Optical coherence tomography image saturation artifact suppression method and system

Abstract

The invention relates to the field of optics, in particular to an optical coherence tomography image saturation artifact suppression method and system. The method comprises the following steps: laser emitted by a light source is split by a light splitting element and then enters an annular reflector at a preset angle; a light through hole with a preset size is formed in the center of the mirror surface of the reflector, and the central part of an incident light beam directly penetrates through the light through hole to enter a reference arm light path; the annular part of the light beam is reflected by the mirror surface, enters the lens through the scanning system and is finally focused on a sample; backscattering light returned from the sample returns along an original light path and enters the detector through the light splitting element. Through the synergistic effect of optical path optimization and adaptive image fusion, the problem of saturation artifacts in a high dynamic range scene is systematically solved. According to the method, the saturation artifacts are effectively eliminated, meanwhile, the edge structure information of the low-reflection area is completely reserved, and the imaging quality and the measurement precision of the image are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of optics, and more specifically, to a method and system for suppressing saturation artifacts in optical coherence tomography images. Background Technology

[0002] Optical coherence tomography (OCT), as a representative of non-contact point scanning high-resolution optical imaging technology, is widely used in biomedical diagnostics and industrial non-destructive testing. However, when the sample under test has a local strong reflective interface within the scanning field of view, the received signal can easily exceed the linear response range of the detector (such as CMOS or CCD), causing detector saturation. This results in overexposure or even artifacts in local areas of the field of view due to detector overexposure. These artifacts not only obscure the true structural information but also introduce measurement errors, severely limiting the reliability of imaging results and the accuracy of quantitative analysis.

[0003] In the prior art, the implementations closest to this invention mainly fall into two categories: Hardware optimization solutions: For example, the existing dual-linear CCD detection scheme adds an additional detector to collect unsaturated signals to compensate for saturated regions. However, this method suffers from problems such as system complexity, difficulty in dual-CCD calibration, and high cost, and its compensation effect is limited, making it impractical.

[0004] Digital image processing solutions include existing interpolation methods, dictionary-based sparse representation methods, and neural network-based image inpainting techniques. These methods are post-processing techniques, which can alleviate artifacts to some extent, but they generally suffer from common drawbacks such as loss of detail, strong dependence on data quality or quantity, and limited applicability, making it difficult to balance image realism, processing stability, and scenario versatility.

[0005] In summary, the existing technical solutions have the following limitations: 1. Hardware improvement solutions (such as dual CCDs) are costly, complex, and difficult to calibrate; 2. Digital image processing methods (such as interpolation, sparse representation, and neural networks) are prone to loss of detail and are highly dependent on the size and quality of the dataset, limiting their applicability to various scenarios. Summary of the Invention

[0006] This invention provides a method and system for suppressing saturation artifacts in optical coherence tomography images, which effectively improves imaging quality, facilitates system integration, and is cost-effective.

[0007] According to an embodiment of the present invention, a method for suppressing saturation artifacts in optical coherence tomography images is provided, comprising the following steps: The laser emitted by the light source is split by a beam splitter and then incident on the ring mirror at a preset angle; The center of the mirror surface has a light-transmitting aperture of a preset size, and the central part of the incident beam directly enters the optical path of the reference arm through the light-transmitting aperture; The ring-shaped portion of the beam is reflected by a mirror, enters the lens through the scanning system, and is finally focused onto the sample; Backscattered light returning from the sample travels back along the original optical path and enters the detector via the beam splitter.

[0008] Furthermore, the mirror filters out the central portion of the incident light from the sample arm, where the energy is more concentrated, through its central aperture, retaining only the beam from the annular region at its edge, thus creating dark-field illumination.

[0009] Furthermore, the spectrometer is controlled to perform two image acquisition operations at the same measurement location, including long exposure / high gain image acquisition and short exposure / low gain image acquisition.

[0010] Furthermore, long exposure / high gain image acquisition includes: By extending the exposure time or increasing the detector gain, the capture of light signals in low-reflection areas at the edge of the sample is enhanced, thus fully preserving edge textures and weak defect signals.

[0011] Furthermore, short-exposure / low-gain image acquisition includes: By shortening the exposure time or reducing the gain, overexposure in high-reflectivity areas can be effectively suppressed, ensuring that the structural details in high-reflectivity areas are clearly discernible.

