image of each sub-band signal to obtain a fused OCTA image of the current position.

[0036] In S101 of this implementation, specifically, the following steps are included:

[0037] Under the split spectrum strategy, let the original complex signal be , decompose the signal into L sub-band signals:

[0038] (1);

[0039] in, For the The window function corresponding to each subband (such as Gaussian window or rectangular window), is the wave number, represents the axial coordinate in the time domain, represents the horizontal coordinate in the time domain, Represents time.

[0040] In S102 of this implementation, specifically, the following steps are included:

[0041] Perform time domain phase correction on each subband signal separately:

[0042] First perform axial phase correction:

[0043] (2);

[0044] Then perform lateral phase correction:

[0045] (3);

[0046] in, Indicates the phase is unwrapped, X and Y are the maximum values ​​of the time domain coordinates, Representative The first subband signal The conjugate signal of the original signal of the OCTA image frame.

[0047] Integrated time domain phase difference for:

[0048] (4);

[0049] Due to the existence of motion, it is necessary to perform windowing and smoothing on the phase after unwrapping. The present invention performs phase processing adaptively according to the magnitude of the motion, and Set the unwrapping sliding average window width When the displacement is large, a wider smoothing kernel is used to ensure phase continuity, and when the displacement is small, a narrower window is used to avoid over-smoothing, achieving a dynamic balance between unwrapping accuracy and stability:

[0050] (5);

[0051] in, Represents the upper limit of the unwrapping window length, Represents the lower limit of the unwrapping window length, Represents the lower limit of motion displacement threshold, represents the upper limit of the motion displacement threshold, is the slope factor.

[0052] Then, the phase is processed according to the motion amplitude

[0053] (6);

[0054] Wherein, 2W(M)+1 is the total window length, which is used to ensure central symmetry.

[0055] Then, the signal after correction is:

[0056] (7).

[0057] Here, i is the imaginary unit.

[0058] For the calculation of the displacement amplitude M, the present invention provides the following method:

[0059] Two adjacent frames of image and Perform Fast Fourier Transform (FFT) to obtain the respective spectrum representations and , and then calculate their normalized cross-power spectrum:

[0060] (8);

[0061] in, represents the complex conjugate, and is the frequency domain coordinate.

[0062] Then perform inverse FFT on R(u,v) to get the correlation function r(x,y). The position of the correlation peak is the plane displacement between frames. , the estimated plane displacement For the second frame Perform registration correction based on the Fourier translation property. Apply linear phase factor , where U and V are the maximum values ​​of the frequency domain coordinates, corresponding to the image size, which is equivalent to translating the image in the spatial domain To align the first frame, the image after compensation of translation can be obtained by inverse FFT , this step outputs and records a motion amplitude M for subsequent adaptive processing:

[0063] (9).

[0064] Convert an image from the time domain to the frequency domain:

[0065] (10);

[0066] Correct the phase in the frequency domain:

[0067] (11);

[0068] (12);

[0069] Comprehensive frequency domain phase difference:

[0070] (13);

[0071] Similarly, phase processing is performed adaptively according to the magnitude of the motion:

[0072] (14);

[0073] (15);

[0074] After processing, the corrected frequency domain subband signal is inverse Fourier transformed to obtain the final subband signal:

[0075] (16);

[0076] It should be noted that .

[0077] Then calculate the intensity difference image and phase difference image. The intensity difference image is:

[0078] (17);

[0079] The phase difference image is:

[0080] (18);

[0081] (19);

[0082] (20);

[0083] The intensity-phase fusion image is:

[0084] (twenty one);

[0085] In S103 of this implementation, specifically, all sub-band signals are superimposed as the final processed position OCTA images, including:

[0086] (twenty two).

[0087] The above describes in detail the OCTA image processing method based on intensity phase fusion of the present invention. In order to better implement the above method of the present invention, the following provides an OCTA image processing method based on intensity phase fusion, such as Figure 3 Shown, including:

[0088] The spectrum splitting processing unit 301 is configured to: obtain OCTA data obtained by repeated scanning at a current position, perform spectrum splitting processing on the OCTA data, and obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0089] The intensity-phase fusion unit 302 is configured to: perform time-domain phase correction on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame for any sub-band signal; perform frequency-domain phase correction on the result of the time-domain phase correction based on the inter-frame error; determine an intensity difference image and a phase difference image between the current OCTA image frame and the previous OCTA image frame based on the result of the frequency-domain correction, and thereby obtain an intensity-phase fused image of the current OCTA image frame;

[0090] The superposition processing unit 303 is configured to superimpose the intensity-phase fused images corresponding to each frame of the OCTA image of each sub-band signal to obtain a fused OCTA image of the current position.

