Imaging chromaticity measuring method and measuring device based on same

Abstract

The invention relates to an imaging chromaticity measurement method and device. The measurement method comprises the following steps: a) placing an object to be measured in front of an imaging lens; b) the to-be-measured object light focused by the imaging lens is divided into two beams through a beam splitting system, and the first beam is guided into a two-dimensional image sensor; the second light beam is guided into spectral measurement equipment for spectral distribution data acquisition; c) the noise calibration sheet shields the first light beam, and the two-dimensional image sensor collects noise data; d) the first light beam passes through a first band-pass filter, a two-dimensional image sensor collects image data, and the noise data obtained in the step c) is deducted to obtain a first band-pass filtering data matrix; e) repeating the step d), and replacing the band-pass optical filter to obtain n band-pass optical filtering data matrixes; f) converting and calibrating each band-pass filtering data matrix into a # imgabs0 # tristimulus value; g) according to the spectral distribution data in the step b), carrying out real-time calibration on # imgabs1 # tristimulus values, calculating the chromatic value of the image and generating a chromaticized image; and h) outputting the chromatic value, and displaying or storing the chromaticized image.

Description

Technical Field

[0001] The present invention belongs to the field of color measurement technology, and in particular, relates to a method and a device for imaging chromaticity measurement and analysis by combining spectral analysis with filtering imaging technology. Background Art

[0002] With the continuous development of science and technology, people have put forward higher requirements for the accuracy and efficiency of color measurement. Traditional color measurement instruments are mainly divided into imaging colorimeters and spectral colorimeters, which have their own advantages and disadvantages, but have certain limitations in certain 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 The image is filtered by a color space matching filter and the brightness value and color information of each pixel in the image are analyzed to obtain the brightness and chromaticity distribution of the object surface.

[0004] The main advantage of imaging colorimeter is its fast measurement speed. It can simultaneously measure the brightness and chromaticity information of multiple points on the surface of an object, realize area array measurement, and quickly obtain information such as brightness / chromaticity uniformity on the surface of an object. It is suitable for online detection of mass production.

[0005] However, the measurement accuracy of imaging colorimeters is relatively low, and its accuracy is limited by the characteristics of the filter and the resolution of the image sensor. Especially when measuring objects with complex spectral reflectance characteristics, since the filter cannot completely match the spectral characteristics of these light sources or objects, it will cause large measurement errors. In addition, traditional imaging colorimeters usually cannot provide spectral information, which limits their application in color analysis and color matching. For example, in the field of LED lighting, measuring chromaticity coordinates alone cannot fully evaluate the spectral quality of LEDs, while spectral information is crucial for evaluating parameters such as color rendering and color temperature of LEDs.

[0006] Spectral colorimeter, also known as spectroradiometer, measures the radiation intensity of an object or light source at different wavelengths through spectral analysis technology to obtain spectral power distribution data. Then the tristimulus values ​​and chromaticity coordinates are calculated according to the CIE standard colorimetric observer function. Spectral colorimeter has higher measurement accuracy and more comprehensive spectral information, and can more accurately measure various light sources, including narrow spectrum light sources and objects with complex spectra. It can provide important color parameters such as spectral power distribution and color temperature (CCT).

[0007] However, spectral colorimeters can usually only perform point measurements or small area measurements, and cannot quickly obtain the overall brightness / chromaticity distribution of the object surface. This is inefficient in applications that require the detection of color uniformity on the surface of an object, such as quality inspection of monitors and TVs, and color and brightness distribution measurement of automotive interior lighting, and requires multiple scans and stitching 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, which uses multiple narrow-band filters or tunable filters to obtain images of objects at different wavelengths, and then reconstructs the spectrum to obtain the spectral information of the object. However, this method still has some problems, such as limited spectral resolution, complex data processing, and high cost. Although multispectral imaging technology combines the advantages of imaging and spectral technology to a certain extent, since multispectral imaging uses a limited number of narrow-band filters, its spectral resolution is limited by the number and bandwidth of 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 amount of data is large. The calculation of the spectral reconstruction algorithm is also relatively complex, which requires a lot of computing resources and time. Summary of the invention

[0009] In order to solve the above problems, the present invention proposes a new imaging colorimetric measurement device. The invention combines the high-efficiency array measurement capability of an imaging colorimeter with the high-precision spectrum measurement capability of a spectral colorimeter, overcoming the limitations of traditional color measurement technology.

