An imaging colorimetric measurement method and a measuring device based on the same

Abstract

The present application relates to a kind of imaging colorimetric measurement method and device, its measurement method includes: a) the object to be measured is placed in front of imaging lens;B) the light of the object to be measured focused by imaging lens is divided into two beams by a light splitting system, first beam of light is introduced to two-dimensional image sensor;Second beam of light is introduced to spectral measurement equipment and carries out spectral distribution data acquisition;C) noise calibration piece shields first beam of light, two-dimensional image sensor acquires noise data;D) first beam of light passes through first band-pass filter, two-dimensional image sensor acquires image data, and deducts the noise data obtained in c), obtains first band-pass filter data matrix;E) repeat d), replace band-pass filter, obtain n band-pass filter data matrix;F) each band-pass filter data matrix is converted and calibrated as tristimulus value;G) according to the spectral distribution data in b), real-time calibration is carried out to tristimulus value, the chroma value of image is calculated and chromaticity image is generated;H) output chroma value, display or store chromaticity image.

Description

Technical Field

[0001] This invention pertains to color measurement technology, specifically to a method and apparatus that combines spectral analysis and filter imaging technology for measuring and analyzing imaging colorimetry. Background Technology

[0002] With the continuous development of technology, people have placed higher demands on the accuracy and efficiency of color measurement. Traditional color measurement instruments are mainly divided into imaging colorimeters and spectral colorimeters, each with its own advantages and disadvantages, but each has certain limitations in some application scenarios.

[0003] Imaging colorimeters use image sensors (such as CCD or CMOS) to capture images of the object being measured and pass them through a bandpass filter (usually with a...). The image is filtered by a color space matching filter, and the brightness and color information of each pixel in the image are analyzed to obtain the brightness and color distribution of the object surface.

[0004] The main advantage of imaging colorimeters is their fast measurement speed. They can simultaneously measure the brightness and color information of multiple points on an object's surface, enabling area array measurement and quickly acquiring information such as the brightness / color uniformity of an object's surface. They are suitable for online inspection in mass production.

[0005] However, imaging colorimeters have relatively low measurement accuracy, limited by the characteristics of the filters and the resolution of the image sensor. Especially when measuring objects with complex spectral reflectance characteristics, the inability of the filters to perfectly match the spectral characteristics of these light sources or objects leads to significant measurement errors. Furthermore, traditional imaging colorimeters typically do not provide spectral information, limiting their applications in color analysis and color matching. For example, in the field of LED lighting, simply measuring chromaticity coordinates is insufficient to comprehensively assess the spectral quality of LEDs, while spectral information is crucial for evaluating parameters such as color rendering index (CRI) and color temperature.

[0006] A spectral colorimeter, also known as a spectroradiometer, uses spectral analysis techniques to measure the radiant intensity of an object or light source at different wavelengths, thereby obtaining spectral power distribution data. Then, tristimulus values ​​and chromaticity coordinates are calculated according to the CIE standard chromaticity observer function. Spectral colorimeters offer higher measurement accuracy and more comprehensive spectral information, enabling more accurate measurement of various light sources, including narrow-spectrum sources and objects with complex spectra. They can provide important color parameters such as spectral power distribution and color temperature (CCT).

[0007] However, the spectral colorimeter can only make point or small area measurement, and cannot quickly obtain the overall brightness / colorimetric distribution of the object surface. In applications requiring detection of the color uniformity of the object surface, such as quality detection of displays and televisions, color and brightness distribution measurement of automotive interior lighting, etc., the efficiency is low, and multiple scans and splicing are required to obtain complete image information.

[0008] In recent years, some researchers have tried to combine imaging technology and spectral technology, such as multispectral imaging technology, by using multiple narrow-band filters or tunable filters to obtain images of an object at different wavelengths, and then performing spectral reconstruction to obtain spectral information of the object. However, this method still has some problems, such as limited spectral resolution, complex data processing, high cost, etc. Although the multispectral imaging technology combines the advantages of imaging and spectral technology to some extent, since the multispectral imaging uses a limited number of narrow-band filters, the spectral resolution is limited by the number and bandwidth of the filters. The larger the spectral interval between adjacent filters, the lower the spectral resolution, and it is difficult to capture the fine structure of the spectrum. At the same time, multispectral imaging needs to process image data of multiple wavelength channels, and the data volume is large. The calculation of the spectral reconstruction algorithm is also complex, which consumes a large amount of computing resources and time. SUMMARY

[0009] To solve the above problems, the present application proposes a new type of imaging colorimetric measurement device. The present application combines the high-efficiency area array measurement capability of the imaging colorimeter and the high-precision spectral measurement capability of the spectral colorimeter, overcoming the limitations of traditional color measurement technology.

[0010] The technical scheme of the present application includes an imaging colorimetric measurement method, which comprises the following steps:

[0011] a) placing the object to be measured at a set distance in front of the imaging lens;

[0012] b) the imaging lens focuses the light of the object to be measured, which is divided into a first light beam and a second light beam by a light splitting system, the first light beam is introduced into a two-dimensional image sensor, and the second light beam is introduced into a spectral measurement device and performs spectral distribution data acquisition;

[0013] c) placing a noise calibration sheet in the light path of the first light beam to block the light, thereby using the two-dimensional image sensor to acquire noise data;

[0014] d) the first light beam is introduced into the two-dimensional image sensor after passing through the first band-pass filter from the light splitting system, the two-dimensional image sensor is used to acquire image data, and the noise data obtained in step c) is deducted to obtain a first band-pass filter data matrix D1;

[0015] e) repeating step c) and d) or repeating step d) to replace the first band-pass filter with a second band-pass filter, a third band-pass filter, …, an n-th band-pass filter in sequence to obtain several band-pass filter data matrices, which are respectively a second band-pass filter data matrix D2, a third band-pass filter data matrix D3, an N-th band-pass filter data matrix D n , wherein n is greater than or equal to 3;

[0016] f) converting and calibrating each band-pass filter data matrix into tristimulus values to complete the initialization calibration;

[0017] g) performing coefficient correction on the tristimulus values according to the spectral distribution data collected by the spectral measurement device in step b) to complete the real-time calibration, and calculating the chrominance values of each pixel in the image and generating a chromatic image;

[0018] h) outputting the chrominance values through an output module and converting them into , or values in a color space to display or store the chromatic image.

