Color measuring device and color measuring method for three-dimensional cultural relics

Abstract

The invention provides a three-dimensional cultural relic-oriented color measuring device and method, the device comprises an integrating sphere, a baffle plate, a comparison plate, a shading cover, a light source, an imaging lens and an imaging detector, the integrating sphere is provided with a side opening, and the surface of the integrating sphere is provided with a light inlet and a plurality of observation ports; the light inlet is located on the lower side of the integrating sphere, the light source is located at the light outlet, and the baffle is arranged above the light inlet; the inner surface of the integrating sphere, the surface of the baffle, the surface of the shading cover and the surface of the contrast plate are coated with diffuse reflection materials; therefore, the system does not need to contact the surface of the three-dimensional cultural relic to be detected for color collection, has a stable and uniform illumination environment, is not interfered by external illumination, improves the environmental adaptability of the system, and can avoid the influence of the glossiness of the surface of the object to be detected on color measurement; meanwhile, the color measurement consistency is good, the operation is convenient, and the color measurement accuracy and efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of color measurement, and in particular relates to a color measurement device and a color measurement method for three-dimensional cultural relics. Background Art

[0002] Non-contact color measurement has become a high-demand issue in fields such as cultural heritage protection, artwork authentication, medical imaging, and industrial quality control. The most widely used color evaluation method in the past was subjective evaluation. This involves visual evaluation by the human eye under a standardized light source (such as a light box) and determines the color by comparing it with a color standard. The accuracy and consistency of this method are significantly affected by the evaluator's subjective judgment, ambient lighting, viewing conditions, and surface gloss. With the advancement of science and technology, objective measurement methods have gradually replaced subjective evaluation, among which spectrophotometers are the most commonly used measurement tools. Spectrophotometers provide accurate color data by measuring the spectral distribution of sample reflection or transmission. However, they usually require the sample surface to be flat and the measurement area to have high color uniformity, which makes them unsuitable for samples with complex textures and irregular shapes. In addition, when large-scale overall color measurement of samples is required, the point-by-point measurement mode of spectrophotometers brings significant time and complexity challenges, further limiting its scope of application. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a colorimetric device and a colorimetric method for three-dimensional cultural relics, which have good measurement consistency, are easy to operate, and improve measurement accuracy and efficiency.

[0004] A colorimetric device for three-dimensional cultural relics, comprising an integrating sphere 100, a light source baffle 120, a light shielding cover 130, a light source 200, a contrast plate 300, an imaging lens 400, an imaging detector 410, and a lifting and rotating assembly;

[0005] The contrast plate 300 is arranged inside the integrating sphere 100 through a lifting and rotating assembly, and the three-dimensional cultural relic to be measured is placed on the contrast plate 300;

[0006] The outer wall of the integrating sphere 100 is provided with a plurality of observation ports, wherein an imaging lens 400 and an imaging detector 410 are placed at the position of one of the observation ports, and the imaging lens 400 is placed perpendicular to the observation port, and the imaging detector 410 is coaxially aligned with the imaging lens and directly located behind the imaging lens 400, and the remaining observation ports are shielded by a light shielding cover 130, and the inner wall of the light shielding cover 130 is coated with a diffuse reflection coating of the same material as the inner wall of the integrating sphere;

[0007] The light source 200 is disposed at the bottom of the integrating sphere 100 , and the arc-shaped light source baffle 120 is placed directly above the light source 200 . The light source 200 forms a uniform diffuse reflection light field after multiple reflections by the light source baffle 120 and the inner wall of the integrating sphere 100 .

[0008] Further, the lifting and rotating assembly includes a stepping motor 310, a support frame 320, a rotating rocker 330, and a stepping motor driver 340;

[0009] A stepper motor 310 is placed on the top of the support frame 320, and a rotating rocker 330 is connected to the bottom. The support frame 320 and the rotating rocker 330 are connected by threads, and the support frame 320 is raised and lowered by the threaded transmission between the rotating rocker 330 and the support frame 320;

[0010] The stepper motor 310 is placed at the bottom of the contrast plate 300 , and the rotating shaft of the stepper motor 310 is connected to the contrast plate 300 , and the driving shaft is connected to the stepper motor driver 340 , then the stepper motor 310 rotates under the control of the stepper motor driver 340 , thereby driving the contrast plate 300 to rotate.

