A color measurement device and method for three-dimensional cultural relics

Abstract

The application provides a kind of color measurement device and method for stereoscopic cultural relics, including integrating sphere, baffle, contrast board, light shield cover, light source, imaging lens and imaging detector, wherein the integrating sphere is provided with side opening, the surface of the integrating sphere is provided with light inlet and multiple observation ports; 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 surface of the baffle, the surface of the light shield cover and the surface of the contrast board are coated with diffuse reflection material; it can be seen that the application does not need to contact the surface of the measured stereoscopic cultural relics 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 immune to the influence of the surface gloss of the measured object on color measurement; at the same time, the color measurement of the application has good consistency, is easy to operate, and improves the accuracy and efficiency of color measurement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of color measurement, and particularly relates to a color measurement device and method for three-dimensional cultural relics. BACKGROUND

[0002] Non-contact color measurement has become a high-demand issue in the fields of cultural heritage protection, art authentication, medical imaging, and industrial quality control. The most widely used color evaluation method in the past is subjective evaluation. This involves visual assessment of the human eye under a standardized light source (such as a light box), and the color is determined by comparison with color standards. The accuracy and consistency of this method are significantly affected by the evaluator's subjective judgment, environmental lighting, observation conditions, and surface glossiness. With the advancement of science and technology, objective measurement methods have gradually replaced subjective evaluation, with spectrophotometers being the most commonly used measurement tool. Spectrophotometers provide precise color data by measuring the spectral distribution of light reflected or transmitted by a sample. 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 a sample is required, the point-by-point measurement mode of spectrophotometers poses significant time and complexity challenges, further limiting their application range. SUMMARY

[0003] To solve the above problems, the present application provides a color measurement device and method for three-dimensional cultural relics, which has good measurement consistency, is easy to operate, and improves measurement accuracy and efficiency.

[0004] A color measurement 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 the lifting and rotating assembly, and the three-dimensional cultural relics to be measured are placed on the contrast plate 300;

[0006] A plurality of observation ports are formed on the outer wall of the integrating sphere 100, one of which is positioned with the imaging lens 400 and the imaging detector 410, and the imaging lens 400 is placed vertically 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 covered with the 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 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, so that the light source 200 forms a uniform diffuse reflection light field after multiple reflections between the light source baffle 120 and the inner wall of the integrating sphere 100.

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

[0009] The stepping motor 310 is placed on the top of the support frame 320, and the rotating rocker 330 is connected to the bottom of the support frame 320. The support frame 320 and the rotating rocker 330 are connected through threads, so that the lifting and lowering of the support frame 320 are realized through the thread transmission between the rotating rocker 330 and the support frame 320.

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

[0011] Further, the color measurement device for three-dimensional cultural relics further comprises a side door 110.

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

[0013] Further, six observation ports are opened on the outer wall of the integrating sphere 100, and the incident angles of the six observation ports with respect to the center of the integrating sphere are 0°, 8°, 30°, 45°, 60°, and 90°, respectively. The position of the observation port with an angle of 45° is provided with an imaging lens 400 and an imaging detector 410.

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

[0015] Further, the color measurement method of the color measurement 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-rotating assembly to make the contrast plate 300 be at the required measurement height.

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

[0019] Place the three-dimensional cultural relics to be measured on the contrast plate 300, and collect the generated cultural relic image. The contrast plate is also collected as the background of the three-dimensional cultural relics to be measured.

[0020] 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 in the white calibration, a correction coefficient is calculated, the correction coefficient is applied to the cultural relic image, and a color image of the measured three-dimensional cultural relic under the uniform illumination environment is obtained;

[0021] According to the measurement needs, the rotation of the lifting and rotating assembly to the contrast plate 300 is controlled, the cultural relic image is continuously collected after the rotation is completed, and the above-mentioned correction step is repeated, so that the color information collection of the measured three-dimensional cultural relic at different angles is completed without contacting the measured three-dimensional cultural relic;

[0022] Through processing the color images of the measured three-dimensional cultural relic collected from different angles, the three-dimensional color model of the measured three-dimensional cultural relic is generated in combination with the geometric structure information of the measured three-dimensional cultural relic.