[0019] In one embodiment, in steps c) to e), the first band-pass filter, the second band-pass filter, the third band-pass filter, …, the n-th band-pass filter are collectively referred to as band-pass filters, the noise calibration plate and the band-pass filters are distributed on a filter disc of a filter module, and the noise calibration plate and / or one of the band-pass filters are located in the light path of the first light beam by controlling the rotation or movement of the filter disc, so that the first light beam passes through one of the band-pass filters and / or the noise calibration plate and is introduced into the two-dimensional image sensor.

[0020] In one embodiment, in step f), each band-pass filter data matrix is calibrated into tristimulus values, and the tristimulus values are respectively denoted as , , The calibration formula is as follows:

[0021]

[0022] , wherein , M c is the coefficient matrix of the initialization calibration corresponding to the n band-pass filters.

[0023] In one embodiment, in step g), the tristimulus values are calibrated again according to the spectral distribution data collected by the spectral measurement device, and the tristimulus values are respectively denoted as , The formula is as follows:

[0024]

[0025] Wherein, is the average value of the tristimulus value obtained by the spectral data collected by the spectral measurement device through the chrominance integral equation;

[0026] The calibration coefficient value is obtained by the above formula The calibration coefficient value, and the The tristimulus value of each pixel in the image is again subjected to real-time calibration of the coefficient.

[0027] The technical scheme of the present application further comprises:

[0028] An imaging colorimetric measurement device for implementing the above imaging colorimetric measurement method, comprising: an imaging lens, a light splitting system, a two-dimensional image sensor, a spectral measurement device, and a light filtering module; the imaging lens is used to focus the light of the object to be measured and guide it into the light splitting system; the light splitting system splits the light of the object to be measured into a first light beam and a second light beam, the first light beam is introduced into the two-dimensional image sensor after passing through the light filtering module, and the second light beam is focused by the first focusing lens and introduced into the spectral measurement device; the light filtering module is provided with at least one noise calibration sheet and a plurality of bandpass filters for colorimetric measurement; the two-dimensional image sensor is used to receive the filtered light and convert it into a digital image; the spectral measurement device is used for spectral measurement to obtain spectral data.

[0029] In one embodiment, the light splitting system is a semi-transparent semi-reflective light splitting mirror or a semi-transparent semi-reflective light splitting prism, which is used to split the light collected by the imaging lens into the first light beam and the second light beam.

[0030] In one embodiment, the light filtering module comprises a main filter disc, the main filter disc is provided with a plurality of holes, at least one of the holes is provided with the noise calibration sheet, and the remaining holes are respectively provided with a plurality of bandpass filters for colorimetric measurement; the noise calibration sheet is made of pure black material with a reflectivity lower than 1%, which is used to collect noise data before each color measurement, and the noise data is deducted from the subsequent measurement results to improve the measurement accuracy.

[0031] ​​​​​​​​In one embodiment, the light filtering module comprises a main light filtering disc and an ND light filtering disc, each of which is provided with a plurality of holes, each of the holes of the main light filtering disc is provided with a plurality of bandpass filters for colorimetric measurement, one of the holes of the ND light filtering disc is provided with the noise calibration sheet, and each of the remaining holes of the ND light filtering disc is provided with an ND filter, and the ND filters of different holes have different optical densities; the noise calibration sheet is made of pure black material with a reflectivity lower than 1%, and is used to collect noise data before each color measurement and deduct the noise data from subsequent measurement results to improve measurement accuracy.

[0032] In one embodiment, the collimating lens and the second focusing lens are further included; the collimating lens is arranged in the light path between the light splitting system and the light filtering module, or arranged in the light path between the imaging lens and the light splitting system, and is used to convert the light introduced by the imaging lens into collimated light; the second focusing lens is arranged between the light filtering module and the two-dimensional image sensor, and is used to refocus the collimated light modulated by the light filtering module to the imaging surface of the two-dimensional image sensor.

[0033] In one embodiment, the master control system is further included, which is used to control the cooperative work of the components, process the image and spectral data collected by the two-dimensional image sensor and the spectral measurement device, and output the final colorimetric analysis result and the colorized image; the master control system comprises a processor, a memory and an input / output interface; the processor is used to execute the preset program instructions, control the cooperative work of the imaging lens, the light splitting system, the light filtering module, the two-dimensional image sensor and the spectral measurement device, and process and analyze the collected digital image and spectral data; the memory is used to store the program instructions and the collected data; the input / output interface is used to communicate with external devices; the data processing performed by the master control system comprises:

[0034] a) pre-processing the image collected by the two-dimensional image sensor, including bad pixel correction, dark current correction and gain correction, etc.;

[0035] b) extracting the image data of the corresponding color channel from the image collected by the two-dimensional image sensor according to the type of the bandpass filter of the light filtering module;

[0036] c) correcting the spectral data collected by the spectral measurement device, including dark current correction, background noise correction and wavelength correction, etc.;

[0037] d) calculating the colorimetric value of each pixel in the image and generating a colorized image according to the extracted image data and spectral data;

[0038] e) converting the calculated colorimetric values into values in the XYZ color space or other color space; 、 、 or other color space;

[0039] f) outputting the colorimetric analysis results and the colorimetric image according to the user's settings, and displaying or storing them.