[0011] Furthermore, a color measurement device for three-dimensional cultural relics further includes a side door 110;

[0012] The opening and closing of the side door 110 are respectively used to achieve the taking of the three-dimensional cultural relic to be measured and the formation of a uniform diffuse reflection light field.

[0013] Furthermore, six observation ports are opened on the outer wall of the integrating sphere 100, and the incident angles of the six observation ports relative to the center of the integrating sphere are 0°, 8°, 30°, 45°, 60°, and 90°, respectively, wherein the imaging lens 400 and the imaging detector 410 are placed at the position of the 45° observation port.

[0014] Furthermore, imaging lenses and imaging detectors are also placed at the observation ports at 0°, 8°, 30°, 60°, and 90°, so as to simultaneously capture images of the three-dimensional cultural relics to be measured from six different azimuth angles.

[0015] Furthermore, a colorimetric method for a colorimetric device for three-dimensional cultural relics comprises the following steps:

[0016] Turn on the light source switch to form a uniform and stable light environment in the integrating sphere 100;

[0017] Adjust the lifting and rotating assembly to place the comparison plate 300 at the required measuring height;

[0018] Turn on the imaging detector 410, collect data from the contrast plate 300, complete white calibration and obtain an average response value of the contrast plate in the image;

[0019] Placing the 3D cultural relic to be tested on the contrast board 300, and collecting the generated cultural relic image, wherein the contrast board is also collected as the background of the 3D cultural relic to be tested;

[0020] Calculate a correction coefficient according to the average response value of the contrast plate 300 in the collected cultural relic image and the average response value of the contrast plate 300 during white calibration, apply the correction coefficient to the cultural relic image, and obtain a color image of the three-dimensional cultural relic to be measured under a uniform lighting environment;

[0021] The lifting and rotating assembly is controlled to rotate the contrast plate 300 according to the measurement needs. After the rotation is completed, the image of the cultural relic is continuously collected, and the above-mentioned correction steps are repeated to complete the color information collection of different angles of the three-dimensional cultural relic to be measured without contacting the three-dimensional cultural relic to be measured.

[0022] By processing the color images of the 3D cultural relic to be tested collected from different angles and combining the geometric structure information of the 3D cultural relic to be tested, a 3D color model of the 3D cultural relic to be tested is generated;

[0023] After the 3D reconstruction is completed, the user can perform interactive operations on the generated 3D color model through the software interface, including rotating, scaling, and translating the model, as well as clicking on any point on the model to obtain the color information and related spectral data of that point.

[0024] Furthermore, the pixel value d of any pixel point of the color image of the 3D cultural relic to be tested under uniform illumination is sample The calculation method is as follows:

[0025]

[0026] Among them, rsp sample is the original pixel value of the 3D artifact to be tested collected by the detector, rap white is the original pixel value of the contrast plate collected by the detector, r white is the spectral reflectance of the comparison board.

[0027] Beneficial effects:

[0028] 1. The present invention provides a colorimetric device for three-dimensional cultural relics, comprising an integrating sphere, a baffle, a contrast plate, a light shielding cover, a light source, an imaging lens and an imaging detector, wherein the integrating sphere has a side opening, and a light inlet and a plurality of observation ports are arranged on the surface of the integrating sphere; the light inlet is located at the lower side of the integrating sphere, the light source is located at the position of the light outlet, and the baffle is arranged above the light inlet; the inner surface of the integrating sphere, the baffle surface, the light shielding cover surface and the contrast plate surface are coated with diffuse reflection material; it can be seen that the present invention does not need to contact the surface of the three-dimensional cultural relic to be measured for color collection, has a stable and uniform lighting environment, is not disturbed by external light, improves the environmental adaptability of the system, and can be free from the influence of the glossiness of the surface of the measured object on the color measurement; at the same time, the color measurement of the present invention has good consistency, is easy to operate, and improves the accuracy and efficiency of color measurement.

[0029] 2. The present invention provides a colorimetric device for three-dimensional cultural relics, which has a simple structure and a stable and uniform lighting environment. Through the coordinated lifting and rotating components, it can realize non-contact acquisition of all-round color information of objects within a few minutes, thereby quickly acquiring spatial color distribution information on the sample surface and ensuring high resolution of the measurement; at the same time, through a contrast plate coated with diffuse reflection material, the color temperature in the integrating sphere can be monitored and corrected in real time, providing a new idea for accurate standardized color measurement of non-contact irregular surface objects.