[0012] Furthermore, long exposure / high gain image acquisition specifically includes: By using column-wise median filtering to suppress random fluctuations in normal signals, abnormally bright areas caused by sensor saturation can be accurately located. Based on the filtering results, a neighborhood window is set with the pixel as the center, and the saturated pixels are divided into three categories according to the maximum detection intensity of the detector: fully saturated, partially overexposed, and well exposed. Finally, a differentiated integration strategy is designed based on the degree of saturation.

[0013] Furthermore, differentiated integration strategies include: Good exposure areas directly preserve long exposure details; Incompletely overexposed areas are balanced by dynamic weighted fusion to account for the advantages of long and short exposures or different gains. For fully saturated areas, short exposures or low-gain data with exposure time or gain coefficient correction are used to replace and repair them, eliminating overexposure artifacts while preserving details in low-reflection areas.

[0014] Furthermore, in the boundary transition after fusion, a distance-weighted feathering algorithm based on Grassfire transform is adopted to eliminate brightness jumps at the region junctions and achieve smooth transition of the transition region.

[0015] Furthermore, the distance-weighted feathering algorithm based on Grassfire transform includes: By calculating the normalized distance from the replacement region pixels to the boundary to generate smooth weights, the correction results are gradually adjusted. The boundary pixels retain the details of the overexposed area recovery, connect the brightness of the original long exposure background, and finally eliminate artificial sharp edges to achieve smooth blending of the transition area.

[0016] According to another embodiment of the present invention, an optical coherence tomography image saturation artifact suppression system is provided, comprising: a beam splitter, a ring mirror, a reference arm, a scanning system, a lens, and a detector; wherein: The laser emitted by the light source is split by a beam splitter and then incident on the ring mirror at a preset angle; The center of the mirror surface has a light-transmitting aperture of a preset size, and the central part of the incident beam directly enters the optical path of the reference arm through the light-transmitting aperture; The ring-shaped portion of the beam is reflected by a mirror, enters the lens through the scanning system, and is finally focused onto the sample; Backscattered light returning from the sample travels back along the original optical path and enters the detector via the beam splitter.

[0017] A storage medium storing a program file capable of implementing any of the above-described methods for suppressing saturation artifacts in optical coherence tomography images.

[0018] A processor for running a program, wherein the program executes, during runtime, any of the above-mentioned methods for suppressing saturation artifacts in optical coherence tomography images.

[0019] The core innovation of the optical coherence tomography image saturation artifact suppression method and system in this invention lies in the synergistic effect of optical path optimization and adaptive image fusion to systematically solve the saturation artifact problem in high dynamic range scenes. This invention effectively eliminates saturation artifacts while fully preserving the edge structure information of low-reflection areas, significantly improving image quality and measurement accuracy. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a flowchart of the method for suppressing saturation artifacts in optical coherence tomography images according to the present invention; Figure 2 This is a structural diagram of the optical coherence tomography image saturation artifact suppression system of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Example 1 According to an embodiment of the present invention, a method for suppressing saturation artifacts in optical coherence tomography images is provided, see [link to relevant documentation]. Figure 1 This includes the following steps: The laser emitted by the light source is split by a beam splitter and then incident on the ring mirror at a preset angle; The center of the mirror surface has a light-transmitting aperture of a preset size, and the central part of the incident beam directly enters the optical path of the reference arm through the light-transmitting aperture; The ring-shaped portion of the beam is reflected by a mirror, enters the lens through the scanning system, and is finally focused onto the sample; Backscattered light returning from the sample travels back along the original optical path and enters the detector via the beam splitter.

[0024] The core innovation of the optical coherence tomography image saturation artifact suppression method in this invention lies in the synergistic effect of optical path optimization and adaptive image fusion to systematically solve the saturation artifact problem in high dynamic range scenes. This invention effectively eliminates saturation artifacts while fully preserving the edge structure information of low-reflection areas, significantly improving image quality and measurement accuracy.