[0040] In one embodiment, the spectral measurement device comprises one of the following two implementations:

[0041] a) Fiber coupling mode: a first focusing lens arranged at the rear end of the light splitting system focuses and guides the second light beam into an optical fiber; the optical fiber is used to conduct the light beam to an optical fiber spectrometer; the optical fiber spectrometer is used to perform spectral analysis on the light beam.

[0042] b) Free space optical path mode: the first focusing lens arranged at the rear end of the light splitting system performs optical processing on the second light beam, so that it is incident on a spectral illuminometer at a suitable angle and spot size; the spectral illuminometer is used to perform spectral analysis on the light beam.

[0043] In one embodiment, the first focusing lens comprises one or more lenses for collimation, focusing or converging of the light beam, so as to improve the spectral resolution and signal-to-noise ratio.

[0044] The present application combines the area array measurement capability of XYZ imaging colorimeter and the high-precision spectral measurement capability of spectral colorimeter, divides the optical path into two parallel data streams of image sensor and spectral measurement device through a light splitting system, can simultaneously and quickly obtain the colorimetric distribution information and high-precision spectral information of the surface of an object, realizes real-time fusion of pixel-level colorimetric imaging and high-precision spectral correction, overcomes the limitations of traditional colorimetric measurement devices, improves the efficiency and precision of color measurement and analysis, realizes real-time calibration of image sensor data, and overcomes the complex operation of previous imaging colorimetric measurement devices which need to be calibrated after starting up.

[0045] The present application creatively adds a noise calibration sheet to the light filtering module, the noise calibration sheet is made of pure black material with reflectivity lower than 1%, adding a noise calibration sheet to the light filtering module can measure the current noise before each measurement and deduct the noise, or even use the noise calibration sheet to deduct the noise before using each band-pass filter. Overcomes the noise calibration deduction only needed during calibration of the previous colorimetric measurement device, greatly improves the timeliness of noise data, and further ensures the accuracy of the measurement data. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is an imaging colorimetric measurement device according to Embodiment 1 of the present application.

[0047] Figure 2 Measurement flow chart of an imaging colorimetric measurement device according to an embodiment of the present application.

[0048] Figure 3 Schematic diagram of an imaging colorimetric measurement device according to Embodiment 2 of the present application.

[0049] Figure 4 Schematic diagram of an imaging colorimetric measurement device according to Embodiment 4 of the present application.

[0050] Figure 5 Schematic diagram of an imaging colorimetric measurement device according to Embodiment 8 of the present application.

[0051] Figure 6 Schematic diagram of an imaging colorimetric measurement device according to Embodiment 9 of the present application.

[0052] Figure 7 Schematic diagram of a filter switching device driven by a two-dimensional motor.

[0053] Wherein: 1 imaging lens, 2 light splitting system, 3 two-dimensional image sensor, 4 first focusing lens, 5 spectral measurement device, 51 spectral illuminometer, 6 main filter disc, 601 five-hole main filter disc, 611 ND filter disc, 7 main control system, 8 optical fiber, 9 main filter disc driving mechanism, 92 ND filter disc driving mechanism, 10 upper computer, 11 measured object, 131 x-axis motor, 132 y-axis motor. DETAILED DESCRIPTION

[0054] Embodiment 1

[0055] The embodiment discloses an imaging colorimetric measurement device which is composed of an imaging lens 1, a light splitting system 2, a two-dimensional image sensor 3, a first focusing lens 4, a spectral measurement device 51, a main filter disc 6, a main control system 7, an optical fiber 8, a main filter disc driving mechanism 9, and a host computer 10. The spectral measurement device in the embodiment is a fiber-optic spectrometer 5. Light emitted (or reflected) by a measured object 11 is focused by the imaging lens 1 and then incident on the light splitting system 2. In the embodiment, the light splitting system 2 adopts a semi-transparent and semi-reflective light splitting mirror, which splits the incident light into two beams, i.e., a first light beam and a second light beam. The light of the first light beam continues to propagate after being transmitted through the light splitting mirror and is incident on the main filter disc 6. The main filter disc 6 is provided with a plurality of bandpass filters, i.e., a first bandpass filter, a second bandpass filter, and a third bandpass filter, and a noise calibration sheet. The first bandpass filter in the embodiment is a cieX filter, the second bandpass filter is a cie Y filter, and the third bandpass filter is a cie Z filter. In other embodiments, the bandpass filters can also be the R, G, and B filters described in Embodiment 3. The noise calibration sheet is a mirror made of pure black material and has a reflectivity of less than 1%, which is close to a full black mirror. In the embodiment, the noise calibration sheet uses a carbon nanometer super-black coating and has a reflectivity of less than 0.2%. The signal collected by the two-dimensional image sensor 3 is used as noise and is removed in the subsequent measurement results, thereby improving the detection accuracy. The main filter disc driving mechanism 9 controls the rotation of the main filter disc 6 to select different bandpass filters or the noise calibration sheet. After being selected by the bandpass filter, the light finally reaches the two-dimensional image sensor 3. The two-dimensional image sensor 3 in the embodiment is a black-and-white sensor, and in other embodiments, it can also be a color sensor. The two-dimensional image sensor 3 converts the received optical signal into an electrical signal to form a digital image. The second light beam is reflected by the light splitting mirror and then incident on the first focusing lens 4. The first focusing lens 4 focuses the second light beam and efficiently couples it into the optical fiber 8. The optical fiber 8 transmits the light to the spectral measurement device 5. In the embodiment, the spectral measurement device 5 is a fiber-optic spectrometer which performs spectral analysis on the received light to obtain spectral data. The main control system 7 is responsible for coordinating the work of various components, including controlling the rotation of the main filter disc 6, controlling and collecting the two-dimensional image sensor 3, collecting the spectral data of the spectral measurement device 5, and processing and analyzing the collected digital image and spectral data. The host computer 10 is used to display the measurement results and set the measurement parameters.