[0010] The technical solution of the present invention includes: an imaging chromaticity measurement method, the measurement method comprising the following steps:

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

[0012] b) The light of the object to be measured focused by the imaging lens is divided into a first light beam and a second light beam through a light splitting system, the first light beam is introduced into a two-dimensional image sensor; the second light beam is introduced into a spectrum measurement device, and spectrum distribution data is collected;

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

[0014] d) The first light beam is introduced from the light splitting system through the first bandpass filter into the two-dimensional image sensor, and the two-dimensional image sensor is used to collect image data, and the noise data obtained in step c) is deducted to obtain the first bandpass filter data matrix D 1 ;

[0015] e) Repeating steps c) and d) or repeating step d), sequentially replacing the first bandpass filter with the second bandpass filter, the third bandpass filter, ..., the nth bandpass filter to obtain a plurality of bandpass filter data matrices, which are the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 , Nth bandpass filter data matrix D n , where n is greater than or equal to 3;

[0016] f) Convert and calibrate each bandpass filter data matrix into Three stimulus values ​​to complete initialization calibration;

[0017] g) according to the spectral distribution data collected by the spectral measurement device in step b), The three stimulus values ​​are coefficient corrected to complete real-time calibration, and the chromaticity value of each pixel in the image is calculated to generate a chromatic image;

[0018] h) Output the chromaticity value through the output module and convert it into , or Color space value, display or store chromaticity image.

[0019] In one embodiment, in steps c) to e), the first bandpass filter, the second bandpass filter, the third bandpass filter...the nth bandpass filter are collectively referred to as bandpass filters, the noise calibration plate and the bandpass filters are distributed on a filter disc of the filter module, and the noise calibration plate and / or the bandpass filter are located in the optical path of the first light beam by controlling the filter disc to rotate or move, so that the first light beam is introduced into the two-dimensional image sensor after passing through the bandpass filter and / or the noise calibration plate.

[0020] In one embodiment, in step f), each bandpass filter data matrix is ​​calibrated to Three stimulus values, this The three stimulus values ​​are recorded as , , , the calibration formula is as follows:

[0021]

[0022] in, , M c The coefficient matrix for initialization calibration corresponding to n bandpass filters.

[0023] In one embodiment, step g) recalibrates the spectrum distribution data collected by the spectrum measurement device. Three stimulus values, this The three stimulus values ​​are recorded as , , The formula is as follows:

[0024]

[0025] in, , , It is the average value of the three stimulus values ​​obtained by integrating the spectral data collected by the spectral measurement device through the chromaticity integral equation;

[0026] Through the above formula, we can get , , Calibration coefficient value, and use , , The calibration coefficient value is applied to each pixel in the image in turn. The three stimulus values ​​are recalibrated in real time.

[0027] The technical solution of the present invention also includes:

[0028] An imaging colorimetric measurement device, which is used to implement the above-mentioned imaging colorimetric measurement method, comprises: an imaging lens, a spectroscopic system, a two-dimensional image sensor, a spectrum measuring device and a filter module; the imaging lens is used to focus the light of the object to be measured and guide it into the spectroscopic system; the spectroscopic system divides 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 filter module, and the second light beam is focused by a first focusing lens and introduced into the spectrum measuring device; the filter module is equipped with at least one noise calibration plate 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 spectrum measuring device is used for spectrum measurement to obtain spectrum data.

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

[0030] In one embodiment, the filter module includes 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 chromaticity measurement; the noise calibration sheet is made of a pure black material with a reflectivity of less than 1%, and 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 filter module includes a main filter disc and an ND filter disc, wherein the main filter disc and the ND filter disc are respectively provided with a plurality of holes, and each of the holes of the main filter disc is respectively installed with a plurality of bandpass filters for chromaticity measurement; the noise calibration sheet is provided with the holes of the ND filter disc, and each of the remaining holes of the ND filter disc is respectively provided with an ND filter, and the optical density of the ND filters of one hole is different; the noise calibration sheet is made of a pure black material with a reflectivity of less than 1%, and 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.

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

[0033] In one embodiment, a main control system is further included, and the main control system is used to control the coordinated work of various components, process the images and spectral data collected by the two-dimensional image sensor and the spectral measurement device, and output the final colorimetric analysis results and the chromatic image; the main control system includes a processor, a memory and an input / output interface; the processor is used to execute preset program instructions, control the coordinated work of the imaging lens, the spectroscopic system, the filter module, the two-dimensional image sensor and the spectral measurement device, and process and analyze the collected digital image and the spectral data; the memory is used to store program instructions and collected data; the input / output interface is used to communicate with external devices; the data processing performed by the main control system includes:

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

[0035] b) extracting image data of corresponding color channels from the image collected by the two-dimensional image sensor according to the type of the bandpass filter of the filter 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 chromaticity value of each pixel in the image according to the extracted image data and the spectral data, and generating a chromaticity image;

[0038] e) Convert the calculated chromaticity value into , , or values ​​in other color spaces;

[0039] f) According to the user's settings, the chromaticity analysis results and chromaticity images are output and displayed or stored.