[0025] The following detailed description of the optical coherence tomography image saturation artifact suppression method of the present invention is provided with specific embodiments: Existing technologies have significant shortcomings: hardware improvement solutions (such as dual detectors) suffer from complex structures and high costs; while pure image post-processing methods are prone to losing details and have weak resistance to noise and artifact interference. To address these shortcomings, this invention aims to provide a hardware-algorithm synergy method for saturation artifact suppression, which can effectively improve image quality, facilitate system integration, and is cost-effective. This method and apparatus aim to suppress artifacts at the source through innovative optical design and, combined with image fusion algorithms, achieve artifact suppression superior to existing technologies with lower cost and system complexity, while simultaneously improving overall image quality.

[0026] This invention addresses the limitations of existing methods for suppressing saturation artifacts in optical coherence tomography (OCT). When an OCT system detects highly reflective interfaces or strongly scattering samples, insufficient detector dynamic range can lead to saturation artifacts in the image, which not only reduces image quality but also weakens the accuracy of quantitative analysis.

[0027] The core of the technical solution of this invention lies in the synergistic strategy of combining hardware innovation of a ring-shaped reflector with optimization of high dynamic range image fusion algorithm.

[0028] As attached Figure 2 As shown, the OCT measurement system of this invention mainly includes a light source, a beam splitter, a ring mirror, a reference arm, a scanning system, a lens, and a detector. Its optical path works as follows: the laser emitted from the light source is split by the beam splitter and then incident on the ring mirror at a 45° angle. The mirror has a light-transmitting aperture of a specific size at its center—the central portion of the incident beam passes directly through the aperture into the reference arm's optical path; the annular portion of the beam (i.e., the portion outside the central spot) is reflected by the mirror, passes through the scanning system, and is incident on the lens, ultimately focusing onto the sample. The backscattered light returning from the sample returns along the original optical path and enters the detector via the beam splitter.

[0029] Compared to traditional beam splitters that only adjust the intensity ratio without altering the beam's spatial shape, the annular reflector used in this invention can actively control the beam shape while achieving beam splitting. Specifically, the reflector filters out the central portion of the incident light from the sample arm through its central aperture, where the energy is more concentrated, retaining only the beam from the annular region at its edge, thus creating dark-field illumination.

[0030] Because the ring light, after being converged by the focusing lens, has a larger incident angle compared to the central optical path, the incident angle distribution of the beam at the sample interface is optimized, effectively avoiding the direct reflection phenomenon that easily occurs due to near-perpendicular incident light. This characteristic significantly reduces the probability of saturation artifacts commonly found in traditional OCT systems at the optical structure level, thus improving image quality.

[0031] To address the problem of overexposure in bright areas and loss of detail in dark areas caused by an excessively large dynamic range of sample reflectance, this invention proposes acquiring long-exposure (or high-gain) and short-exposure (or low-gain) images at the same sampling location, and then using high dynamic range fusion technology to achieve complementary and enhanced image information. The specific implementation is as follows: I. Double Exposure (or Gain) Image Acquisition The spectrometer performs two image acquisition operations at the same measurement location: long exposure / high gain image acquisition, which enhances the capture of light signals in low-reflectivity areas at the sample edges by extending the exposure time or increasing the detector gain, thus preserving weak signal details such as edge textures and defects; however, artifacts are prone to occur in high-reflectivity areas due to signal saturation. Short exposure / low gain image acquisition, which effectively suppresses overexposure in high-reflectivity areas by shortening the exposure time or reducing the gain, ensures that structural details in high-reflectivity areas are clearly discernible; however, details may be lost in low-reflectivity areas at the edges due to weaker signals. Through this dual-exposure strategy, complete and detailed raw image data of both high-reflectivity and low-reflectivity areas can be obtained separately, providing a data foundation for subsequent image fusion.

[0032] II. Saturation Artifact Recognition and Image Fusion Methods For acquiring long exposures (or high gain) (I) long Used to preserve details in low-reflection areas but prone to overexposure) and short-exposure (or low-gain) images (I short This invention proposes a full-process processing framework of "column-directed filtering positioning - hierarchical quantization - difference fusion - boundary feathering" to preserve details in highly reflective areas (but may result in underexposure). The specific process is as follows: 1) Saturation artifact region extraction: Obtain long-exposure (high-gain) images of the same scene (I long (used to preserve details in low-reflection areas) and short-exposure (or low-gain) images (I short (Used to preserve details in highly reflective areas). One-dimensional median filtering is applied column-by-column to the long-exposure image: utilizing the median filtering's ability to suppress abnormally bright pixels, it highlights continuous abnormally high-value areas caused by sensor saturation (i.e., candidate overexposed areas).