[0056] The master control system 7 includes a processor, a memory, and an input / output interface; the processor is used to execute preset program instructions, control the cooperative work of the imaging lens 1, the light splitting system 2, the light filtering module, the two-dimensional image sensor 3, and the spectral measurement device 5, and process and analyze the collected digital image data and spectral data; the memory is used to store program instructions and collected data; the input / output interface is used to communicate with external devices (such as the host computer 10);

[0057] The data processing performed by the master control system 7 includes:

[0058] a) Image preprocessing: the original image collected by the two-dimensional image sensor is preprocessed to improve the image quality. The preprocessing steps include: ① bad pixel correction: detecting and repairing bad pixels (such as pixels with abnormal brightness) in the image. ② Dark current correction: deducting the dark current signal generated by the sensor itself. ③ Gain correction: gain adjustment is performed on the image to compensate for the non-uniformity of the sensor sensitivity. ④ Imaging lens shadow correction: compensating for the brightness attenuation of the image edge caused by the imaging lens.

[0059] b) Color channel extraction: according to the state of the light filtering module (i.e. the currently used band-pass filter), the image data of the corresponding color channel is extracted from the preprocessed image. For example, when the cie X filter is used, the X channel image data is extracted; when the cie Y filter is used, the Y channel image data is extracted; when the cie Z filter is used, the Z channel image data is extracted.

[0060] c) Spectral data correction: the original spectral data collected by the spectral measurement device 5 is corrected to improve the accuracy of the spectral data. The correction steps include: ① Dark current correction: deducting the dark current signal generated by the spectral measurement device 5 itself. ② Background noise correction: deducting the ambient light or other noise signals. ③ Wavelength correction: correcting the wavelength error of the spectral measurement device 5. ④ Spectral responsivity correction: correcting the response difference of the spectral measurement device to different wavelengths of light.

[0061] d) Chroma value calculation and image generation: according to the extracted image data (X, Y, Z) and spectral data, the chroma value of each pixel in the image is calculated, and the chromatic image is generated. And using the spectral data of the spectral measurement device 5 to calculate The tristimulus value.

[0062] e) Color space conversion: converting the calculated chroma value into different color spaces to meet different application requirements. Commonly used color spaces include 、 、 .

[0063] f) Result output: according to the user's settings, output the colorimetric analysis results (such as color coordinates, color difference, uniformity, etc.) and the colorized image to an external device for display or storage. The output format can be text, image, chart, etc.

[0064] As shown in Figure 2 , the embodiment also discloses an imaging colorimetric measurement method for the imaging colorimetric measurement, and the specific operation steps are as follows:

[0065] a) Place the object to be measured 11 at a certain distance in front of the imaging lens 1.

[0066] b) The light rays of the object to be measured 11 are focused by the imaging lens 1 and then split into two beams of light by a light splitting system, the first beam of light is used for transmission to a two-dimensional image sensor, and the second beam of light is used for transmission to a spectral measurement device 5 for spectral data acquisition.

[0067] c) The first beam of light is introduced into the two-dimensional image sensor after passing through a noise calibration sheet from the light splitting system, so as to use the two-dimensional image sensor to acquire noise data.

[0068] d) The first beam of light is transmitted to the two-dimensional image sensor after passing through the first band-pass filter from the light splitting system, and the two-dimensional image sensor acquires image data and deducts the noise data obtained in step b), to obtain a first band-pass filter data matrix D1.

[0069] e) Repeat steps c) and d), and sequentially replace the first band-pass filter with a second band-pass filter and a third band-pass filter, to obtain a second band-pass filter data matrix D2 and a third band-pass filter data matrix D3.

[0070] In this embodiment, the first band-pass filter is a cie X filter, the second band-pass filter is a cie Y filter, and the third band-pass filter is a cie Z filter.

[0071] f) Convert and calibrate the first band-pass filter data matrix D1, the second band-pass filter data matrix D2, and the third band-pass filter data matrix D3 into tristimulus values; and record the tristimulus values as , , , respectively, and the calibration formula is as follows:

[0072]

[0073] wherein, M c is a coefficient matrix of the initial calibration corresponding to the three band-pass filters.

[0074] g) According to the spectral distribution data collected by the spectral measurement device 5 in step b), the tristimulus values are real-time calibrated by a coefficient, and the tristimulus values in this step are respectively denoted as , , , and the chroma values of each pixel in the image are calculated, and a chromatic image is generated. Wherein, the formula for real-time calibration of tristimulus values is as follows:

[0075]

[0076] Wherein, , , is the average value of the tristimulus values calculated by using the spectral data of the measurement area collected by the spectral measurement device;

[0077] The calibration coefficient value is obtained by the above formula , , , and the , , calibration coefficient value is used to real-time calibrate the coefficient of tristimulus values of each pixel in the image in turn.

[0078] h) The chroma values are output through the output module, and are converted into , or color space values, and the chromatic image is displayed or stored.