[0040] In one embodiment, the spectrum measurement device includes one of the following two implementations:

[0041] a) Fiber coupling method: a first focusing lens arranged at the rear end of the splitting system focuses the second light beam and guides it into the optical fiber; the optical fiber is used to transmit the light beam to the fiber spectrometer; the 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 spectroscopic system optically processes the second light beam so that it is incident on the spectrophotometer at a suitable angle and spot size; the spectrophotometer is used to perform spectral analysis on the light beam.

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

[0044] The present invention combines the area array measurement capability of an XYZ imaging colorimeter with the high-precision spectral measurement capability of a spectral colorimeter. The optical path is divided into two parallel data streams, namely an image sensor and a spectral measurement device, through a spectroscopic system. The present invention can simultaneously and rapidly obtain chromaticity distribution information and high-precision spectral information on the surface of an object, and realize real-time fusion of pixel-level chromaticity imaging and high-precision spectral correction. The limitations of traditional chromaticity measurement devices are overcome, the efficiency and accuracy of color measurement and analysis are improved, and real-time calibration of image sensor data is realized, overcoming the complex operation of previous imaging chromaticity measurement devices that require calibration upon startup.

[0045] The present invention creatively adds a noise calibration sheet to the filter module. The noise calibration sheet is made of pure black material with a reflectivity of less than 1%. By adding a noise calibration sheet to the filter module, the current noise can be measured before each measurement and the noise can be deducted. It can even be done that the noise calibration sheet is used to deduct the noise before each bandpass filter is used. This overcomes the previous noise calibration deduction that only needs to be performed on the colorimetric measurement device during calibration, greatly improves the timeliness of the noise data, and thus ensures the accuracy of the measurement data. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1Schematic diagram of an imaging colorimetry device according to Embodiment 1 of the present invention.

[0047] Figure 2 The present invention is a measurement flow chart of an imaging colorimetry device according to an embodiment of the present invention.

[0048] Figure 3 Schematic diagram of an imaging colorimetry device according to Embodiment 2 of the present invention.

[0049] Figure 4 Schematic diagram of an imaging colorimetry device according to Embodiment 4 of the present invention.

[0050] Figure 5 Schematic diagram of an imaging colorimetry device according to Embodiment 8 of the present invention.

[0051] Figure 6 Schematic diagram of an imaging colorimetry device according to Embodiment 9 of the present invention.

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

[0053] Among them: 1 imaging lens, 2 spectroscopic system, 3 two-dimensional image sensor, 4 first focusing lens, 5 spectrum measurement equipment, 51 spectrum illuminance meter, 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 drive mechanism, 92 ND filter disc drive mechanism, 10 host computer, 11 measured object, 131 x-axis motor, 132 y-axis motor. DETAILED DESCRIPTION

[0054] Example 1

[0055] The present embodiment discloses an imaging colorimetric measurement device, which is composed of an imaging lens 1, a spectroscopic system 2, a two-dimensional image sensor 3, a first focusing lens 4, a spectrum measurement device 51, a main filter disc 6, a main control system 7, an optical fiber 8, a main filter disc drive mechanism 9, and a host computer 10. The spectrum measurement device of the present embodiment is a fiber optic spectrometer 5. The light emitted (or reflected) by the object to be measured 11 is focused after passing through the imaging lens 1, and the focused light is incident on the spectroscopic system 2. In the present embodiment, the spectroscopic system 2 uses a semi-transparent and semi-reflective spectroscopic plane mirror, which divides the incident light into two beams: a first light beam and a second light beam. The light of the first light beam continues to propagate through the spectroscopic plane mirror and is incident on the main filter disc 6. A plurality of bandpass filters are installed on the main filter disc 6, which are the first bandpass filter, the second bandpass filter, and the third bandpass filter. In addition, a noise calibration sheet is also installed on the main filter disc 6. The first bandpass filter in this embodiment is a cieX filter, the second bandpass filter is a cieY filter, and the third bandpass filter is a cieZ filter. In other embodiments, the bandpass filters may also be the R, G, and B filters described in Example 3. The noise calibration sheet is a lens made of pure black material with a reflectivity of less than 1%, which is close to a full black lens. In this embodiment, the noise calibration sheet uses a carbon nano ultra-black coating with a reflectivity of less than 0.2%; the signal collected by the two-dimensional image sensor 3 is used as noise and is eliminated in subsequent measurement results, thereby improving the accuracy of detection. The main filter disc drive mechanism 9 controls the rotation of the main filter disc 6, selects different bandpass filters or noise calibration plates, and after passing through the selected bandpass filters, the light finally reaches the two-dimensional image sensor 3. The two-dimensional image sensor 3 in this embodiment is a black and white sensor, and it can also be a color sensor in other embodiments. The two-dimensional image sensor 3 converts the received light signal into an electrical signal to form a digital image. After the second light beam is reflected by the spectroscope, it is incident on the first focusing lens 4. The function of the first focusing lens 4 is to focus the second light beam and couple it efficiently into the optical fiber 8. The optical fiber 8 transmits the light to the spectrum measurement device 5. In this embodiment, the spectrum 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 each component, including controlling the rotation of the main filter disc 6, controlling and collecting spectral data of the two-dimensional image sensor 3 and the spectrum measurement device 5, and processing and analyzing the collected digital image and spectrum data. The host computer 10 is used to display the measurement results, set measurement parameters, etc.