[0023] After the three-dimensional reconstruction is completed, the user performs interactive operation on the generated three-dimensional color model through the software interface, including rotating, scaling, translating the model, and clicking any point on the model to obtain the color information and related spectral data of the point.

[0024] Further, the pixel value d sample of any pixel point of the color image of the measured three-dimensional cultural relic under the uniform illumination environment is calculated as follows:

[0025]

[0026] Wherein, rsp sample is the original pixel value of the measured three-dimensional cultural relic collected by the detector, rap white is the original pixel value of the contrast plate collected by the detector, and r white is the spectral reflectivity of the contrast plate.

[0027] Beneficial effects:

[0028] 1. The color measurement device for three-dimensional cultural relics provided by the application comprises 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, 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 position, 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 light shielding cover and the surface of the contrast plate are coated with a diffuse reflection material; thus, it can be seen that the application does not need to contact the surface of the measured three-dimensional cultural relics for color collection, has a stable and uniform illumination environment, is not disturbed by external light, improves the environmental adaptability of the system, and can be immune to the influence of the glossiness of the surface of the measured object on color measurement; at the same time, the color measurement consistency of the application is good, the operation is convenient, and the accuracy and efficiency of color measurement are improved.

[0029] 2. This invention provides a color measurement device for three-dimensional cultural relics. It has a simple structure and comes with a stable and uniform lighting environment. With the help of the lifting and rotating components, it can achieve non-contact, all-round color information acquisition of objects within minutes, thereby quickly obtaining spatial color distribution information of the sample surface and ensuring high-resolution measurement. At the same time, the color temperature inside the integrating sphere can be monitored and corrected in real time through the contrast plate coated with diffuse reflection material, providing a new approach for accurate and standardized color measurement of non-contact irregular surface objects.

[0030] 3. This invention provides a colorimetric device for three-dimensional cultural relics. The integrating sphere is equipped with multiple observation ports, which can flexibly adjust the position and angle of the imaging detector and simultaneously collect color information from different angles. This adapts to the measurement needs of samples with various shapes and surfaces, improves the overall measurement efficiency, and enhances the versatility and adaptability of the system.

[0031] 4. This invention provides a colorimetric method for three-dimensional cultural relics. The contrast plate is coated with diffuse white paint, which, while supporting the sample being measured, also serves as a color temperature monitoring tool within the integrating sphere. This simplifies the structure of the colorimetric system, improves the accuracy of colorimetric measurements, and reduces the need for manual intervention through real-time monitoring and automatic correction functions, thereby increasing measurement efficiency and the automation level 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 to achieve in traditional two-dimensional images. Especially for three-dimensional cultural relics or objects with irregular surfaces, the three-dimensional model can more accurately reflect their true appearance. Attached Figure Description

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

[0033] Figure 2 This is a schematic diagram of another color measuring device for three-dimensional cultural relics provided by the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0035] A colorimetric device for three-dimensional cultural relics includes an integrating sphere 100, a side door 110, a light source baffle 120, a light shield 130, a light source 200, a contrast plate 300, an imaging lens 400, an imaging detector 410, and a lifting and rotating assembly. The lifting and rotating assembly is installed at the bottom of the integrating sphere and includes a stepper motor 310, a support frame 320, a rotating rocker arm 330, and a stepper motor drive 340. The imaging detector is a visible light multispectral detector, or an infrared or ultraviolet detector.