[0033] 2) Saturated pixel classification: In candidate overexposed areas, a neighborhood window is defined centered on the pixel, and the pixels are classified into three levels based on the detector's maximum detection intensity (Vmax): Fully saturated pixels: The intensity of the center pixel is greater than 0.9Vmax, and the intensity of all pixels in the neighborhood is greater than 0.9Vmax (the sensor completely loses its response). Incompletely overexposed pixels: The intensity of the center pixel is >0.9Vmax, but there are pixels in the neighborhood with an intensity ≤0.9Vmax (partial signal is valid). Good exposure pixels: The intensity of both the center pixel and neighboring pixels is ≤0.9Vmax (signal is not saturated, details are intact).

[0034] 3) Adaptive Fusion Optimization: Based on the saturation pixel grading results, long and short exposure images are differentially fused. Good exposure pixels: directly retains the pixel values ​​of long exposure images (I fusion =I long ), utilizing its low noise and high detail characteristics; Fully saturated pixels: Replaced with pixel values ​​of the short-exposure image corrected for exposure time (I fusion =I short ×T long / T short ), where T long and T short These represent the long and short exposure times (gain coefficients). By scaling the short exposure signal to the theoretical brightness range of the long exposure, the true reflection intensity of the overexposed area is restored.

[0035] Incompletely overexposed pixels: A dynamic weighted fusion strategy is adopted, which combines the saturation level of the center pixel to adjust the contribution weight of long and short exposures, balancing overexposure suppression and detail preservation; I fusion =(1 α)I' long +αI short ×T long / T short The weight α reflects the saturation level of the center pixel: α = I' long / Vmax.

[0036] Among them I' long This is the average weight within the window, used to replace the intensity of the center pixel.

[0037] 4) Boundary Smoothing: Although the hierarchical fusion strategy effectively restores details in overexposed areas, there are still abrupt brightness changes between the corrected values ​​of fully saturated / partially overexposed pixels and the background area of ​​the original long-exposure image. This discontinuity can easily lead to artificial sharp edges at the boundary between the replacement area and the surrounding background, affecting the visual consistency of the image. To address this, this invention introduces a distance-weighted feathering algorithm based on Grassfire transform: by calculating the normalized distance from the replacement area pixels to the boundary to generate smoothing weights, the correction results are gradually adjusted so that the boundary pixels can retain the restored details of the overexposed areas while naturally connecting to the brightness of the original long-exposure background, ultimately eliminating artificial sharp edges and achieving smooth fusion of the transition area.

[0038] The key points and areas to be protected in this invention are: This invention relates to an artifact suppression method that integrates optical hardware structure design and image processing algorithms. Its core innovation lies in systematically solving the saturation artifact problem in high dynamic range scenes through the synergistic effect of optical path optimization and adaptive image fusion. The specific technical solution is as follows: This method first suppresses the source at the optical hardware level: by using a ring mirror as a beam splitter, the strong central beam in the sample arm optical path is physically blocked, effectively suppressing the generation of saturation artifacts from the optical path, and providing a low-noise, high-dynamic raw data foundation for subsequent image processing.

[0039] Building upon this foundation, further optimizations were made at the software algorithm level: long-exposure (or high-gain) images and short-exposure (or low-gain) images were simultaneously acquired at the same measurement location. For long-exposure (or high-gain) images, column-oriented median filtering was used to suppress random fluctuations in normal signals and accurately locate abnormally bright areas caused by sensor saturation. Based on the filtering results, a neighborhood window was set with the pixel as the center, and saturated pixels were divided into three categories according to the detector's maximum detection intensity: fully saturated, partially overexposed, and well-exposed. Finally, a differentiated fusion strategy was designed based on the degree of saturation: well-exposed areas directly retained long-exposure details; partially overexposed areas balanced the advantages of long and short exposures (or different gains) through dynamic weighted fusion; and fully saturated areas were replaced and repaired using short-exposure (or low-gain) data corrected by exposure time (or gain coefficient), thereby eliminating overexposure artifacts while preserving details in low-reflection areas. To address the boundary transition problem after fusion, a distance-weighted feathering algorithm based on Grassfire transform was further adopted to eliminate brightness jumps at the region junctions and achieve smooth transitions.