[0056] The main control system 7 includes a processor, a memory and an input / output interface; the processor is used to execute preset program instructions, control the coordinated work of the imaging lens 1, the spectroscopic system 2, the filter module, the two-dimensional image sensor 3 and the spectrum measurement device 5, and process and analyze the collected digital image data and spectrum 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 main control system 7 includes:

[0058] a) Image preprocessing: Preprocess the original image collected by the two-dimensional image sensor to improve the image quality. The preprocessing steps include: ① Bad pixel correction: Detect and repair bad pixels in the image (such as pixels with abnormal brightness). ② Dark current correction: Deduct the dark current signal generated by the sensor itself. ③ Gain correction: Adjust the gain of the image to compensate for the unevenness of the sensor sensitivity. ④ Imaging lens shading correction: Compensate for the image edge brightness attenuation caused by the imaging lens.

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

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

[0061] d) Chromaticity value calculation and image generation: Based on the extracted image data (X, Y, Z) and spectral data, the chromaticity value of each pixel in the image is calculated and a chromatic image is generated. The spectral data of the spectral measurement device 5 is used to calculate Tristimulus values.

[0062] e) Color space conversion: Convert the calculated chromaticity values ​​into different color spaces to meet different application requirements. Commonly used color spaces include , , .

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

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

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

[0066] b) The light of the object 11 to be measured is focused by the imaging lens 1 and is divided into two light beams after passing through a light splitting system. The first light beam is used to be transmitted to the two-dimensional image sensor, and the second light beam is used to be transmitted to the spectrum measurement device 5 for spectrum data collection.

[0067] c) The first light beam is directed from the spectroscopic system through a noise calibration sheet into a two-dimensional image sensor, thereby using the two-dimensional image sensor to collect noise data.

[0068] d) The first light beam is transmitted from the light splitting system through the first bandpass filter to the two-dimensional image sensor, and the two-dimensional image sensor collects image data and deducts the noise data obtained in step b) to obtain a first bandpass filter data matrix D 1 .

[0069] e) Repeat steps c) and d), replace the first bandpass filter with the second bandpass filter and the third bandpass filter in turn, and obtain the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 .

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

[0071] f) The first bandpass filter data matrix D 1 , the second bandpass filter data matrix D 2 and the third bandpass filter data matrix D 3 Convert and calibrate to Three stimulus values; The three stimulus values ​​are recorded as , , , the calibration formula is as follows:

[0072]

[0073] in, , M cThe coefficient matrix for initialization calibration corresponding to the three bandpass filters.

[0074] g) according to the spectral distribution data collected by the spectral measurement device 5 in step b), The three stimulus values ​​are calibrated in real time. The three stimulus values ​​are recorded as , , , and calculate the chromaticity value of each pixel in the image and generate a chromatic image. The formula for tristimulus values ​​is as follows:

[0075]

[0076] in, , , It is the average value of the three stimulus values ​​calculated by using a spectral measurement device to collect spectral data of the measurement area;

[0077] Through the above formula, we can get , , Calibration coefficient value, and use , , The calibration coefficient value is applied to each pixel in the image in turn. The three stimulus values ​​are used for real-time calibration of coefficients.

[0078] h) Output the chromaticity value through the output module and convert it into , or Color space values, and display or store chromaticity images.

[0079] In step c) to step e), since the noise calibration plate, the first bandpass filter, the second bandpass filter and the third bandpass filter of this embodiment are annularly distributed on the main filter plate 6 of the filter module, the main filter plate 6 is controlled to rotate so that one of the noise calibration plate, the first bandpass filter, the second bandpass filter and the third bandpass filter is located in the optical path of the first light beam, so that the first light beam passes through one of the noise calibration plate, the first bandpass filter, the second bandpass filter and the third bandpass filter and is transmitted to the two-dimensional image sensor, so that the two-dimensional image sensor can collect two-dimensional imaging data of the light passing through the corresponding bandpass filter or the noise calibration plate.