[0036] The contrast plate 300 is arranged inside the integrating sphere 100 by the lifting and rotating assembly, and the measured three-dimensional cultural relics are placed on the contrast plate 300;

[0037] Six observation openings are opened on the outer wall of the integrating sphere 100, and the incident angles of the six observation openings 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 opening according to the required angle. The first kind, as shown in the figure, only has the imaging lens 400 and the imaging detector 410 placed at the position of one of the observation openings, and the imaging lens 400 is placed vertically to the observation opening, and the imaging detector 410 is coaxially aligned with the imaging lens and directly located behind the imaging lens 400, that is, the optical axis of the imaging lens 400 and the imaging detector 410 is aligned with the center of the observation opening, and the remaining observation openings are covered by the 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. The second kind, as shown in the figure, the imaging lens and the imaging detector 410-415 are placed at the positions of the six observation openings, so as to simultaneously collect the images of the measured three-dimensional cultural relics from six different azimuth angles. Figure 1 Figure 2 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 emitted by the light source 200 enters the integrating sphere through the light outlet, and then forms a uniform diffuse light field after multiple reflections of the light source 200 through the light source baffle 120 and the inner wall of the integrating sphere 100. The inner surface of the integrating sphere, the surface of the baffle, the surface of the light shielding cover and the surface of the contrast plate are coated with a diffuse reflection coating, so as to improve the uniformity of the light and ensure that the sample surface is uniformly illuminated during the entire measurement process.

[0038] The support frame 320 has a stepping motor 310 placed at the top and a rotating rocker 330 connected at the bottom. The support frame 320 and the rotating rocker 330 are connected through threads, so that the ascending and descending of the support frame 320 are realized through the thread transmission between the rotating rocker 330 and the support frame 320. The stepping motor 310 is placed at the bottom of the contrast plate 300, and the rotating shaft of the stepping motor 310 is connected with the contrast plate 300. The driving shaft is connected with the stepping motor drive 340, so that the stepping motor 310 rotates under the control of the stepping motor drive 340, and then drives the contrast plate 300 to rotate. That is, the support structure of the contrast plate includes a hand crank and a driving device. The hand crank is connected with the rotating table through a gear transmission mechanism to realize the accurate ascending and descending of the contrast plate. The driving device of the support structure adopts a stepping motor drive to control the angle of the horizontal rotation of the contrast plate.

[0039] The opening and closing of the side door 110 are respectively used to realize the taking of the measured three-dimensional cultural relics and the formation of the uniform diffuse light field.

[0040] The opening and closing of the side door 110 are respectively used to realize the taking of the measured three-dimensional cultural relics and the formation of the uniform diffuse light field.​

[0041] Optionally, the color measurement device further comprises a filter and a polarizer, which are arranged on the light path in front of the imaging detector.

[0042] Based on the color measurement device for three-dimensional cultural relics, the application further provides a color measurement method for three-dimensional cultural relics, which comprises 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 contrast plate 300 is located at the desired measurement height;

[0045] Step 3, close the side opening of the integrating sphere, turn on the imaging detector 410, collect the contrast plate 300, complete the 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 three-dimensional cultural relic to be measured on the contrast plate 300, close the side opening of the integrating sphere, collect the generated cultural relic image, wherein the contrast plate is also collected as the background of the three-dimensional cultural relic to be measured;

[0047] Step 5, calculate the 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 in the white calibration, apply the correction coefficient to the cultural relic image, and obtain the color image of the three-dimensional cultural relic to be measured under the uniform light environment;

[0048] It should be noted that the contrast plate 200 is a standard white plate coated with a uniform diffuse reflection coating, has a fixed spectral reflectance, and in the uniform light field in the integrating sphere 100, the pixel values of each pixel point in the imaging area of the contrast plate part collected by the camera are consistent. The pixel values of the imaging area where the contrast plate is located are processed 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 light environment. sample As follows:

[0049]

[0050] Wherein, rsp sample is the original pixel value of the three-dimensional cultural relic to be measured collected by the detector, rap white is the original pixel value of the contrast plate collected by the detector, and r white is the spectral reflectance of the contrast plate. After the above image processing, the original data of the measured sample is normalized through the contrast plate, the influence of light intensity change can be eliminated, the standardized data is obtained, the data between different samples is comparable, and analysis and induction are facilitated.