[0030] 3. The present invention provides a colorimetric device for three-dimensional cultural relics. A plurality of observation ports are arranged on the integrating sphere, and the position and angle of the imaging detector can be flexibly adjusted. The color information at different angles can be collected at the same time, so as to meet the measurement requirements of samples of various shapes and surfaces, improve the overall measurement efficiency, and enhance the versatility and adaptability of the system.

[0031] 4. The present invention provides a color measurement method for three-dimensional cultural relics. The contrast plate is coated with diffuse reflective white paint. It has the function of supporting the sample to be measured and serves as a color temperature monitoring tool in the integrating sphere. The structure of the color measurement system is simplified and the accuracy of color measurement is improved. The real-time monitoring and automatic correction functions reduce the need for manual intervention, improve the measurement efficiency and the degree of automation of the system. Through three-dimensional reconstruction, the color and shape information of the sample can be fully displayed from different angles, which is impossible in traditional two-dimensional images. In particular, for three-dimensional cultural relics or objects with irregular surfaces, the three-dimensional model can more accurately reflect their true appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a colorimetric device for three-dimensional cultural relics provided by the present invention;

[0033] Figure 2 A schematic structural diagram of another colorimetric device for three-dimensional cultural relics provided by the present invention. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0035] A colorimetric device for three-dimensional cultural relics, comprising an integrating sphere 100, a side door 110, a light source baffle 120, a light shielding cover 130, a light source 200, a contrast plate 300, an imaging lens 400, an imaging detector 410, and a lifting and rotating assembly; wherein the lifting and rotating assembly is installed at the bottom of the integrating sphere, and comprises a stepping motor 310, a supporting frame 320, a rotating rocker 330, and a stepping motor driver 340; the imaging detector is a visible light multi-spectral detector, or an infrared or ultraviolet detector;

[0036] The contrast plate 300 is arranged inside the integrating sphere 100 through a lifting and rotating assembly, and the three-dimensional cultural relic to be measured is placed on the contrast plate 300;

[0037] Six observation ports are provided on the outer wall of the integrating sphere 100, and the incident angles of the six observation ports relative to the center of the integrating sphere are 0°, 8°, 30°, 45°, 60°, and 90°, respectively. The imaging lens 400 and the imaging detector 410 can be installed on the corresponding observation ports according to the required angles; the first type, such as Figure 1 As shown, the imaging lens 400 and the imaging detector 410 are placed only at the position of one of the observation ports, and the imaging lens 400 is placed perpendicular to the observation port, and the imaging detector 410 is coaxially aligned with the imaging lens and directly located behind the imaging lens 400, that is, the optical axes of the imaging lens 400 and the imaging detector 410 are aligned with the center of the observation port, and the other observation ports are shielded by the light shielding cover 130, and at the same time, the inner wall of the light shielding cover 130 is coated with a diffuse reflection coating of the same material as the inner wall of the integrating sphere; the second type, as shown in FIG. Figure 2 As shown, imaging lenses and imaging detectors 410 to 415 are placed at the positions of the six observation ports, so as to simultaneously collect images of the three-dimensional cultural relics to be measured from six different azimuth angles;

[0038] The light source 200 is arranged at the bottom of the integrating sphere 100, and the arc-shaped light source baffle 120 is placed directly above the light source 200. The outgoing light of the light source 200 enters the integrating sphere through the light outlet, and the light source 200 forms a uniform diffuse reflection light field after multiple reflections by the light source baffle 120 and the inner wall of the integrating sphere 100. The inner surface of the integrating sphere, the baffle surface, the light shielding cover surface and the contrast plate surface are coated with diffuse reflection paint, thereby improving the uniformity of the illumination, thereby ensuring that the sample surface is evenly illuminated during the entire measurement process.

[0039] A stepper motor 310 is placed on the top of the support frame 320, and a rotating rocker 330 is connected to the bottom. The support frame 320 and the rotating rocker 330 are connected by threads, and the support frame 320 is raised and lowered by the threaded transmission between the rotating rocker 330 and the support frame 320; the stepper motor 310 is placed at the bottom of the contrast plate 300, and the rotating shaft of the stepper motor 310 is connected to the contrast plate 300, and the driving shaft is connected to the stepper motor driver 340, and the stepper motor 310 rotates under the control of the stepper motor driver 340, thereby driving the contrast plate 300 to rotate. In other words, the support structure of the contrast plate includes a hand crank and a driving device, and the hand crank is connected to the turntable through a gear transmission mechanism to achieve precise up and down movement of the contrast plate; the driving device of the support structure is driven by a stepper motor to control the horizontal rotation angle of the contrast plate.