[0079] In steps c) to e), since the noise calibration sheet, the first band-pass filter, the second band-pass filter and the third band-pass filter of the embodiment are annularly distributed on the main filter disc 6 of the filter module, one of the noise calibration sheet, the first band-pass filter, the second band-pass filter and the third band-pass filter is located in the light path of the first light beam by controlling the rotation of the main filter disc 6, so that the first light beam is transmitted to the two-dimensional image sensor through one of the noise calibration sheet, the first band-pass filter, the second band-pass filter and the third band-pass filter. In order to facilitate the two-dimensional image sensor to collect two-dimensional imaging data of the light passing through the corresponding band-pass filter or the noise calibration sheet.

[0080] The noise calibration plate is made of pure black material with a carbon nanotube ultra-black coating and a reflectivity of less than 0.2%, approaching the appearance of a completely black lens. The noise calibration plate can perform noise detection before a single measurement and discard the results from all subsequent bandpass filter measurements, improving detection accuracy. Furthermore, by repeating steps c) and d), the noise calibration plate can be switched to before each bandpass filter switch, thus denoising before each bandpass filter's filtering process, significantly improving the timeliness of noise data and ensuring the accuracy of the measurement data.

[0081] In this embodiment, the main filter disc 6 and the main filter disc drive mechanism 9 together form a filtering module. The main control system 7 controls the main filter disc drive mechanism 9, thereby driving the main filter disc 6 to rotate and switch one of the first bandpass filter, the second bandpass filter, the third bandpass filter, and the noise calibration filter in the optical path of the first beam, thus achieving the purpose of filtering. The main filter disc 6 can be driven to rotate by an electric main filter disc drive mechanism 9, or it can be manually rotated to switch the noise calibration filter, the first bandpass filter, the second bandpass filter, and the third bandpass filter.

[0082] In this embodiment, the main control system 7 is connected to the host computer 10. The host computer 10 starts the main control system 7 and outputs the chromaticity value described in step h) of embodiment 1. At this time, the output module of step h) refers to the host computer, and the host computer also converts the chromaticity value into... , or The values ​​of the color space, and how to display or store the colorized image.

[0083] Example 2

[0084] like Figure 3 As shown, compared with Embodiment 1, the main filter disc 6 is replaced with a five-hole main filter disc 601. The five-hole main filter disc 601 has five holes, in which a CIE XR filter, a CIE XB filter, a CIE Y filter, a CIE Z filter and a noise calibration plate are installed in sequence. All other devices are the same as in Embodiment 1.

[0085] Compared to Example 1, in this embodiment, the CIE X filter is replaced by a CIE Xr filter and a CIE Xb filter, and the X value is obtained by a weighted sum of the Xr and Xb values. Therefore, there are four bandpass filters, namely the first bandpass filter to the fourth bandpass filter.

[0086] Because the band-pass filter combination of the embodiment is changed from cie X, cie Y, cie Z filter to cie Xr, cie Xb, cie Y, cie Z filter, four band-pass filter data matrices are obtained, which are first band-pass filter data matrix D1, second band-pass filter data matrix D2, third band-pass filter data matrix D3 and fourth band-pass filter data matrix D4, and the four band-pass filter data matrices are converted and calibrated into three stimulus values, and the three stimulus values are recorded as respectively. , , The calibration formula is as follows:

[0087]

[0088] wherein, M c is the coefficient matrix of the initialization calibration corresponding to the four band-pass filters.

[0089] As the embodiment 2 of the present application, the specific operation steps of the colorimetric measurement using the imaging colorimetric measurement device are as follows:

[0090] a) The object to be measured 11 is placed at a set distance in front of the imaging lens 1.

[0091] b) The light rays of the object to be measured 11 are focused by the imaging lens 1 and are divided into two beams after passing through a light splitting system, the first beam is used for transmission to the two-dimensional image sensor, and the second beam is used for transmission to the spectral measurement device 5 for spectral data acquisition.

[0092] c) The host computer 10 starts the main control system 7 to control the main filter disc driving mechanism 9 to rotate the main filter disc 6 to the noise calibration piece position, and the first beam transmits the two-dimensional image sensor after passing through a noise calibration piece, so that the two-dimensional image sensor acquires noise data.

[0093] d) The main filter disc driving mechanism 9 is controlled to rotate the main filter disc 6 to the first band-pass filter position, and the two-dimensional image sensor 3 is used to acquire the image, and the noise data obtained in step b) is deducted to obtain the first band-pass filter data matrix D1.

[0094] e) Repeat steps c) and d), and sequentially replace the first band-pass filter with the second band-pass filter, the third band-pass filter and the fourth band-pass filter to obtain the second band-pass filter data matrix D2, the third band-pass filter data matrix D3 and the fourth band-pass filter data matrix D4.

[0095] In this embodiment, the first band-pass filter is a cie Xr filter, the second band-pass filter is a cie Xb filter, the third band-pass filter is a cie Y filter, and the fourth band-pass filter is a cie Z filter.

[0096] f) correcting to obtain tristimulus values.

[0097] g) calculating the chrominance values of each pixel in the image and generating a chrominance image.

[0098] h) outputting the chrominance values to the host computer 10 through the output module, converting them into , or values of a color space, and displaying or storing the chrominance image.

[0099] Embodiment 3

[0100] In this embodiment, the four holes of the main filter disc 6 are respectively provided with an R filter, a G filter, a B filter, and a noise calibration piece, and the other devices are the same as in Embodiment 1. The device diagram is not drawn.

[0101] In this embodiment, the first band-pass filter is an R filter, the second band-pass filter is a G filter, and the third band-pass filter is a B filter.