[0091] It is understandable that each of the above-mentioned units can be separately or completely combined into one or several other units to form a unit, or one (or some) of the units can be further divided into multiple functionally smaller units to form a unit, which can achieve the same operation without affecting the realization of the technical effects of the embodiments of the present application. The above-mentioned units are divided based on logical functions. In actual applications, the functions of one unit can also be implemented by multiple units, or the functions of multiple units can be implemented by one unit. In other embodiments of the present application, the system may also include other units. In actual applications, these functions can also be implemented with the assistance of other units and can be implemented by the collaboration of multiple units.

[0092] According to another embodiment of the present application, the system described in this embodiment can be constructed by running a computer program (including program code) capable of executing the steps involved in the corresponding method described in Example 1 on a general-purpose computing device such as a computer, which includes processing elements and storage elements such as a central processing unit (CPU), random access memory (RAM), and read-only memory (ROM). The computer program can be recorded on, for example, a computer-readable recording medium, and loaded into the above-mentioned computing device through the computer-readable recording medium and run therein.

[0093] Figure 4 A computer device is shown, which includes a processor 401, a communication interface 402, and a computer-readable storage medium 403. The processor 401, the communication interface 402, and the computer-readable storage medium 403 may be connected via a bus or other means.

[0094] Among them, the communication interface 402 is used to receive and send data, the computer-readable storage medium 403 can be stored in the memory of the electronic device, the computer-readable storage medium 403 is used to store computer programs, the computer programs include program instructions, and the processor 401 is used to execute the program instructions stored in the computer-readable storage medium 403.

[0095] The processor 401 is the computing core and control core of the electronic device, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions to implement corresponding method processes or corresponding functions.

[0096] The processor 401 is configured to perform the following process:

[0097] Acquire OCTA data obtained by repeated scanning at the current position, perform spectrum splitting processing on the OCTA data to obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0098] For any sub-band signal, time-domain phase correction is performed on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is performed on the result of the time-domain phase correction based on the inter-frame error. The intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame are determined based on the result of the frequency-domain correction, thereby obtaining an intensity-phase fused image of the current OCTA image frame.

[0099] The intensity-phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed to obtain a fused OCTA image of the current position.

[0100] The present invention also provides a computer-readable storage medium, which is a memory device in an electronic device for storing programs and data. It is understood that the computer-readable storage medium herein may include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The computer-readable storage medium provides storage space that stores the processing system of the electronic device.

[0101] Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by the processor. These instructions may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium herein may be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device; alternatively, it may be at least one computer-readable storage medium located remotely from the processor.

[0102] In one embodiment, the computer-readable storage medium stores one or more instructions; the processor loads and executes the one or more instructions stored in the computer-readable storage medium to implement the following process:

[0103] Acquire OCTA data obtained by repeated scanning at the current position, perform spectrum splitting processing on the OCTA data to obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0104] For any sub-band signal, time-domain phase correction is performed on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is performed on the result of the time-domain phase correction based on the inter-frame error. The intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame are determined based on the result of the frequency-domain correction, thereby obtaining an intensity-phase fused image of the current OCTA image frame.

[0105] The intensity-phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed to obtain a fused OCTA image of the current position.

[0106] The present invention also provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the following process:

[0107] Acquire OCTA data obtained by repeated scanning at the current position, perform spectrum splitting processing on the OCTA data to obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images;

[0108] For any sub-band signal, time-domain phase correction is performed on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is performed on the result of the time-domain phase correction based on the inter-frame error. The intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame are determined based on the result of the frequency-domain correction, thereby obtaining an intensity-phase fused image of the current OCTA image frame.

[0109] The intensity-phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed to obtain a fused OCTA image of the current position.

[0110] Those skilled in the art will appreciate that the units and algorithmic steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0111] The above embodiments can be implemented in whole or in part using software, hardware, firmware, or any combination thereof. When implemented using software, they can be implemented in whole or in part in the form of a computer program product. A computer program product comprises one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted via a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer, or a data processing device such as a server or data center that integrates one or more available media. Available media can include magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives).

