CN117824837A - Water-soluble luminous paint performance detection method and system - Google Patents
Water-soluble luminous paint performance detection method and system Download PDFInfo
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Abstract
The invention relates to the technical field of paint color difference detection, in particular to a method and a system for detecting the performance of water-soluble luminous paint, which comprise the steps of taking at least one water-soluble luminous paint to be detected and a standard paint as detection samples, respectively pouring different detection samples into different partitions of a tray, and waiting for the detection samples to be stationary, wherein the heights of the detection samples reach calibrated scales; and when the tray is irradiated by parallel light, acquiring an image of the detection sample through the camera, obtaining a pixel color value mean space curve of the detection sample transformed along with the observation angle, and calculating the French distance between the color value mean space curves of different partitions to judge whether the color difference meets the requirement. The invention solves the problem that the color of the water-soluble luminous coating material is difficult to compare with the color difference along with the observation angle, and simultaneously simplifies the difficulty of color difference identification by utilizing the image processing technology, and reduces the cost of purchasing color difference instruments for color difference identification.
Description
Technical Field
The invention relates to the technical field of paint color difference detection, in particular to a method and a system for detecting the performance of a water-soluble luminous paint.
Background
The luminous paint is a self-luminous material capable of absorbing and storing light energy after light irradiation, has the advantages of zero energy consumption and zero carbon emission, and is applied to tunnel walls, pavement markings, indication marks of special road sections of roads such as curves and the like. The color of the luminous paint is the same as that of a common paint, and whether the color has chromatic aberration is also required to be detected, but the detection difficulty of the luminous paint is that the color of the luminous paint can change along with different light sources, lighting conditions and observation angles, so that proper light sources, lighting conditions, and correct observation angles and measurement modes are required to be selected for accurate color measurement. Secondly, the fluorescence intensity and fluorescence lifetime of the luminescent coating material are also affected by various factors, such as temperature, humidity, ultraviolet radiation, etc., which require that these influencing factors be controlled during the measurement of the luminescent material, thereby ensuring the accuracy and repeatability of the measurement result. The color difference detecting instrument of the luminous paint with comparatively specialty is an instrument such as a fluorescence spectrophotometer or a fluorescence microscope, but the cost for purchasing the specialized color difference detecting instrument is very long and short, so the cost is high.
Disclosure of Invention
The invention aims to provide a method and a system for detecting the performance of a water-soluble luminous paint, which are used for solving the problems that the water-soluble luminous paint has color change at a plurality of observation angles and is difficult to compare chromatic aberration, and meanwhile, the difficulty of simplifying chromatic aberration identification by utilizing an image processing technology is solved.
In order to achieve the above purpose, in one aspect, the invention provides a method for detecting performance of water-soluble luminous paint, which is applied to a device for detecting performance of water-soluble luminous paint, the device comprises a tray for containing water-soluble luminous paint, a vertical column is arranged in the center of the tray, a camera is arranged at the top end of the vertical column, the tray is provided with at least two independent partitions, partition plates are used for separation, and the partition plates are perpendicular and meet the vertical column; the method comprises the following steps:
taking at least one water-soluble luminous paint and standard paint to be detected as detection samples, respectively pouring different detection samples into different partitions of a tray, and waiting for the detection samples to be stationary when the heights of the detection samples reach the calibrated scales; acquiring the position of the baffle plate and the area for detecting the sample through the camera, drawing a ray path by taking the center of intersection of the baffle plate as a circular point, and reading pixel color values on the ray path;
sequentially taking pixel color values on the same ray path as discrete points according to an observation angle to be arranged in a coordinate axis, and using maximum likelihood estimation to fit a mapping curve for obtaining the pixel color values and the observation angle to be recorded as a color value space curve; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
and (3) shifting and overlapping the color value mean value space curves of different partitions on an observation angle axis, and calculating the Frechet distance between the color value mean value space curves of different partitions, wherein when the Frechet distance respectively corresponding to the water-soluble noctilucent paint to be detected and the standard paint exceeds a set distance threshold, the color difference does not meet the requirement.
Further, the method for acquiring the position of the baffle and the area for detecting the sample through the camera, drawing a ray path by taking the center of intersection of the baffles as a round point and reading pixel color values on the ray path comprises the following steps:
when the tray is irradiated by parallel light, an image of a detection sample is acquired through a camera and is recorded as a first image, the first image is corrected for a visual angle, an area of the detection sample on the first image is searched for and is recorded as a second image, the position of a baffle plate is detected on the second image, and areas corresponding to the detection samples in different areas are marked on the second image according to the position of the baffle plate; and searching the center of the intersection of the partition plates on the second image to serve as a circle center, drawing a ray path on the second image by taking the circle center as an endpoint, enabling the area corresponding to the detection sample in the same partition to pass through at least two ray paths, and reading pixel color values on the ray paths.