[0102] As Embodiment 3 of the present application, the specific operation steps of colorimetric measurement using the imaging colorimetric measurement device are as follows:

[0103] a) placing the object to be measured 11 at a specified distance in front of the imaging lens 1.

[0104] b) focusing the light rays of the object to be measured 11 through a light splitting system, the first beam of light is used to transmit to the two-dimensional image sensor, and the second beam of light is used to transmit to the spectral measurement device 5 for spectral data acquisition;

[0105] c) starting the main control system 7 through the host computer 10, controlling the main filter disc driving mechanism 9 to rotate the main filter disc 6 to the noise calibration piece in the light path of the first beam of light, and the first beam of light transmits to the two-dimensional image sensor through the noise calibration piece, so that the two-dimensional image sensor acquires noise data;

[0106] d) controlling the main filter disc driving mechanism 9 to rotate the main filter disc 6 to the first band-pass filter position, using the two-dimensional image sensor 3 to acquire an image, and subtracting the noise data obtained in step c) to obtain a first band-pass filter data matrix D1.

[0107] e) Repeat steps c), d), and sequentially replace the first band-pass filter with the second band-pass filter and the third band-pass filter to obtain a second band-pass filtered data matrix D2 and a third band-pass filtered data matrix D3.

[0108] f) Correct the obtained data matrix D according to the correction coefficient matrix to obtain a corrected data matrix D'. tristimulus values.

[0109] g) Calculate the chroma values of each pixel in the image and generate a chroma image.

[0110] h) Output the chroma values to the host computer 10 through the output module, convert them into , or values of a color space, and display or store the chroma image.

[0111] Embodiment 4

[0112] As shown in Figure 4 , the difference between this embodiment and embodiment 1 is that an ND filter disc 611 is placed behind the main filter disc 6, and the ND filter disc 611 is provided with ND filters of different optical densities, while the noise calibration disc is placed on the ND filter disc 611 instead of being placed on the main filter disc 6. The main filter disc 6 and the ND filter disc 611 of this embodiment together constitute a filter module.

[0113] Compared with embodiment 1, the ND filters of different optical densities can be selected according to the light intensity of the measured object, and then the light intensity entering the two-dimensional image sensor 3 is adjusted, so that more accurate (X, Y, Z) brightness is measured, and thus more accurate chroma is measured.

[0114] As embodiment 4 of the present application, the specific operation steps of using the imaging chroma measurement device to measure chroma are as follows:

[0115] a) Place the measured object 11 at a set distance in front of the imaging lens 1.

[0116] b) The light rays of the measured object 11 are focused by the imaging lens 1 and split into two beams of light by a light splitting system, the first beam of light is used to transmit to the two-dimensional image sensor, and the second beam of light is used to transmit to the spectral measurement device 5 for spectral data acquisition.

[0117] c) Start the main control system 7 through the host computer 10, control the ND filter disc driving mechanism 92 to rotate the ND filter disc 611 to the position where the noise calibration disc is in the light path of the first beam of light, and the first beam of light transmits to the two-dimensional image sensor from the noise calibration disc after passing through the light splitting system, so that the two-dimensional image sensor acquires noise data.

[0118] d) Control the main filter disc driving mechanism 9 to rotate the main filter disc 6 to the first band-pass filter position, and control the ND filter disc driving mechanism 92 to rotate the ND filter disc 611 to the appropriate ND filter position, use the two-dimensional image sensor 3 to collect images, and subtract the noise data obtained in step b) to obtain a first band-pass filter data matrix D1.

[0119] e) Repeat steps c) and d), sequentially replace the first band-pass filter with a second band-pass filter and a third band-pass filter, and control the ND filter disc driving mechanism 92 to rotate the ND filter disc 611 to the appropriate ND filter position to obtain a second band-pass filter data matrix D2 and a third band-pass filter data matrix D3. The selection of appropriate ND filters according to environmental characteristics such as light intensity and measurement needs is a routine technique in the art, and the specific operation method of selecting appropriate ND filters is not described here.

[0120] f) Correct the obtained tristimulus values according to the correction coefficient matrix of embodiment 1.

[0121] g) Calculate the chrominance values of each pixel in the image and generate a chromatic image.

[0122] h) Output the chrominance values to the host computer 10 through the output module, convert them to , or color space values, and display or store the chromatic image.

[0123] The band-pass filters and noise calibration sheets of the present embodiment are arranged on the main filter disc 6 and the ND filter disc 611, respectively.

[0124] Embodiment 5

[0125] Compared with embodiments 1 and 4, the present embodiment further comprises a collimating lens and a second focusing lens. The collimating lens is arranged in the light path between the light splitting system 2 and the filter module, or in the light path between the imaging lens 1 and the light splitting system 2, for converting the light focused by the imaging lens into collimated light. The second focusing lens is arranged between the filter module and the two-dimensional image sensor 3, for refocusing the collimated light modulated by the filter module to the imaging surface of the two-dimensional image sensor 3.

[0126] The filter module can be the one described in embodiment 1, which only comprises the main filter disc 6, or the one described in embodiment 4, which comprises the main filter disc 6 and the ND filter disc 611.

[0127] When the imaging lens 1 is arranged in front of the light splitting system 2, it is possible that the distance between the imaging lens 1 and the two-dimensional image sensor 3 is greater than the back aperture of the imaging lens due to the structural size of the light filter module, resulting in unclear imaging. In particular, in the scheme shown in embodiment 4, the light filter module includes the main filter disc 6 and the ND filter disc 611, and the arrangement of multiple filter discs side by side further increases the distance between the imaging lens 1 and the two-dimensional image sensor 3. Therefore, the collimating lens and the second focusing lens are arranged to adjust the light to make the imaging clear.