[0051] Step 6, the contrast plate 300 is controlled to rotate the lifting and rotating assembly according to the measurement requirement, the image of the cultural relic is continuously collected after the rotation is completed, and the above correction step is repeated, so that the color information of the three-dimensional cultural relic at different angles is collected without contacting the three-dimensional cultural relic to be measured;

[0052] Step 7, the three-dimensional color model of the three-dimensional cultural relic to be measured is generated by processing the color images of the three-dimensional cultural relic to be measured collected at different angles and combining the geometric structure information of the three-dimensional cultural relic to be measured;

[0053] Step 8, after the three-dimensional reconstruction is completed, the user performs interactive operation on the generated three-dimensional color model through a software interface, including rotating, scaling, and translating the model, and clicking any point on the model to obtain the color information and related spectral data of the point.

[0054] Therefore, when the sample to be measured is photographed, 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 the white correction is performed according to the corresponding contrast plate respectively, the color data at different angles are ensured to be consistent by performing the white correction at each observation angle, the color deviation caused by illumination change or environmental influence is effectively reduced, and the precision of the sample color measurement is further improved.

[0055] Meanwhile, the application can collect multi-view image information, the three-dimensional model of the sample can be accurately reconstructed through the multi-angle data, and the high-precision three-dimensional color model is generated by combining the color information and performing texture mapping.

[0056] Of course, the application can have other various embodiments, and those skilled in the art can certainly make various corresponding changes and modifications according to the application without departing from the spirit and essence of the application, but these corresponding changes and modifications should belong to the protection range of the claims attached to the application.

Claims

1. A color measurement method for a stereoscopic artifact-oriented color measurement device, characterized by, The colorimeter comprises an integrating sphere (100), a light source baffle (120), a light shielding cover (130), a light source (200), a contrast board (300), an imaging lens (400), an imaging detector (410) and a lifting-rotating assembly; The contrast board (300) is arranged inside the integrating sphere (100) through the lifting-rotating assembly, and the solid object to be measured is placed on the contrast board (300); A plurality of observation openings are formed on the outer wall of the integrating sphere (100), one of the observation openings is provided with the imaging lens (400) and the imaging detector (410), the imaging lens (400) is arranged perpendicularly to the observation opening, the imaging detector (410) is coaxially aligned with the imaging lens, and the imaging detector (410) is directly located behind the imaging lens (400), and the remaining observation openings are shielded by the light shielding cover (130), and the inner wall of the light shielding cover (130) is coated with a diffuse reflection coating layer 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 arranged directly above the light source (200), so that the light source (200) forms a uniform diffuse light field after multiple reflections of the light source baffle (120) and the inner wall of the integrating sphere (100); The color measurement method comprises the following steps: Turn on the light source switch to form a uniform and stable light environment in the integrating sphere (100); Adjust the lifting-rotating assembly so that the contrast board (300) is located at the desired measurement height; Turn on the imaging detector (410) to collect the contrast board (300) and complete white calibration to obtain the average response value of the contrast board in the image; Place the solid object to be measured on the contrast board (300) and collect the generated object image, wherein the contrast board is also collected as the background of the solid object to be measured; Calculate the correction coefficient according to the average response value of the contrast board (300) in the collected object image and the average response value of the contrast board (300) in the white calibration, apply the correction coefficient to the object image, and obtain the color image of the solid object to be measured under a uniform light environment; According to the measurement needs, control the lifting-rotating assembly to rotate the contrast board (300), continue to collect the object image after the rotation is completed, and repeat the correction step to complete the collection of color information of the solid object to be measured at different angles without contacting the solid object to be measured; Process the color images of the solid object to be measured collected at different angles, combine the geometric structure information of the solid object to be measured, and generate a three-dimensional color model of the solid object to be measured; After the three-dimensional reconstruction is completed, the user can perform interactive operations on the generated three-dimensional color model through a software interface, including rotating, scaling, translating the model, and clicking any point on the model to obtain the color information and related spectral data of the point.

2. The color measurement method of the stereoscopic artifact-oriented color measurement device according to claim 1, characterized by, Pixel values of any pixel point of a color image of a stereoscopic cultural relic to be measured in a uniform light environment The calculation method is as follows: wherein, is the original pixel value of the measured stereoscopic cultural relic collected by the detector, is the original pixel value of the contrast plate collected by the detector, is the spectral reflectance of the contrast plate.

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