[0080] The noise calibration sheet uses a carbon nano ultra-black coating and is made of pure black material with a reflectivity of less than 0.2%, which is close to a full black lens. The noise calibration sheet can perform a noise detection before a single measurement and eliminate it in the measurement results of all subsequent bandpass filters, thereby improving the accuracy of the detection. It is also possible to repeat steps c) and d) in sequence to switch to the noise calibration sheet before switching the bandpass filter each time, so that before each bandpass filter is filtered, the noise calibration sheet will be used for denoising first, which greatly improves the timeliness of the noise data and thus ensures the accuracy of the measurement data.

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

[0082] The main control system 7 of this embodiment is connected to the host computer 10, and 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 Color space values, and display or store chromaticity images.

[0083] Example 2

[0084] like Figure 3 As shown, compared with Example 1, the main filter disc 6 of this embodiment is replaced with a five-hole main filter disc 601, and the five-hole main filter disc 601 has five holes, and a cie Xr filter, a cie Xb filter, a cie Y filter, a cie Z filter and a noise calibration plate are installed in each hole in sequence. Other devices are the same as those in Example 1.

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

[0086] Because the bandpass filter combination of the present embodiment is changed from cie X, cie Y, cie Z filters to cie Xr, cie Xb, cie Y, cie Z filters, four bandpass filter data matrices are obtained, namely, the first bandpass filter data matrix D 1 , the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 and the fourth bandpass filter data matrix D 4 , the four bandpass filter data matrices are converted and calibrated into Three stimulus values, this The three stimulus values ​​are recorded as , , , the calibration formula is as follows:

[0087]

[0088] in, , M c The coefficient matrix for initialization calibration corresponding to the 4 bandpass filters.

[0089] As Embodiment 2 of the present invention, the specific operation steps of using the imaging colorimetric measurement device to perform colorimetric measurement are as follows:

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

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

[0092] c) The host computer 10 starts the main control system 7, controls the main filter disk drive mechanism 9 to rotate the main filter disk 6 to the position of the noise calibration plate, and the first light beam is transmitted from the spectroscopic system through a noise calibration plate to the two-dimensional image sensor, so that the two-dimensional image sensor collects noise data.

[0093] d) Control the main filter disc drive mechanism 9 to rotate the main filter disc 6 to the first bandpass filter position, and use the two-dimensional image sensor 3 to collect images, and deduct the noise data obtained in step b) to obtain the first bandpass filter data matrix D 1 .

[0094] e) Repeat steps c) and d), replace the first bandpass filter with the second bandpass filter, the third bandpass filter and the fourth bandpass filter in sequence, and obtain a second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3, the fourth bandpass filter data matrix D 4 .

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

[0096] f) Corrected by the correction coefficient matrix Tristimulus values.

[0097] g) Calculate the chromaticity value of each pixel in the image and generate a chromatic image.

[0098] h) Output the chromaticity value to the host computer 10 through the output module and convert it into , or Color space values, and display or store chromaticity images.

[0099] Example 3

[0100] Compared with Example 1, in this embodiment, the four holes of the main filter disc 6 are respectively installed with an R filter, a G filter, a B filter and a noise calibration plate, and other devices are the same as those in Example 1, and the device diagram is not drawn.

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

[0102] As Embodiment 3 of the present invention, the specific operation steps of using the imaging colorimetry device to perform colorimetry are as follows:

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

[0104] b) The light beam focused by the imaging lens 1 on the object to be measured 11 is divided into two light beams after passing through a light splitting system, the first light beam is used to be transmitted to the two-dimensional image sensor, and the second light beam is used to be transmitted to the spectrum measurement device 5 for spectrum data collection;

[0105] c) starting the main control system 7 through the host computer 10, controlling the main filter disk driving mechanism 9 to rotate the main filter disk 6 until the noise calibration plate is in the optical path of the first light beam, and the first light beam is transmitted from the spectroscopic system through the noise calibration plate to the two-dimensional image sensor, so that the two-dimensional image sensor collects noise data;

[0106] d) Control the main filter disc drive mechanism 9 to rotate the main filter disc 6 to the first bandpass filter position, and use the two-dimensional image sensor 3 to collect images, and deduct the noise data obtained in step c) to obtain the first bandpass filter data matrix D1 .