[0128] Embodiment 6

[0129] Compared with embodiment 2, an ND filter disc 611 is arranged behind the main filter disc 6 in this embodiment, and different density ND filters are arranged on the ND filter disc 611, while the noise calibration disc is arranged on the ND filter disc 611 instead of the main filter disc 6. Compared with embodiment 4, the main filter disc 6 is replaced by four hole positions, respectively installing cieXr filter disc, cie Xb filter disc, cie Y filter disc and cie Z filter disc, and the device diagram is not drawn.

[0130] Embodiment 7

[0131] Compared with embodiment 6, the main filter disc 6 is replaced by three hole positions in this embodiment, respectively installing R filter disc, G filter disc and B filter disc, and the device diagram is not drawn.

[0132] Embodiment 8

[0133] As shown in Figure 5 , compared with embodiment 1, the spectral measurement device 5 is changed from the original light coupling into the optical fiber through the first focusing lens 4 and transmission to the fiber spectrometer to the light entering the spectral illuminometer 51 through the lens group (i.e. free space optical path mode), and the first focusing lens and the lens group are integrated in the spectral illuminometer 51. Other devices are the same as those in embodiment 1.

[0134] Embodiment 9

[0135] As shown in Figure 6 , compared with embodiment 1, the master control system 7 is cancelled in this embodiment, and all the logical control, data operation and maintenance and data processing are completed by the upper computer.

[0136] As embodiment 9 of the present application, the specific operation steps of using the imaging colorimetric measurement device to perform colorimetric test are as follows:

[0137] a) Place the object to be measured 11 at a certain distance in front of the imaging lens 1.

[0138] b) The light from the object 11 being measured is focused by the imaging lens 1 and then split into two beams by a beam splitting system. The first beam is used to transmit the light to the two-dimensional image sensor, and the second beam is used to transmit the light to the spectral measurement device for spectral data acquisition.

[0139] c) The host computer 10 controls the main filter disc drive mechanism 9 to rotate the main filter disc 6 to the noise calibration disc position, and uses the two-dimensional image sensor 3 to collect noise data.

[0140] d) Control the main filter optical disc drive mechanism 9 to rotate the main filter optical disc 6 to the position of the first bandpass filter, and use the two-dimensional image sensor 3 to acquire the image, and subtract the noise data obtained in step b) to obtain the first bandpass filter data matrix D1.

[0141] e) Repeat steps c) and d) to replace the first bandpass filter with the second and third bandpass filters in sequence, to obtain the second bandpass filter data matrix D2 and the third bandpass filter data matrix D3.

[0142] f) Obtained by correction based on the correction coefficient matrix Tristimulus values.

[0143] g) Calculate the chromaticity value of each pixel in the image and generate a chromaticized image.

[0144] h) Convert chroma values ​​to , or The values ​​of the color space, and how to display or store the colorized image.

[0145] Example 10

[0146] like Figure 7 As shown, compared with Embodiment 1, the main filter disc 6 is changed from a circular disc to a rectangular disc. The main filter disc 6 switches bandpass filters by translation. The main filter disc 6 is driven by two motors, namely the x-axis motor 131 and the y-axis motor 132. The noise calibration plate, the first bandpass filter, the second bandpass filter, and the third bandpass filter are installed in the holes of the main filter disc 6. By controlling the x-axis motor 131 and the y-axis motor 132, the selected bandpass filter is moved into the optical path of the first beam. The first beam passes through the selected bandpass filter and enters the two-dimensional image sensor 3. All other devices are the same as in Embodiment 1.

[0147] In various embodiments of the present application, different configurations and methods can be adjusted as needed to adapt to different measurement requirements and performance needs. The above embodiments can be considered as permutations and combinations of different technical solutions, combining different selections and optimized designs of optical filter discs, bandpass filters, spectral measurement devices, and other components. Specifically, embodiments 2 to 11 demonstrate more accurate colorimetric measurements and spectral data collection by replacing bandpass filter types, adding ND filters, modifying spectral measurement device configurations, adjusting optical filter disc driving methods, and other ways. These changes not only improve the accuracy of colorimetric measurements, but also provide flexible adaptability in different measurement environments.