[0040] Through the synergistic effect of optical hardware spectral suppression and software adaptive fusion, this method effectively eliminates saturation artifacts while fully preserving the edge structure information of low-reflection areas, significantly improving image quality and measurement accuracy.

[0041] Compared with the prior art, the present invention has the following outstanding advantages: 1. Combining source suppression with post-processing optimization achieves more thorough artifact control. Existing technologies are mostly limited to a single approach: hardware solutions are costly and complex to calibrate, while digital processing solutions are prone to losing details or relying on large amounts of data. This invention effectively avoids direct specular reflection, which is prone to occur due to near-perpendicular incident light beams, by using a ring-shaped reflector at the source of the optical path. Combined with a fusion algorithm to optimize residual artifacts or insufficient dynamic range in software, it forms a dual guarantee of "prevention + repair," fundamentally improving the artifact suppression effect from a mechanistic perspective.

[0042] 2. It combines high practicality with low implementation cost while ensuring image quality. Compared to traditional complex hardware solutions such as dual CCDs, this technical solution only requires replacing the core beam-splitting element (using a ring mirror) and combining it with a conventional image sensor and mature algorithms to achieve the target function, thus significantly reducing the complexity of the system architecture, the difficulty of the calibration process, and the overall manufacturing cost. Furthermore, unlike solutions that rely on post-processing techniques such as interpolation, sparse representation, or neural networks, this method effectively reduces the computational burden of software post-processing through a hardware-level pre-processing mechanism, exhibiting superior performance in preserving true image details and avoiding the over-smoothing or detail distortion problems that are easily caused by traditional post-processing.

[0043] 3. Balances center artifact suppression with improved signal-to-noise ratio at the edges of the field of view. Existing methods often focus on repairing or replacing artifact areas, making it difficult to maintain overall image quality. This invention employs a long-short exposure fusion strategy. By using short exposures to suppress overexposure in high-reflectivity areas, it effectively enhances the signal-to-noise ratio and detail visibility in weak-signal areas at the edges through long exposures. This eliminates saturation artifacts while simultaneously expanding the dynamic range of the entire imaging area, achieving overall image quality optimization.

[0044] In summary, the core advantage of this invention lies in the synergy between a simple, low-cost hardware innovation and an efficient software strategy, which achieves full-process optimization from the generation mechanism to post-processing. It significantly outperforms existing technologies in terms of artifact suppression, system usability, image detail preservation, and overall imaging quality.

[0045] Example 2 According to another embodiment of the present invention, a system for suppressing saturation artifacts in optical coherence tomography images is provided, as shown in the attached figure. Figure 2 As shown, the OCT measurement system of this invention mainly includes a light source, a beam splitter, a ring mirror, a reference arm, a scanning system, a lens, and a detector. Its optical path works as follows: the laser emitted from the light source is split by the beam splitter and then incident on the ring mirror at a 45° angle. The mirror has a light-transmitting aperture of a specific size at its center—the central portion of the incident beam passes directly through the aperture into the reference arm's optical path; the annular portion of the beam (i.e., the portion outside the central spot) is reflected by the mirror, passes through the scanning system, and is incident on the lens, ultimately focusing onto the sample. The backscattered light returning from the sample returns along the original optical path and enters the detector via the beam splitter.

[0046] Compared to traditional beam splitters that only adjust the intensity ratio without altering the beam's spatial shape, the annular reflector used in this invention can actively control the beam shape while achieving beam splitting. Specifically, the reflector filters out the central portion of the incident light from the sample arm through its central aperture, where the energy is more concentrated, retaining only the beam from the annular region at its edge, thus creating dark-field illumination.

[0047] Because the ring light, after being converged by the focusing lens, has a larger incident angle compared to the central optical path, the incident angle distribution of the beam at the sample interface is optimized, effectively avoiding the direct reflection phenomenon that easily occurs due to near-perpendicular incident light. This characteristic significantly reduces the probability of saturation artifacts commonly found in traditional OCT systems at the optical structure level, thus improving image quality.