Further, the method for correcting the viewing angle of the first image and searching the area of the detection sample on the first image is recorded as a second image, and comprises the following steps:
passing the first image through a perspective transformation matrixTransforming to obtain standard image, perspective transformation matrixThe method comprises the following steps:；
wherein the method comprises the steps of、、Andis a transformation parameter that is used to transform the data,andis the coordinates of the center point of the image; detecting edges of the standard image through a Canny algorithm to obtain the edge position of the tray, and obtaining an area surrounded by the edge position of the tray through the edge position of the tray to serve as an area of a detection sample on the first image;
the acquisition mode of the transformation parameters comprises marking anchor points of four non-collinear anchoring positions on the edge position of the tray before the performance detection of the water-soluble luminous paint, respectively shooting the tray image from the position of a camera installed on a vertical upright post and the position right above the tray as a first view and a second view, respectively marking the sitting mark of the anchor point on the first view asThe coordinates of the anchor point on the second view are recorded asWhereinIs the firstAnchor points; four groups of functions are constructed through the coordinates of the same anchor point in the first view and the second view, wherein the four groups of functions are as follows:
and；
Wherein the method comprises the steps of=1, 2, 3 and 4,andis the coordinates of the center point of the image; obtaining transformation parameters through the four groups of functions、、And。
further, the method for drawing the ray paths on the second image by taking the circle center as an endpoint, enabling the region corresponding to the detection sample in the same partition to pass through at least two ray paths, and reading the pixel color values on the ray paths further comprises:
drawing ray paths towards the edge position of the tray by taking the circle center as an endpoint, reading RGB values of pixel grids of the ray paths from the circle center to the edge position of the tray, and drawing at least two ray paths by the same partition according to partition positions and equal division angles; the RGB values of the pixel grid are sequentially converted into Lab values as pixel color values.
Further, the method for sequentially converting the RGB values of the pixel grid into Lab values as pixel color values comprises the following steps: RGB values are changed from original [0,255 ]]Normalized to [0,1 ]]Obtaining、Andwill be、Andconversion to linear RGB by a first conversion formula、Andwherein the first conversion formula is:
；
will beConversion intoThe formula of (2) applies equally toAndrespectively transformed to obtainAnd；
will be、Andrespectively converting into normalized XYZ values through a second conversion formula, wherein the second conversion formula is as follows:；
normalized XYZ value、Andwherein，，Will be、Andthrough a third conversion formulaNonlinear conversion correction is carried out to obtain、Andwherein the third conversion formula is:；
will beConversion intoThe formula of (2) applies equally toAndrespectively transformed to obtainAnd；
will be、Andconverting to obtain pixel color value, lab value, wherein，，。
Further, the method for fitting a mapping curve for obtaining pixel color values and observation angles by using maximum likelihood estimation further comprises the following steps:
sequentially adjusting Lab values according to the observation anglesSequentially as discrete points arranged in a coordinate axis, each observation angleWith a corresponding set of、Andthe value is recorded asThe method comprises the steps of carrying out a first treatment on the surface of the The saidMeets the normal distribution of multiple elementsLikelihood function of mapping curveThe method comprises the following steps:；
wherein the method comprises the steps ofWhileRespectively representing model parameters of theta, N is the sampling number of LAB values,to obtain the variance of the Lab value, the model parameters are obtained by taking the derivative of the likelihood function by gradient descent method and when the derivative is 0Obtaining a mapping curve as by model parametersWhereinRepresenting any one of L, a and b values.
Further, the method for shifting and overlapping the plurality of color value space curves of the same partition on the observation angle axis comprises the following steps: taking one of the color value space curves as a first curve and equally taking the first curveThe set of points isThe other color value space curve which is shifted and overlapped at the same time is marked as a second curve and m point sets are equidistantly takenThe method comprises the steps of carrying out a first treatment on the surface of the By moving vectorsMoving the second curve to the first curve, the sum of squared Euclidean distances of the first curve and the second curveThe method comprises the following steps:；
the coordinate data of the point set is input to obtain、、Andunder the condition thatThereby shifting and overlapping the second curve to the first curve.
Further, the equidistant ones are takenThe method for the point set comprises the following steps:
taking the observation angle from the first curveThe minimum time is taken as the first pointTaking the same observation angle on the second curveAs the first pointFrom the first point along the viewing angleEquidistant selection of the direction of increase leavesA set of points; the angle of observationThe first point at maximum corresponds to a point on the first curve or the second curve at the tray edge position.