Claims

1. An imaging colorimetric measurement method characterized by, The measurement method comprises the following steps: a) placing the object to be measured at a set distance in front of an imaging lens; b) focusing the light rays of the object to be measured by the imaging lens, passing through a light splitting system to divide the light rays into a first light beam and a second light beam, the first light beam being introduced into a two-dimensional image sensor, and the second light beam being introduced into a spectral measurement device and performing spectral distribution data acquisition; c) placing a noise calibration sheet in the light path of the first light beam to shield the light rays, thereby using the two-dimensional image sensor to acquire noise data, wherein the noise calibration sheet is made of pure black material with a reflectivity of less than 1%; d) the first light beam is introduced into the two-dimensional image sensor after passing through a first band-pass filter in the light splitting system, and the two-dimensional image sensor is used to acquire image data and subtract the noise data obtained in step c) to obtain a first band-pass filter data matrix D1; e) repeating steps c) and d) in turn replacing the first bandpass filter with a second bandpass filter, a third bandpass filter,..., an n-th bandpass filter to obtain a number of bandpass filtered data matrices, respectively a second bandpass filtered data matrix D2, a third bandpass filtered data matrix D3,..., an N-th bandpass filtered data matrix DN n where n is greater than or equal to 3; In steps c) to e), the first band-pass filter, the second band-pass filter, the third band-pass filter,..., and the nth band-pass filter are collectively referred to as band-pass filters, the noise calibration sheet and the band-pass filters are distributed on a filter disc of a filter module, and the noise calibration sheet and / or one of the band-pass filters are located in the light path of the first light beam by controlling the rotation or movement of the filter disc, so that the first light beam passes through one of the band-pass filters and / or the noise calibration sheet before being introduced into the two-dimensional image sensor; the filter disc is a main filter disc or includes a main filter disc and an ND filter disc, when the filter disc is the main filter disc, the noise calibration sheet is installed on the main filter disc; when the filter disc includes the main filter disc and the ND filter disc, the noise calibration sheet is installed on the ND filter disc, and the ND filter disc is closer to the two-dimensional image sensor relative to the main filter disc; f) converting and calibrating each band-pass filter data matrix to XYZ tristimulus values, denoted as X F , Y F , Z F , respectively, using the following formulas for calibration: [X F Y F Z F ] T = M C · [D1 D2 D3 … D n ] T wherein, Mc is a coefficient matrix corresponding to the initialization calibration of the n band-pass filters, to complete the initialization calibration; g) Coefficient correction of XYZ tristimulus values to X S , Y S , Z S (As follows) according to the spectral distribution data collected by the spectral measurement device in step b) to complete real-time calibration and calculate the chrominance value of each pixel in the image and generate a chromatic image; wherein, is the XYZ tristimulus value average value converted from the spectral data collected by the spectral measurement device through the chromaticity integral equation; the α, β, and γ calibration coefficient values are obtained through the above formula, and the XYZ tristimulus value of each pixel in the image is sequentially subjected to real-time calibration of the coefficients again by using the α, β, and γ calibration coefficient values. h) outputting the chrominance value through an output module and converting it into values of CIE XYZ, CIE xyY or CIE L*a*b* color space, displaying or storing the chrominance image.

2. An imaging colorimetry device, characterized by, The measurement device is used to implement the imaging chroma measurement method of claim 1, comprising an imaging lens, a light splitting system, a two-dimensional image sensor, a spectral measurement device and a filter module; the imaging lens is used to focus the light rays of the object to be measured and guide them into the light splitting system; the light splitting system divides the light rays of the object to be measured into a first light beam and a second light beam, the first light beam is introduced into the two-dimensional image sensor after passing through the filter module, and the second light beam is focused by a first focusing lens and introduced into the spectral measurement device; the filter module is installed with at least one noise calibration sheet and a plurality of band-pass filters for chroma measurement; the two-dimensional image sensor is used to receive the filtered light rays and convert them into digital images; The spectral measurement device is used for spectral measurement to obtain spectral data.

3. An imaging colorimetry device according to claim 2, wherein, The light splitting system is a semi-transparent and semi-reflective light splitting mirror or a semi-transparent and semi-reflective light splitting prism, which is used to divide the light rays converged by the imaging lens into the first light beam and the second light beam.

4. An imaging colorimetry device according to claim 2, wherein, The filter module comprises a main filter disc provided with a plurality of holes, at least one of which is provided with the noise calibration sheet, and the rest of which respectively correspond to the installation of a plurality of band-pass filters for colorimetric measurement. The noise calibration sheet is used to collect noise data before each color measurement, and the noise data is deducted from the subsequent measurement results to improve the measurement accuracy.

5. An imaging colorimetry device according to claim 2, wherein, The filter module comprises a main filter disc and an ND filter disc, each of which is provided with a plurality of holes, and each hole of the main filter disc is respectively provided with a band-pass filter for colorimetric measurement; one of the holes of the ND filter disc is provided with the noise calibration sheet, and each of the rest of the holes of the ND filter disc is respectively provided with an ND filter, and the optical densities of the plurality of ND filters are different; the noise calibration sheet is used to collect noise data before each color measurement, and the noise data is deducted from the subsequent measurement results to improve the measurement accuracy.

6. An imaging colorimetry device according to claim 2 or 5, characterized in that The collimating lens is arranged in the light path between the light splitting system and the filter module, or in the light path between the imaging lens and the light splitting system, and is used to convert the light rays introduced by the imaging lens into collimated light rays; the second focusing lens is arranged between the filter module and the two-dimensional image sensor, and is used to refocus the collimated light rays modulated by the filter module to the imaging surface of the two-dimensional image sensor.

7. An imaging colorimetry device according to claim 2, wherein, The main control system is used to control the cooperative work of each component, process the image and spectral data collected by the two-dimensional image sensor and the spectral measurement device, and output the final colorimetric analysis result and the colorized image; the main control system comprises a processor, a memory and an input / output interface; The processor is used to execute the preset program instructions, control the cooperative work of the imaging lens, the light splitting system, the filter module, the two-dimensional image sensor and the spectral measurement device, and process and analyze the collected digital image and spectral data; The memory is used to store program instructions and collected data; The input / output interface is used for communication with external devices; The data processing performed by the main control system includes: pre-processing the image collected by the two-dimensional image sensor, including bad pixel correction, dark current correction and gain correction; According to the type of the band-pass filter of the filter module, the image data of the corresponding color channel is extracted from the image collected by the two-dimensional image sensor; the spectral data collected by the spectral measurement device is corrected, including dark current correction, background noise correction and wavelength correction; according to the extracted image data and spectral data, the colorimetric value of each pixel in the image is calculated, and a colorized image is generated; the calculated colorimetric value is converted into a value in CIE XYZ, CIE xyY or CIE L*a*b* color space; according to the user's setting, the colorimetric analysis result and the colorized image are output and displayed or stored.

Images