[0107] e) Repeat steps c) and d), replace the first bandpass filter with the second bandpass filter and the third bandpass filter in turn, and obtain the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 . .

[0108] f) Corrected by the correction coefficient matrix Tristimulus values.

[0109] g) Calculate the chromaticity value of each pixel in the image and generate a chromatic image.

[0110] h) Output the chromaticity value to the host computer 10 through the output module and convert it into , or Color space values, and display or store chromaticity images.

[0111] Example 4

[0112] like Figure 4 As shown, the present embodiment is different from the embodiment 1 in that an ND filter disc 611 is placed behind the main filter disc 6, and ND filters of different optical densities are arranged on the ND filter disc 611, and no noise calibration sheet is arranged on the main filter disc 6, and the noise calibration sheet is placed on the ND filter disc 611. The main filter disc 6 and the ND filter disc 611 of the present embodiment together constitute a filter module.

[0113] Compared with Example 1, ND filters with different optical densities can be provided to select different ND filters according to the light intensity of the object to be measured, thereby adjusting the light intensity entering the two-dimensional image sensor 3, so as to measure more precise (X, Y, Z) brightness, and thus measure more accurate chromaticity.

[0114] As Embodiment 4 of the present invention, the specific operation steps of using the imaging colorimetric measurement device to perform colorimetric measurement are as follows:

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

[0116] b) The light of the object 11 to be measured is focused by the imaging lens 1 and is divided into two light beams after passing through a light splitting system. The first light beam is used to be transmitted to the two-dimensional image sensor, and the second light beam is used to be transmitted to the spectrum measurement device 5 for spectrum data collection.

[0117] c) The host computer 10 starts the main control system 7, controls the ND filter disk driving mechanism 92 to rotate the ND filter disk 611 until the noise calibration plate is in the optical path of the first light beam, and the first light beam is transmitted from the spectroscopic system through the noise calibration plate to the two-dimensional image sensor, so that the two-dimensional image sensor collects noise data.

[0118] d) controlling the main filter disc drive mechanism 9 to rotate the main filter disc 6 to the first bandpass filter position, and controlling the ND filter disc drive mechanism 92 to rotate the ND filter disc 611 to a suitable ND filter position, using the two-dimensional image sensor 3 to capture an image, and deducting the noise data obtained in step b) to obtain a first bandpass filter data matrix D 1 .

[0119] e) Repeat steps c) and d), replace the first bandpass filter with the second bandpass filter and the third bandpass filter in sequence, and control the ND filter disc driving mechanism 92 to rotate the ND filter disc 611 to a suitable ND filter position, and obtain the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 Among them, selecting a suitable ND filter according to environmental characteristics such as light intensity and measurement needs is a conventional technology in the art, and the specific operation method of selecting a suitable ND filter is not repeated here.

[0120] f) Correction according to the correction coefficient matrix of Example 1 to obtain Tristimulus values.

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

[0122] h) Output the chromaticity value to the host computer 10 through the output module and convert it into , or Color space values, and display or store chromaticity images.

[0123] The bandpass filter and the noise calibration plate of this embodiment are respectively arranged on the main filter plate 6 and the ND filter plate 611.

[0124] Example 5

[0125] Compared with Embodiment 1 and Embodiment 4, this embodiment further includes a collimating lens and a second focusing lens. The collimating lens is arranged in the optical path between the spectroscopic system 2 and the filter module, or in the optical path between the imaging lens 1 and the spectroscopic system 2, and is used to convert 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, and is used to refocus the collimated light modulated by the filter module onto the imaging surface of the two-dimensional image sensor 3.

[0126] The filter module may be the one including only the main filter disc 6 as described in the first embodiment, or may be the one including the main filter disc 6 and the ND filter disc 611 as described in the fourth embodiment.

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

[0128] Example 6

[0129] Compared with Example 2, in this embodiment, an ND filter disc 611 is placed behind the main filter disc 6, and ND filters of different optical densities are arranged on the ND filter disc 611. Meanwhile, the main filter disc 6 is not provided with a noise calibration sheet, and the noise calibration sheet is placed on the ND filter disc 611. Compared with Example 4, in this embodiment, the main filter disc 6 is replaced with four holes, and the cieXr filter, cieXb filter, cieY filter, and cieZ filter are installed respectively, and the device diagram is not drawn.

[0130] Example 7

[0131] Compared with Example 6, in this embodiment, the main filter disc 6 is replaced with three holes, and the R filter, the G filter, and the B filter are installed respectively, and the device diagram is not drawn.