Further, the method for setting the distance threshold value comprises the following steps: and respectively setting distance thresholds under different observation angles, wherein the distance thresholds are set according to the color difference recognition sensitivity of human eyes under different observation angles.
Based on the same inventive concept, on the other hand, the invention also provides a water-soluble luminous coating performance detection system which is applied to a water-soluble luminous coating performance detection device, wherein the detection device comprises a tray, a vertical column is arranged in the center of the tray, a camera is arranged at the top end of the vertical column, the tray is provided with at least two independent partitions, the partitions are separated by using a partition plate, and the partition plate is vertical and is intersected with the vertical column; the tray is used for accommodating detection samples, the detection samples comprise at least one water-soluble luminous paint and standard paint to be detected, different subareas are used for accommodating different detection samples, and calibrated scales are arranged in the subareas for verifying that the detection samples reach the height; the system comprises:
the image acquisition module is used for acquiring the position of the partition board and the area for detecting the sample through the camera, drawing a ray path by taking the center of intersection of the partition boards as a round point and reading pixel color values on the ray path;
the color difference curve module is used for sequentially arranging pixel color values on the same ray path as discrete points in a coordinate axis according to an observation angle, and mapping curves of the pixel color values and the observation angle are obtained by fitting through maximum likelihood estimation and are recorded as color value space curves; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
and the color difference comparison module is used for shifting and overlapping the color value mean value space curves of different partitions on an observation angle shaft, calculating the Frechet distance between the color value mean value space curves of different partitions, and when the Frechet distance respectively corresponding to the water-soluble luminous paint to be detected and the standard paint exceeds a set distance threshold, failing to meet the requirements of the color difference between the water-soluble luminous paint to be detected and the standard paint.
Compared with the prior art, the invention has the beneficial effects that: the problems that color difference exists along with the observation angle in the color of the water-soluble luminous coating material so that color difference comparison is difficult to carry out are solved, meanwhile, the difficulty of color difference identification is simplified by utilizing an image processing technology, and the cost of purchasing a color difference instrument for color difference identification is reduced.
Drawings
FIG. 1 is a block diagram showing a method for detecting the performance of a water-soluble luminous paint according to the embodiment 1 of the present invention;
FIG. 2 is a diagram showing the construction of a device for detecting the performance of a water-soluble luminous paint according to the embodiment 1 of the present invention;
FIG. 3 is a schematic view of the observation angle of embodiment 1 of the present invention;
1-a tray; 2-a separator; 3-partitioning; 4-vertical columns; 5-camera.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Before the example, the application scenario of the invention is described, the color difference detection of the luminous paint can be completed based on the high-resolution color difference detector, and the reason is that the light source of the color difference detector is stable, the brightness, the color temperature and the like of the light source are regulated by precise instruments, and the light source is high in stability. Secondly, the color difference detector can accurately measure the irradiation angle and the observed color, and particularly for noctilucent paint, the color displayed by the color difference detector is more sensitive to the irradiation angle of a light source and even to the measurement of the temperature, humidity and ultraviolet radiation at that time than that of common paint. Because the color difference detector with higher precision is more expensive, each batch of samples on site needs to be sent to a checking center for checking, if the color difference detector is not used, various uncontrollable variables of the color difference process can be overcome, and the color difference checking process can be more accurate and convenient.
Example 1: as shown in fig. 1 and 2, the embodiment provides a method for detecting performance of a water-soluble luminous paint, which is applied to a device for detecting performance of a water-soluble luminous paint, the device comprises a tray 1 for containing the water-soluble luminous paint, a vertical column 4 is arranged in the center of the tray 1, a camera 5 is arranged at the top end of the vertical column 4, the tray 1 is provided with at least two independent partitions 3, the partitions 3 are separated by using a partition plate 2, and the partition plate 2 is vertical and is intersected with the vertical column 4;
illustratively, for example, a standard paint and two other water-soluble luminous paints to be detected are taken, wherein the standard paint is a paint required by a customer or is already used on site, and the two other water-soluble luminous paints to be detected are paints of other batches or other factories, and color difference between the two water-soluble luminous paints and the standard paint is required to be detected, so that whether a product meets the color difference requirement is checked. At this time, 3 partitions of the tray 1 are required to be used. It is emphasized that the purpose of the inventive concept is to solve the problem of measuring color difference in the same scene, namely, the luminous paint needs to overcome the problem that the temperature, humidity and ultraviolet radiation are more sensitive than the common paint, and the problem that the brightness of the light source changes at the same time, so that the external environment can be eliminated as much as possible by measuring in the same environment. It should be noted that from the view angle of the camera, the night-light paint exhibits a color change that is more easily changeable than a normal paint, i.e. different view angles result in different color feedback, from the view angle of the camera extending from the vertical post 4 all the way to the edge of the tray 1.