[0040] The opening and closing of the side door 110 are respectively used to achieve the taking of the three-dimensional cultural relic to be measured and the formation of a uniform diffuse reflection light field.

[0041] Optionally, the colorimetric device further includes a filter and a polarizer, and the filter and the polarizer are arranged on the light path in front of the imaging detector.

[0042] Based on a colorimetric device for three-dimensional cultural relics, the present invention also provides a colorimetric method for three-dimensional cultural relics, comprising the following steps:

[0043] Step 1: Turn on the light source switch to form a uniform and stable light environment in the integrating sphere 100;

[0044] Step 2: Adjust the lifting and rotating assembly so that the comparison plate 300 is located at the required measurement height;

[0045] Step 3: close the side opening of the integrating sphere, turn on the imaging detector 410, collect data from the contrast plate 300, complete white calibration and obtain the average response value of the contrast plate in the image;

[0046] Step 4: open the side opening of the integrating sphere, place the 3D cultural relic to be tested on the contrast plate 300, close the side opening of the integrating sphere, and collect the generated cultural relic image, wherein the contrast plate is also collected as the background of the 3D cultural relic to be tested;

[0047] Step 5: Calculate a correction coefficient based on the average response value of the contrast plate 300 in the collected cultural relic image and the average response value of the contrast plate 300 during white calibration, apply the correction coefficient to the cultural relic image, and obtain a color image of the three-dimensional cultural relic to be measured under a uniform lighting environment;

[0048] It should be noted that the contrast board 200 is a standard white board coated with a uniform diffuse reflection coating and has a fixed spectral reflectance. In the uniform light field in the integrating sphere 100, the pixel values ​​of each pixel point in the imaging area of ​​the contrast board captured by the camera are consistent. The pixel values ​​of the imaging area where the contrast board is located are used for data processing to obtain the pixel value d of any pixel point of the color image of the three-dimensional cultural relic to be measured under the uniform illumination environment. sample as follows:

[0049]

[0050] Among them, rsp sample is the original pixel value of the 3D artifact to be tested collected by the detector, rap white is the original pixel value of the contrast plate collected by the detector, r white is the spectral reflectance of the comparison board. After the above image processing, the original data of the tested sample is normalized by the comparison board, the influence of light intensity change can be eliminated, the data can be standardized, and the data between different samples can be comparable, which is convenient for analysis and induction.

[0051] Step 6: Control the lifting and rotating assembly to rotate the contrast plate 300 according to the measurement needs. After the rotation is completed, continue to collect the cultural relic image, and repeat the above correction steps to complete the color information collection of different angles of the three-dimensional cultural relic to be measured without contacting the three-dimensional cultural relic to be measured;

[0052] Step 7: Processing the color images of the 3D cultural relic to be tested collected from different angles and combining the geometric structure information of the 3D cultural relic to be tested to generate a 3D color model of the 3D cultural relic to be tested;

[0053] Step 8. After the 3D reconstruction is completed, the user can perform interactive operations on the generated 3D color model through the software interface, including rotating, scaling, and translating the model, and clicking on any point on the model to obtain the color information and related spectral data of the point.

[0054] It can be seen that when shooting the sample to be tested, if the sample images at 6 azimuth angles are collected at the same time, the color information of the sample at 6 observation angles can be obtained after white correction is performed according to the corresponding contrast plates. A separate white correction is performed at each observation angle to ensure the consistency of color data at different angles, effectively reduce the color deviation caused by lighting changes or environmental influences, and further improve the accuracy of sample color measurement.

[0055] At the same time, the present invention can collect image information from multiple perspectives. Through these multi-angle data, the three-dimensional model of the sample can be accurately reconstructed, and texture mapping can be performed in combination with color information to generate a high-precision three-dimensional color model.

[0056] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A colorimetric device for three-dimensional cultural relics, characterized in that: It comprises an integrating sphere (100), a light source baffle (120), a light shielding cover (130), a light source (200), a contrast plate (300), an imaging lens (400), an imaging detector (410), and a lifting and rotating assembly; The comparison board (300) is arranged inside the integrating sphere (100) through a lifting and rotating assembly, and the three-dimensional cultural relic to be tested is placed on the comparison board (300); A plurality of observation ports are provided on the outer wall of the integrating sphere (100), an imaging lens (400) and an imaging detector (410) are placed at the position of one of the observation ports, the imaging lens (400) is placed perpendicular to the observation port, the imaging detector (410) is coaxially aligned with the imaging lens and is directly located behind the imaging lens (400), and the remaining observation ports are shielded by a light shielding cover (130), and the inner wall of the light shielding cover (130) is coated with a diffuse reflection coating made of the same material as the inner wall of the integrating sphere; The light source (200) is arranged at the bottom of the integrating sphere (100), and the arc-shaped light source baffle (120) is placed directly above the light source (200). The light source (200) forms a uniform diffuse reflection light field after multiple reflections from the light source baffle (120) and the inner wall of the integrating sphere (100).

