Cultural relic image acquisition system combining depth-of-field stacking and HDR splicing technology

Abstract

The invention provides a cultural relic image acquisition system combining a depth-of-field stacking technology and a high dynamic range (HDR) splicing technology, and belongs to the technical field of image acquisition. According to the system, depth-of-field stacking and HDR splicing technologies are combined, focal plane positions and various exposure times are set firstly, and different exposure images are collected by each focal plane. And carrying out space alignment and brightness correction on the image by adopting an image registration algorithm based on feature points, and carrying out HDR synthesis on different exposure images of each focal plane to obtain a high dynamic range image. And calculating a definition evaluation value through a Laplace operator, and selecting the pixel with the highest definition to generate a panoramic depth image. Image feature point matching and alignment are carried out on multiple panoramic depth synthesis, seamless fusion is carried out through a smooth transition function based on weight, and the problems of splicing gaps and inconsistent brightness are eliminated. And finally, enhancing details by using a multi-scale Retinex algorithm, and performing color correction by using a standard color card to generate a high-precision and large-format cultural relic panoramic depth image.

Description

Technical Field

[0001] The present invention relates to the field of cultural relic image acquisition, and more specifically, to a high-precision cultural relic image acquisition system combining depth of field stacking and HDR stitching technology. Background Art

[0002] With the increasing demand for cultural heritage protection and research, high-resolution cultural relic image acquisition technology plays an important role in fields such as archaeology and museums. Traditional image acquisition technology has problems such as insufficient depth of field, limited dynamic range and loss of details at high magnification. The limited depth of field at high magnification leads to blurring of some areas of the image, and the camera sensor bit depth is not enough to capture complex light and shadow details and color transitions, and it is easy to lose bright and dark information in high-contrast scenes. In addition, the existing stitching methods mostly rely on lossy compression formats such as JPEG, which cannot meet the requirements of high color and detail fidelity for cultural relic image acquisition. Although depth of field stacking and HDR imaging technology have been widely used, combining the two for cultural relic image acquisition still faces many challenges, including the difficulty of multi-dimensional data alignment and fusion, multiple processing that easily leads to loss of details or color deviation, and low efficiency of high-resolution data processing. Therefore, the existing technology is insufficient in the acquisition of high-resolution cultural relic images, and innovative methods are urgently needed to meet the professional needs of fields such as archaeology and museums. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies of the prior art and to propose a high-precision cultural relic image acquisition system that combines depth of field stacking and HDR stitching technology.

[0004] On the first aspect, a high-precision cultural relic image acquisition method based on depth of field stacking and HDR stitching technology is provided, including: a multi-focal plane and multi-exposure image acquisition module, an image alignment and preprocessing module, an HDR synthesis module, a full-view depth image synthesis module, an image stitching module, and a detail enhancement and color correction module.

[0005] In the second aspect, a method for collecting cultural relics images based on the present invention is provided, and the specific steps are as follows:

[0006] Step 1: Multi-focal plane and multi-exposure image acquisition: Set a series of focal plane positions to cover all depth of field areas of the artifacts. , set various exposure times , collect images with different exposures By collecting multiple exposure images at each focal plane position, and combining multiple focal planes with multiple exposure acquisition, original image data covering full depth of field and rich light and shadow details can be obtained.

[0007] Step 2: Image alignment and preprocessing: Use feature point-based image registration algorithm to spatially align the captured images to eliminate the inconsistency caused by focal plane and exposure differences; perform brightness correction on images with different exposures to lay the foundation for HDR synthesis.

[0008] Step 3: HDR synthesis: for each focal plane Different exposure images Perform HDR synthesis to obtain high dynamic range images The synthesis process is based on a radiation response function and a weighting function to ensure accurate restoration of highlights and shadows.

[0009] Step 4: Full depth image synthesis: HDR images of all focal planes , perform depth of field stacking and synthesize a full depth image The clarity evaluation value is calculated by the Laplace operator, and the pixel with the highest clarity is selected for each pixel position to generate a full-view depth image.

[0010] Step 5, image stitching: stitch large-format cultural relic images, achieve seamless stitching through feature point matching and smooth transition function design, and eliminate stitching gaps and brightness inconsistency problems.

[0011] Step 6: Detail enhancement and color correction: Use the multi-scale Retinex algorithm to enhance the details of the full depth image; use a standard color card for color correction to ensure the accuracy of color restoration.

[0012] Preferably, step 2 comprises:

[0013] Step 2.1, spatial alignment: Use feature point-based image registration algorithms, such as SURF or ORB algorithms, to accurately align images of different focal planes and exposures to ensure the spatial consistency of multidimensional data.

[0014] Step 2.2: Brightness Correction: For Images with Different Exposures Perform radiometric response correction to eliminate the impact of exposure differences and lay the foundation for HDR synthesis.

[0015] Preferably, in step 3, HDR synthesis adopts a method based on the camera radiation response function, and the specific formula is as follows:

[0016]

[0017] in, is the inverse function of the camera’s radiation response function, is a weighting function used to reduce the impact of underexposed and overexposed areas.

[0018] Preferably, step 4 comprises:

[0019] Step 4.1: Clarity evaluation: Use the Laplacian operator to calculate the clarity evaluation value of each pixel :

[0020]

[0021] Step 4.2, pixel selection: For each pixel position , select the pixel of the focal plane image with the highest resolution:

[0022]

[0023] Preferably, step 5 comprises:

[0024] Step 5.1, feature point matching and alignment: Use feature detection and matching algorithms to calculate the transformation matrix between adjacent images to achieve precise alignment.