[0048] To address the problem of overexposure in bright areas and loss of detail in dark areas caused by an excessively large dynamic range of sample reflectance, this invention proposes acquiring long-exposure (or high-gain) and short-exposure (or low-gain) images at the same sampling location, and then using high dynamic range fusion technology to achieve complementary and enhanced image information. The specific implementation is as follows: I. Double Exposure (or Gain) Image Acquisition The spectrometer performs two image acquisition operations at the same measurement location: long exposure / high gain image acquisition, which enhances the capture of light signals in low-reflectivity areas at the sample edges by extending the exposure time or increasing the detector gain, thus preserving weak signal details such as edge textures and defects; however, artifacts are prone to occur in high-reflectivity areas due to signal saturation. Short exposure / low gain image acquisition, which effectively suppresses overexposure in high-reflectivity areas by shortening the exposure time or reducing the gain, ensures that structural details in high-reflectivity areas are clearly discernible; however, details may be lost in low-reflectivity areas at the edges due to weaker signals. Through this dual-exposure strategy, complete and detailed raw image data of both high-reflectivity and low-reflectivity areas can be obtained separately, providing a data foundation for subsequent image fusion.

[0049] II. Saturation Artifact Recognition and Image Fusion Methods For acquiring long exposures (or high gain) (I) long Used to preserve details in low-reflection areas but prone to overexposure) and short-exposure (or low-gain) images (I short This invention proposes a full-process processing framework of "column-directed filtering positioning - hierarchical quantization - difference fusion - boundary feathering" to preserve details in highly reflective areas (but may result in underexposure). The specific process is as follows: 1) Saturation artifact region extraction: Obtain long-exposure (high-gain) images of the same scene (I long (used to preserve details in low-reflection areas) and short-exposure (or low-gain) images (I short (Used to preserve details in highly reflective areas). One-dimensional median filtering is applied column-by-column to the long-exposure image: utilizing the median filtering's ability to suppress abnormally bright pixels, it highlights continuous abnormally high-value areas caused by sensor saturation (i.e., candidate overexposed areas).

[0050] 2) Saturated pixel classification: In candidate overexposed areas, a neighborhood window is defined centered on the pixel, and the pixels are classified into three levels based on the detector's maximum detection intensity (Vmax): Fully saturated pixels: The intensity of the center pixel is greater than 0.9Vmax, and the intensity of all pixels in the neighborhood is greater than 0.9Vmax (the sensor completely loses its response). Incompletely overexposed pixels: The intensity of the center pixel is >0.9Vmax, but there are pixels in the neighborhood with an intensity ≤0.9Vmax (partial signal is valid). Good exposure pixels: The intensity of both the center pixel and neighboring pixels is ≤0.9Vmax (signal is not saturated, details are intact).

[0051] 3) Adaptive Fusion Optimization: Based on the saturation pixel grading results, long and short exposure images are differentially fused. Good exposure pixels: directly retains the pixel values ​​of long exposure images (I fusion =I long ), utilizing its low noise and high detail characteristics; Fully saturated pixels: Replaced with pixel values ​​of the short-exposure image corrected for exposure time (I fusion =I short ×T long / T short ), where T long and T short These represent the long and short exposure times (gain coefficients). By scaling the short exposure signal to the theoretical brightness range of the long exposure, the true reflection intensity of the overexposed area is restored.

[0052] Incompletely overexposed pixels: A dynamic weighted fusion strategy is adopted, which combines the saturation level of the center pixel to adjust the contribution weight of long and short exposures, balancing overexposure suppression and detail preservation; I fusion =(1 α)I' long +αI short ×T long / T short The weight α reflects the saturation level of the center pixel: α = I' long / Vmax.

[0053] Among them I' long This is the average weight within the window, used to replace the intensity of the center pixel.

[0054] 4) Boundary Smoothing: Although the hierarchical fusion strategy effectively restores details in overexposed areas, there are still abrupt brightness changes between the corrected values ​​of fully saturated / partially overexposed pixels and the background area of ​​the original long-exposure image. This discontinuity can easily lead to artificial sharp edges at the boundary between the replacement area and the surrounding background, affecting the visual consistency of the image. To address this, this invention introduces a distance-weighted feathering algorithm based on Grassfire transform: by calculating the normalized distance from the replacement area pixels to the boundary to generate smoothing weights, the correction results are gradually adjusted so that the boundary pixels can retain the restored details of the overexposed areas while naturally connecting to the brightness of the original long-exposure background, ultimately eliminating artificial sharp edges and achieving smooth fusion of the transition area.