[0132] Example 8

[0133] like Figure 5 As shown, compared with Example 1, the spectrum measuring device 5 of this embodiment is changed from coupling the light into the optical fiber through the first focusing lens 4 and transmitting it to the optical fiber spectrometer to entering the spectrum illuminance meter 51 through a lens group (i.e., a free space optical path mode), and the spectrum illuminance meter 51 is integrated with the first focusing lens and the lens group. Other devices are the same as those in Example 1.

[0134] Example 9

[0135] like Figure 6 As shown, compared with Example 1, this embodiment cancels the main control system 7, and all logic control, data operation and maintenance, and data processing are completed by the host computer.

[0136] As Embodiment 9 of the present invention, the specific operation steps of using the imaging colorimetric measurement device to perform colorimetric testing are as follows:

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

[0138] b) The imaging lens 1 gathers the light of the object to be measured 11 and divides it into two light beams after passing through a light splitting system. The first light beam is used to transmit to the two-dimensional image sensor, and the second light beam is used to transmit to the spectrum measurement equipment for spectrum data collection.

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

[0140] d) Control the main filter disc drive mechanism 9 to rotate the main filter disc 6 to the first bandpass filter position, and use the two-dimensional image sensor 3 to collect images, and deduct the noise data obtained in step b) to obtain the first bandpass filter data matrix D 1 .

[0141] e) Repeat steps c) and d), replace the first bandpass filter with the second bandpass filter and the third bandpass filter in turn, and obtain the second bandpass filter data matrix D 2 , the third bandpass filter data matrix D 3 .

[0142] f) Corrected by the correction coefficient matrix Tristimulus values.

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

[0144] h) Convert the chromaticity value to , or Color space values, and display or store chromaticity images.

[0145] Example 10

[0146] like Figure 7 As shown, compared with Example 1, the main filter disc 6 of this embodiment is changed from a circular disc to a rectangular disc, the main filter disc 6 switches the bandpass filter by translation, the main filter disc 6 is driven by two motors, the two motors are an x-axis motor 131 and a y-axis motor 132, the noise calibration disc, the first bandpass filter, the second bandpass filter and the third bandpass filter are installed in the hole of the main filter disc 6, the selected bandpass filter is moved into the optical path of the first light beam by controlling the x-axis motor 131 and the y-axis motor 132, and the first light beam passes through the selected bandpass filter and enters the two-dimensional image sensor 3. Other devices are the same as those of Example 1.

[0147] In multiple embodiments of the present invention, different configurations and methods can be adjusted as needed to adapt to different measurement requirements and performance requirements. The above embodiments can be regarded as a combination of different technical solutions, combining different selections and optimized designs of multiple components such as filter discs, bandpass filters, and spectral measurement equipment. Specifically, Examples 2 to 11 show how to achieve more accurate colorimetric measurement and spectral data acquisition by changing the type of bandpass filters, adding ND filters, modifying the configuration of spectral measurement equipment, and adjusting the filter disc drive mode. These changes not only improve the accuracy of colorimetric measurement, but also provide flexible adaptability in different measurement environments.

Claims

1. An imaging chromaticity measurement method, characterized in that: The measurement method includes the following steps: a) Place the object to be measured at a set distance in front of the imaging lens; b) The light of the object to be measured focused by the imaging lens is divided into a first light beam and a second light beam through a light splitting system, the first light beam is introduced into a two-dimensional image sensor; the second light beam is introduced into a spectrum measurement device, and spectrum distribution data is collected; c) placing a noise calibration sheet in the optical path of the first light beam to block the light, thereby collecting noise data using a two-dimensional image sensor; d) the first light beam is introduced from the light splitting system to the two-dimensional image sensor after passing through the first bandpass filter, the two-dimensional image sensor is used to collect image data, and the noise data obtained in step c) is deducted to obtain a first bandpass filter data matrix D1; e) Repeating steps c) and d) or repeating step d), replacing the first bandpass filter with the second bandpass filter, the third bandpass filter, ..., the nth bandpass filter in sequence to obtain a plurality of bandpass filter data matrices, namely the second bandpass filter data matrix D2, the third bandpass filter data matrix D3, ..., the Nth bandpass filter data matrix D n , where n is greater than or equal to 3; f) Convert and calibrate each bandpass filter data matrix into Three stimulus values ​​to complete initialization calibration; g) according to the spectral distribution data collected by the spectral measurement device in step b), The three stimulus values ​​are coefficient corrected to complete real-time calibration, and the chromaticity value of each pixel in the image is calculated to generate a chromatic image; h) Output the chromaticity value through the output module and convert it into , or Color space value, display or store chromaticity image.