[0025] Step 5.2: Application of smooth transition function: Design of weight-based smooth transition function , used for pixel fusion in overlapping areas. The transition function is defined as:

[0026]

[0027] in, and Represents pixels The distance to the corresponding edge of the two images.

[0028] Step 5.3, seamless fusion: In the overlapping area, the pixel value after fusion is:

[0029]

[0030] in, and is the pixel value of the two images to be stitched.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a high-precision cultural relic image acquisition system by combining depth of field stacking technology with high dynamic range (HDR) stitching technology. The system can effectively overcome the problems of insufficient depth of field, limited dynamic range and loss of details in traditional image acquisition methods at high magnification, and achieve a comprehensive and detailed record of cultural relics. Through the combined acquisition of multi-focal planes and multi-exposure images, the system can obtain original image data covering full depth of field and containing rich light and shadow details, ensuring the clarity of the image and accurate retention of details. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a flowchart of full depth image acquisition and synthesis;

[0034] Figure 2 This is the analysis of Example 1. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0036] Embodiment 1:

[0037] The embodiment of this application first analyzes the requirements of the process of cultural relic image acquisition. The requirements for cultural relic image acquisition include high resolution, full depth of field and high dynamic range, so as to facilitate the detailed analysis and protection of cultural relics. Taking the bronze ware image provided by a museum as an example, multi-focal plane position setting, exposure time setting and HDR synthesis technology are required.

[0038] Step 1: Input multiple focal plane positions and exposure settings, and collect cultural relic images from multiple focal plane positions and different exposure time combinations, such as Figure 2 As shown, multiple groups of image data are selected;

[0039] Step 2: Input the acquired image data and use the HDR synthesis module and depth of field stacking technology to generate high-quality full-depth cultural relic images.

[0040] Through the above embodiments, the present invention can automatically collect and process cultural relic images according to the set multi-focal plane position and exposure time, generate high-quality cultural relic images with true colors, rich details and full depth of field, and significantly improve the efficiency and accuracy of cultural relic image collection.

Claims

1. A cultural relic image acquisition system combining depth of field stacking and HDR stitching technology, characterized in that: include: Combined acquisition module of multiple focal planes and multiple exposure images for setting a series of focal plane positions and exposure time , at each focal plane position Collect images at different exposures ; Image alignment and preprocessing module, used to perform spatial alignment and brightness correction on images with different focal planes and exposures, solving the spatial consistency and exposure difference problems of multi-dimensional data; HDR synthesis module for each focal plane position Different exposure images Perform HDR synthesis to obtain high dynamic range images ,The synthesis process is based on the camera radiation response function and weight function; Full depth image synthesis module for HDR images of all focal planes Perform depth of field stacking to synthesize full depth images , achieved through clarity evaluation and pixel selection; Image stitching module, used to match and align feature points of multiple panoramic depth composite images, using a smooth transition function Seamless fusion to eliminate the problems of splicing gaps and inconsistent brightness; The detail enhancement and color correction module is used to perform multi-scale Retinex detail enhancement and color correction on the full-depth image to ensure the accuracy of color restoration.

2. The cultural relics image acquisition system according to claim 1, characterized in that: The multi-focal plane and multi-exposure image combination acquisition module specifically includes: Set a range of focal plane positions , covering all depth of field areas from foreground to background of cultural relics; At each focal plane , set various exposure times ; At each focal plane Collect images with different exposures .

3. The cultural relics image acquisition system according to claim 1 or 2, characterized in that: The image alignment and preprocessing module includes: The spatial alignment unit uses a feature point-based image registration algorithm to accurately align images of different focal planes and exposures; Brightness correction unit for images with different exposures Perform radiation response correction to eliminate the effects of exposure differences.

4. The cultural relics image acquisition system according to any one of claims 1 to 3, characterized in that: The HDR synthesis module adopts the following HDR synthesis formula: in, is the inverse function of the camera’s radiation response function, is the weight function.

5. The cultural relics image acquisition system according to any one of claims 1 to 4, characterized in that: The panoramic depth image synthesis module includes: The clarity evaluation unit uses the Laplace operator to calculate the clarity evaluation value of each pixel : The pixel selection unit, for each pixel position , select the pixel of the focal plane image with the highest resolution 。 6. The cultural relics image acquisition system according to any one of claims 1 to 5, characterized in that: The image stitching module comprises: The feature point matching and alignment unit uses feature detection and matching algorithms to calculate the transformation matrix between adjacent images to achieve precise alignment; Smooth transition function application unit, design weight-based smooth transition function , used for pixel fusion in overlapping areas, the transition function is defined as: in, and Represents pixels The distance to the corresponding edge of the two images; Seamless fusion unit, in the overlapping area, the fused pixel value for: in, and is the pixel value of the two images to be stitched.

7. The cultural relics image acquisition system according to any one of claims 1 to 6, characterized in that: The detail enhancement and color correction module includes: The detail enhancement unit uses a multi-scale Retinex algorithm to enhance the details of the full depth image; The color correction unit uses a standard color card and a color correction algorithm to perform color correction on the image.

8. The cultural relics image acquisition system according to any one of claims 1 to 7, characterized in that: The system also includes a data processing module, which uses a high color depth lossless image format to process data to ensure detail fidelity and high-quality storage of the image.

9. The cultural relics image acquisition system according to any one of claims 1 to 8, characterized in that: The spatial alignment unit adopts SURF (Speeded Up Robust Features) or ORB (Oriented Fast and Rotated BRIEF) feature point detection algorithm to achieve high-precision image registration.

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