[0055] The key points and areas to be protected in this invention are: This invention relates to an artifact suppression method that integrates optical hardware structure design and image processing algorithms. Its core innovation lies in systematically solving the saturation artifact problem in high dynamic range scenes through the synergistic effect of optical path optimization and adaptive image fusion. The specific technical solution is as follows: This method first suppresses the source at the optical hardware level: by using a ring mirror as a beam splitter, the strong central beam in the sample arm optical path is physically blocked, effectively suppressing the generation of saturation artifacts from the optical path, and providing a low-noise, high-dynamic raw data foundation for subsequent image processing.

[0056] Building upon this foundation, further optimizations were made at the software algorithm level: long-exposure (or high-gain) images and short-exposure (or low-gain) images were simultaneously acquired at the same measurement location. For long-exposure (or high-gain) images, column-oriented median filtering was used to suppress random fluctuations in normal signals and accurately locate abnormally bright areas caused by sensor saturation. Based on the filtering results, a neighborhood window was set with the pixel as the center, and saturated pixels were divided into three categories according to the detector's maximum detection intensity: fully saturated, partially overexposed, and well-exposed. Finally, a differentiated fusion strategy was designed based on the degree of saturation: well-exposed areas directly retained long-exposure details; partially overexposed areas balanced the advantages of long and short exposures (or different gains) through dynamic weighted fusion; and fully saturated areas were replaced and repaired using short-exposure (or low-gain) data corrected by exposure time (or gain coefficient), thereby eliminating overexposure artifacts while preserving details in low-reflection areas. To address the boundary transition problem after fusion, a distance-weighted feathering algorithm based on Grassfire transform was further adopted to eliminate brightness jumps at the region junctions and achieve smooth transitions.

[0057] Through the synergistic effect of optical hardware spectral suppression and software adaptive fusion, this method effectively eliminates saturation artifacts while fully preserving the edge structure information of low-reflection areas, significantly improving image quality and measurement accuracy.

[0058] Compared with the prior art, the present invention has the following outstanding advantages: 1. Combining source suppression with post-processing optimization achieves more thorough artifact control. Existing technologies are mostly limited to a single approach: hardware solutions are costly and complex to calibrate, while digital processing solutions are prone to losing details or relying on large amounts of data. This invention effectively avoids direct specular reflection, which is prone to occur due to near-perpendicular incident light beams, by using a ring-shaped reflector at the source of the optical path. Combined with a fusion algorithm to optimize residual artifacts or insufficient dynamic range in software, it forms a dual guarantee of "prevention + repair," fundamentally improving the artifact suppression effect from a mechanistic perspective.

[0059] 2. It combines high practicality with low implementation cost while ensuring image quality. Compared to traditional complex hardware solutions such as dual CCDs, this technical solution only requires replacing the core beam-splitting element (using a ring mirror) and combining it with a conventional image sensor and mature algorithms to achieve the target function, thus significantly reducing the complexity of the system architecture, the difficulty of the calibration process, and the overall manufacturing cost. Furthermore, unlike solutions that rely on post-processing techniques such as interpolation, sparse representation, or neural networks, this method effectively reduces the computational burden of software post-processing through a hardware-level pre-processing mechanism, exhibiting superior performance in preserving true image details and avoiding the over-smoothing or detail distortion problems that are easily caused by traditional post-processing.

[0060] 3. Balances center artifact suppression with improved signal-to-noise ratio at the edges of the field of view. Existing methods often focus on repairing or replacing artifact areas, making it difficult to maintain overall image quality. This invention employs a long-short exposure fusion strategy. By using short exposures to suppress overexposure in high-reflectivity areas, it effectively enhances the signal-to-noise ratio and detail visibility in weak-signal areas at the edges through long exposures. This eliminates saturation artifacts while simultaneously expanding the dynamic range of the entire imaging area, achieving overall image quality optimization.