The method comprises the following steps:
s1, taking at least one water-soluble luminous paint and standard paint to be detected as detection samples, respectively pouring different detection samples into different partitions 3 of a tray 1, and waiting for the detection samples to be stationary when the heights of the detection samples reach the calibrated scales;
illustratively, the height of the test specimen reaching the calibrated scale does not guarantee exactly the same height, since the experimenter does not guarantee exactly the same height by the naked eye when operating, and we will follow to overcome this difficulty.
The position of the baffle plate 2 and the area for detecting the sample are acquired through the camera 5, and a ray path is drawn by taking the center of intersection of the baffle plate 2 as a round point and the pixel color value on the ray path is read.
The exemplary steps are that when the tray 1 is irradiated by parallel light, an image of a detection sample is obtained through the camera 5 and is recorded as a first image, the first image corrects the visual angle, the area of the detection sample on the first image is searched and recorded as a second image, the position of the partition board 2 is detected on the second image, and the areas corresponding to the detection samples in different partitions are marked on the second image according to the position of the partition board 2; searching the center of intersection of the partition plates 2 on the second image to serve as a circle center, drawing a ray path on the second image by taking the circle center as an endpoint, enabling a region corresponding to a detection sample in the same partition to pass through at least two ray paths, and reading pixel color values on the ray paths;
illustratively, we use the way in which the image corrects the perspective view to spread the side-captured image into a planar image, facilitating the calculation and sampling of pixel color values. The position of the baffle can be detected by an edge detection algorithm such as a Canny algorithm, an image area of interest, namely an area where a detection sample is located is scratched out, and an image of the part is taken as a study object. At this time, we distinguish different detection samples through the position of the baffle, and sample in the image area that different detection samples correspond to, along the ray path of centre of a circle, namely sample the pixel color value that changes along with the observation angle, many ray paths will be used later, because there is less bubble or impurity probably to have after the coating is static, leads to there is the error in the pixel color value of measuring.
S2, sequentially taking pixel color values on the same ray path as discrete points according to an observation angle to be arranged in a coordinate axis, and fitting by using maximum likelihood estimation to obtain a mapping curve of the pixel color values and the observation angle, wherein the mapping curve is recorded as a color value space curve; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
illustratively, the dimensions of the discrete points are partitioned according to a color gamut space, such as pixel color values employingLab mode, L, a and b are at different angles of viewRespectively define perpendicular to the observation angleAfter the discrete points are distributed, the optimal color value space curve is calculated by using maximum likelihood estimation in space. The ray path belongs to a straight line path, errors exist in pixel color values on the path, and the optimal color value space curve is calculated to avoid lines with "pits" caused by the errors. The fact that the color value space curves of the same partition are shifted and overlapped on the observation angle axis is due to the problem of the observation angle, the planes of the reflected light of the paint surfaces of the same partition are basically horizontal, the pixel color values of the same observation angle are theoretically consistent, but external parallel light is not completely parallel, an included angle with the paint planes can exist, and the observation angle is inconsistent due to phase change; meanwhile, the camera cannot ensure that the camera is absolutely vertical to the tray, and the possible observation angle is deviated to one side. Because the color value space curves of the same detection sample are basically consistent, the color value space curves are free from chromatic aberration, and only the chromatic aberration of an external instrument causes a displacement phenomenon of a reference of an observation angle, so that the color value space curves of the two detection sample are only required to be displaced and overlapped. The method is characterized in that the average value of the color value space curves after shifting and overlapping is calculated when the color values of the color value space curves are at the same observation angle is recorded as an average color value, the mapping curve of the average color value and the observation angle is drawn and recorded as a color value average value space curve, the purpose is to reduce errors existing when sampling is carried out according to a single ray path, because the color value space curves are in a fitting mode and errors possibly exist, the average value of the color value space curves is calculated through a plurality of curves of the same detection sample, and the effect on the whole curves is reduced by adjusting the errors.
S3, shifting and overlapping the color value mean value space curves of different partitions on an observation angle axis, and calculating the Frechet distance between the color value mean value space curves of different partitions, wherein when the Frechet distance respectively corresponding to the water-soluble luminous paint to be detected and the standard paint exceeds a set distance threshold, the color difference between the water-soluble luminous paint to be detected and the standard paint does not meet the requirement.