2. The imaging colorimetric measurement method according to claim 1, characterized in that: In steps c) to e), the first bandpass filter, the second bandpass filter, the third bandpass filter, ..., the nth bandpass filter are collectively referred to as bandpass filters, and the noise calibration plate and the bandpass filters are distributed on a filter disc of the filter module. The noise calibration plate and / or one of the bandpass filters are located in the optical path of the first light beam by controlling the filter disc to rotate or move, so that the first light beam is introduced into the two-dimensional image sensor after passing through one of the bandpass filters and / or the noise calibration plate.

3. The imaging colorimetry method according to claim 1, characterized in that: In step f), each bandpass filter data matrix is ​​calibrated to Three stimulus values, this The three stimulus values ​​are recorded as , , , the calibration formula is as follows: in, , M c The coefficient matrix for initialization calibration corresponding to n bandpass filters.

4. The imaging colorimetric measurement method according to claim 1, characterized in that: Step g) recalibrates the spectrum distribution data collected by the spectrum measurement device Three stimulus values, this The three stimulus values ​​are recorded as , , The formula is as follows: in, , , It is obtained by converting the spectrum data collected by the spectrum measurement device through the chromaticity integral equation The average of the three stimulus values; Through the above formula, we can get , , Calibration coefficient value, and use , , The calibration coefficient value is applied to each pixel in the image in turn. The three stimulus values ​​are calibrated again in real time.

5. An imaging colorimetric measuring device, characterized in that: The measuring device is used to implement an imaging colorimetry method as described in any one of claims 1 to 4, comprising: an imaging lens, a spectroscopic system, a two-dimensional image sensor, a spectrum measuring device and a filter module; the imaging lens is used to focus the light of the object to be measured and guide it into the spectroscopic system; the spectroscopic system divides 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 filter module, and the second light beam is focused by a first focusing lens and introduced into the spectrum measuring device; the filter module is installed with at least one noise calibration plate and a plurality of bandpass filters for colorimetry; the two-dimensional image sensor is used to receive the filtered light and convert it into a digital image; the spectrum measuring device is used for spectrum measurement to obtain spectrum data.

6. The imaging colorimetric measuring device according to claim 5, characterized in that: The light splitting system is a semi-transparent and semi-reflective light splitting plane mirror, or a semi-transparent and semi-reflective light splitting prism, which is used to split the light converged by the imaging lens into the first light beam and the second light beam.

7. The imaging colorimetric measuring device according to claim 5, characterized in that: The filter 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 plate, 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 of less than 1%, and is used to collect noise data before each color measurement, and to deduct the noise data from subsequent measurement results to improve measurement accuracy.

8. The imaging colorimetric measuring device according to claim 5, characterized in that: The filter module includes a main filter disc and an ND filter disc, wherein the main filter disc and the ND filter disc are respectively provided with a plurality of holes, and each of the holes of the main filter disc is respectively installed with a plurality of bandpass filters for chromaticity measurement; the noise calibration sheet is arranged in one of the holes of the ND filter disc, and each of the remaining 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 made of a pure black material with a reflectivity of less than 1%, and 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.

9. An imaging colorimetric measuring device according to claim 5 or 8, characterized in that: It also includes a collimating lens and a second focusing lens; the collimating lens is arranged in the optical path between the spectroscopic system and the filter module, or in the optical path between the imaging lens and the spectroscopic system, and is used to convert the light introduced by the imaging lens into collimated light; the second focusing lens is arranged between the filter module and the two-dimensional image sensor, and is used to refocus the collimated light modulated by the filter module onto the imaging surface of the two-dimensional image sensor.

10. The imaging colorimetric measuring device according to claim 5, characterized in that: It also includes a main control system, which is used to control the coordinated work of various 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 results and the chromatic image; the main control system includes a processor, a memory, and an input / output interface; The processor is used to execute preset program instructions, control the coordinated work of the imaging lens, the spectroscopic system, the filter module, the two-dimensional image sensor and the spectrum measurement device, and process and analyze the collected digital image and the spectrum data; the memory is used to store program instructions and collected data; The input / output interface is used to communicate with external devices; The data processing performed by the main control system includes: a) preprocessing the image captured by the two-dimensional image sensor, including bad pixel correction, dark current correction and gain correction, etc.; b) extracting image data of corresponding color channels from the image collected by the two-dimensional image sensor according to the type of the bandpass filter of the filter module; c) correcting the spectral data collected by the spectral measurement device, including dark current correction, background noise correction and wavelength correction, etc.; d) calculating the chromaticity value of each pixel in the image according to the extracted image data and the spectral data, and generating a chromaticity image; e) Convert the calculated chromaticity value into , , or values ​​in other color spaces; f) According to the user's settings, the chromaticity analysis results and chromaticity images are output and displayed or stored.

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