[0061] In summary, the core advantage of this invention lies in the synergy between a simple, low-cost hardware innovation and an efficient software strategy, which achieves full-process optimization from the generation mechanism to post-processing. It significantly outperforms existing technologies in terms of artifact suppression, system usability, image detail preservation, and overall imaging quality.

[0062] Example 3 A storage medium storing a program file capable of implementing any of the above-described methods for suppressing saturation artifacts in optical coherence tomography images.

[0063] Example 4 A processor for running a program, wherein the program executes, during runtime, any of the above-mentioned methods for suppressing saturation artifacts in optical coherence tomography images.

[0064] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0065] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0066] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The system embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of units or modules may be electrical or other forms.

[0067] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0068] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0069] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for suppressing saturation artifacts in optical coherence tomography images, characterized in that, Includes the following steps: The laser emitted by the light source is split by a beam splitter and then incident on the ring mirror at a preset angle; The center of the mirror surface has a light-transmitting aperture of a preset size, and the central part of the incident beam directly enters the optical path of the reference arm through the light-transmitting aperture; The ring-shaped portion of the beam is reflected by a mirror, enters the lens through the scanning system, and is finally focused onto the sample; Backscattered light returning from the sample travels back along the original optical path and enters the detector via the beam splitter.

2. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 1, characterized in that, The mirror filters out the central portion of the incident light from the sample arm, where the energy is concentrated, through its central aperture, retaining only the beam from the annular region at its edge, thus creating dark field illumination.

3. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 1, characterized in that, The spectrometer is controlled to perform two image acquisition operations at the same measurement location, including long exposure / high gain image acquisition and short exposure / low gain image acquisition.

4. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 3, characterized in that, Long exposure / high gain image acquisition includes: By extending the exposure time or increasing the detector gain, the capture of light signals in low-reflection areas at the edge of the sample is enhanced, thus fully preserving edge textures and weak defect signals.

5. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 3, characterized in that, Short exposure / low gain image acquisition includes: By shortening the exposure time or reducing the gain, overexposure in high-reflectivity areas can be effectively suppressed, ensuring that the structural details in high-reflectivity areas are clearly discernible.

6. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 4, characterized in that, Long exposure / high gain image acquisition specifically includes: By using column-wise median filtering to suppress random fluctuations in normal signals, abnormally bright areas caused by sensor saturation can be accurately located. Based on the filtering results, a neighborhood window is set with the pixel as the center, and the saturated pixels are divided into three categories according to the maximum detection intensity of the detector: fully saturated, partially overexposed, and well exposed. Finally, a differentiated integration strategy is designed based on the degree of saturation.

7. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 6, characterized in that, Differentiated integration strategies include: Good exposure areas directly preserve long exposure details; Incompletely overexposed areas are balanced by dynamic weighted fusion to account for the advantages of long and short exposures or different gains. For fully saturated areas, short exposures or low-gain data with exposure time or gain coefficient correction are used to replace and repair the overexposure artifacts while preserving details in low-reflection areas.

8. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 6, characterized in that, For the boundary transition after fusion, a distance-weighted feathering algorithm based on Grassfire transform is adopted to eliminate brightness jumps at the region junctions and achieve smooth transition of the transition region.

9. The method for suppressing saturation artifacts in optical coherence tomography images according to claim 8, characterized in that, Distance-weighted feathering algorithms based on Grassfire transform include: By calculating the normalized distance from the replacement region pixels to the boundary to generate smooth weights, the correction results are gradually adjusted. The boundary pixels retain the details of the overexposed area recovery, connect the brightness of the original long exposure background, and finally eliminate artificial sharp edges to achieve smooth blending of the transition area.

10. A system for suppressing saturation artifacts in optical coherence tomography images, characterized in that, include: The components include a beam splitter, a ring mirror, a reference arm, a scanning system, a lens, and a detector; among which: The laser emitted by the light source is split by a beam splitter and then incident on the ring mirror at a preset angle; The center of the mirror surface has a light-transmitting aperture of a preset size, and the central part of the incident beam directly enters the optical path of the reference arm through the light-transmitting aperture; The ring-shaped portion of the beam is reflected by a mirror, enters the lens through the scanning system, and is finally focused onto the sample; Backscattered light returning from the sample travels back along the original optical path and enters the detector via the beam splitter.

Images