2. A colorimetric device for three-dimensional cultural relics as claimed in claim 1, characterized in that: The lifting and rotating assembly comprises a stepping motor (310), a supporting frame (320), a rotating rocker (330), and a stepping motor drive (340); A stepper motor (310) is placed on the top of the support frame (320), and a rotating rocker (330) is connected to the bottom. The support frame (320) and the rotating rocker (330) are connected by threads, and the support frame (320) is raised and lowered by the threaded transmission between the rotating rocker (330) and the support frame (320); The stepper motor (310) is placed at the bottom of the contrast plate (300), and the rotating shaft of the stepper motor (310) is connected to the contrast plate (300), and the driving shaft is connected to the stepper motor driver (340), so that the stepper motor (310) rotates under the control of the stepper motor driver (340), thereby driving the contrast plate (300) to rotate.

3. A colorimetric device for three-dimensional cultural relics as claimed in claim 1, characterized in that: Also includes a side door (110); The opening and closing of the side door (110) are respectively used to achieve the taking of the three-dimensional cultural relic to be tested and the formation of a uniform diffuse reflection light field.

4. A colorimetric device for three-dimensional cultural relics as claimed in claim 1, characterized in that: Six observation ports are provided on the outer wall of the integrating sphere (100), and the incident angles of the six observation ports relative to the center of the integrating sphere are respectively 0°, 8°, 30°, 45°, 60°, and 90°, wherein an imaging lens (400) and an imaging detector (410) are placed at the position of the 45° observation port.

5. A colorimetric device for three-dimensional cultural relics as claimed in claim 4, characterized in that: Imaging lenses and imaging detectors are also placed at the observation ports at 0°, 8°, 30°, 60°, and 90° to simultaneously capture images of the three-dimensional cultural relics to be tested from six different azimuth angles.

6. A colorimetric method based on the colorimetric device for three-dimensional cultural relics according to claim 1, characterized in that: The following steps are involved: Turn on the light source switch to form a uniform and stable light environment in the integrating sphere (100); Adjusting the lifting and rotating assembly so that the comparison plate (300) is located at a required measuring height; Turning on the imaging detector (410), collecting data from the contrast plate (300), completing white calibration and obtaining an average response value of the contrast plate in the image; Placing the 3D cultural relic to be tested on a comparison board (300), and collecting the generated cultural relic image, wherein the comparison board is also collected as the background of the 3D cultural relic to be tested; Calculating a correction coefficient based on an average response value of the contrast plate (300) in the collected cultural relic image and an average response value of the contrast plate (300) during white calibration, applying the correction coefficient to the cultural relic image, and obtaining a color image of the three-dimensional cultural relic to be measured under a uniform lighting environment; The lifting and rotating assembly is controlled to rotate the contrast plate (300) according to measurement needs, and after the rotation is completed, the image of the cultural relic is continuously collected, and the above-mentioned correction steps are repeated to complete the color information collection of different angles of the three-dimensional cultural relic to be measured without contacting the three-dimensional cultural relic to be measured; By processing the color images of the 3D cultural relic to be tested collected from different angles and combining the geometric structure information of the 3D cultural relic to be tested, a 3D color model of the 3D cultural relic to be tested is generated; After the 3D reconstruction is completed, the user can perform interactive operations on the generated 3D color model through the software interface, including rotating, scaling, and translating the model, as well as clicking on any point on the model to obtain the color information and related spectral data of that point.

7. A colorimetric method for a colorimetric device for three-dimensional cultural relics as claimed in claim 6, characterized in that: The pixel value d of any pixel point in the color image of the three-dimensional artifact to be tested under uniform lighting conditions sample The calculation method is as follows: Among them, rsp sample is the original pixel value of the 3D artifact to be tested collected by the detector, rap white is the original pixel value of the contrast plate collected by the detector, r white is the spectral reflectance of the comparison board.

Images