[0112] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An OCTA image processing method based on intensity-phase fusion, characterized in that: The following processes are included: Acquire OCTA data obtained by repeated scanning at the current position, perform spectrum splitting processing on the OCTA data to obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images; For any sub-band signal, time-domain phase correction is performed on each OCTA image frame based on the inter-frame error between the current OCTA image frame and the previous OCTA image frame. Frequency-domain phase correction is performed on the result of the time-domain phase correction based on the inter-frame error. The intensity difference image and phase difference image between the current OCTA image frame and the previous OCTA image frame are determined based on the result of the frequency-domain correction, thereby obtaining an intensity-phase fused image of the current OCTA image frame. The intensity-phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed to obtain a fused OCTA image of the current position.

2. The OCTA image processing method based on intensity phase fusion according to claim 1, characterized in that: Based on the inter-frame error between the current OCTA image and the previous OCTA image, time domain phase correction is performed on each OCTA image frame, including: ； in, Representative The first subband signal The time domain phase correction results of the frame OCTA image, Representative The first subband signal The original signal of the OCTA image frame, Represents the result of time domain phase processing based on inter-frame error, represents the axial coordinate in the time domain, Represents the horizontal coordinate in the time domain.

3. The OCTA image processing method based on intensity phase fusion according to claim 2, characterized in that: ； in, = + , is the axial phase correction result in the time domain, is the result of lateral phase correction in the time domain, represents the width of the unwrapping sliding average window, and M represents the motion amplitude calculated based on the inter-frame error; ； in, Represents the upper limit of the unwrapping window length, Represents the lower limit of the unwrapping window length, Represents the lower limit of motion displacement threshold, represents the upper limit of the motion displacement threshold, is the slope factor.

4. The OCTA image processing method based on intensity phase fusion according to claim 2, characterized in that: Performing frequency domain phase correction on a result of the time domain phase correction according to the inter-frame error, including: ； in, For the general The result of conversion to frequency domain is, Represents the result of frequency domain phase processing based on inter-frame error, and Represents the coordinates in the frequency domain.

5. The OCTA image processing method based on intensity phase fusion according to claim 4, characterized in that: ； in, b(u,v)= + , is the axial phase correction result in the frequency domain, is the result of lateral phase correction in the frequency domain, represents the unwrapping sliding average window width, and M represents the motion amplitude calculated based on the inter-frame error.

6. The OCTA image processing method based on intensity phase fusion according to claim 4, characterized in that: The intensity difference image and phase difference image between the current OCTA image and the previous OCTA image are determined based on the results of the frequency domain correction, thereby obtaining an intensity-phase fusion image of the current OCTA image, including: right Perform inverse Fourier transform to obtain The final sub-band signal of the frame OCTA image : ; Intensity difference image for: ,in, For the The final sub-band signal of the frame OCTA image; Phase contrast image for: ； ； ； The intensity-phase fusion image is: ； The intensity phase fusion images corresponding to each frame of OCTA images of each sub-band signal are superimposed, including: ； Where T represents the total number of sub-band signals, Represents the current position, Representative The first subband signal The conjugate signal of the original signal of the OCTA image frame.

7. An OCTA image processing system based on intensity-phase fusion, characterized in that: include: a spectral splitting processing unit configured to: acquire OCTA data obtained by repeated scanning at a current position, perform spectral splitting processing on the OCTA data, and obtain a plurality of sub-band signals, wherein each sub-band signal includes the same number of OCTA images; an intensity-phase fusion unit configured to: perform time-domain phase correction on each OCTA image frame according to an inter-frame error between a current OCTA image frame and a previous OCTA image frame for any sub-band signal, perform frequency-domain phase correction on the result of the time-domain phase correction according to the inter-frame error, determine an intensity difference image and a phase difference image between the current OCTA image frame and the previous OCTA image frame according to the result of the frequency-domain correction, and thereby obtain an intensity-phase fusion image of the current OCTA image frame; The superposition processing unit is configured to superimpose the intensity-phase fused images corresponding to each frame of the OCTA image of each sub-band signal to obtain a fused OCTA image of the current position.

8. A computer device, characterized in that: include: a processor and a computer-readable storage medium; a processor adapted to execute a computer program; A computer-readable storage medium having a computer program stored therein, wherein when the computer program is executed by the processor, the OCTA image processing method based on intensity phase fusion according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor and executing the OCTA image processing method based on intensity phase fusion according to any one of claims 1 to 6.

10. A computer program product, characterized in that The computer program product includes a computer program, and when the computer program is executed by a processor, the OCTA image processing method based on intensity phase fusion according to any one of claims 1 to 6 is implemented.

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