Illustratively, as shown in fig. 3, the shift overlapping of the color value mean space curves of different partitions on the observation angle axis is due to the problem of observation angle, besides that the external parallel light is not completely parallel, an included angle with the paint plane may exist, and the observation angle is not consistent due to phase change; the camera cannot ensure that the camera is absolutely vertical to the tray, and the possible observation angle is deviated to one side; also the coating heights of the different sections, although reaching the nominal height, cannot be guaranteed to be free of errors, so that the effect of these errors can be reduced by shifting the overlap. The method can obtain curve fitting degree under different observation angles by calculating the Frechet distance between the color value mean value space curves, so that the color difference value can be objectively evaluated.
Further, the method for correcting the viewing angle of the first image and searching the area of the detection sample on the first image is recorded as a second image, and comprises the following steps:
passing the first image through a perspective transformation matrixTransforming to obtain standard image, perspective transformation matrixThe method comprises the following steps:；
wherein the method comprises the steps of、、Andis a transformation parameter，Andis the coordinates of the center point of the image; detecting edges of the standard image through a Canny algorithm to obtain the edge position of the tray 1, and obtaining an area surrounded by the edge position of the tray 1 through the edge position of the tray 1 to serve as an area of a detection sample on the first image;
illustratively, the edge position of the tray 1 is easy to mark and obtain, and the specific way is to set some obvious marks so that an image processing algorithm can be positioned quickly, and the processing flow is simplified; for example, the partitions are straight lines, arc-shaped, and the area for detecting the sample can be obtained completely through the positions of a plurality of points.
The acquisition mode of the transformation parameters comprises marking anchor points of four non-collinear anchoring positions on the edge position of the tray 1 before the performance detection of the water-soluble luminous paint, respectively shooting the image of the tray 1 from the position of a camera installed on the vertical upright post 4 and the position right above the tray 1 as a first view and a second view, respectively, and marking the sitting position of the anchor point on the first view as a sitting position of the anchor pointThe coordinates of the anchor point on the second view are recorded asWhereinIs the firstAnchor points; four groups of functions are constructed through the coordinates of the same anchor point in the first view and the second view, wherein the four groups of functions are as follows:
and；
Wherein the method comprises the steps of=1, 2, 3 and 4,andis the coordinates of the center point of the image; obtaining transformation parameters through the four groups of functions、、And。
further, the method for drawing the ray paths on the second image by taking the circle center as an endpoint, enabling the region corresponding to the detection sample in the same partition to pass through at least two ray paths, and reading the pixel color values on the ray paths further comprises:
drawing ray paths towards the edge position of the tray 1 by taking the circle center as an end point, reading RGB values of pixel grids of the ray paths from the circle center to the edge position of the tray 1, and drawing at least two ray paths by the same partition according to the partition 2 according to the equal division angle; the RGB values of the pixel grid are sequentially converted into Lab values as pixel color values.
Illustratively, it is simple and convenient for the camera to acquire RGB values, which are the color value patterns commonly used by display devices, such as displays, cell phone screens, etc., and at low cost. The Lab color space is designed to more closely approximate the color perception of human vision such that mathematical differences between colors more directly reflect visual differences.
Further, the method for sequentially converting the RGB values of the pixel grid into Lab values as pixel color values comprises the following steps:
RGB values are changed from original [0,255 ]]Normalized to [0,1 ]]Obtaining、Andwill be、Andconversion to linear RGB by a first conversion formula、Andwherein the first conversion formula is:；
will beConversion intoThe formula of (2) applies equally toAndrespectively transformed to obtainAnd；
will be、Andrespectively converting into normalized XYZ values through a second conversion formula, wherein the second conversion formula is as follows:；
normalized XYZ value、Andwherein，，Will be、Andnonlinear transformation correction is carried out through a third transformation formula to obtain、Andwherein the third conversion formula is:；
will beConversion intoThe formula of (2) applies equally toAndrespectively transformed to obtainAnd；
will be、Andconverting to obtain pixel color value, lab value, wherein，，。
Further, the method for fitting a mapping curve for obtaining pixel color values and observation angles by using maximum likelihood estimation further comprises the following steps:
sequentially adjusting Lab values according to the observation anglesSequentially as discrete points arranged in a coordinate axis, each observation angleWith a corresponding set of、Andthe value is recorded asThe method comprises the steps of carrying out a first treatment on the surface of the The saidMeets the normal distribution of multiple elementsLikelihood function of mapping curveThe method comprises the following steps:；
wherein the method comprises the steps ofWhileRespectively representing model parameters of theta, N is the sampling number of LAB values,to obtain the variance of the Lab value, the model parameters are obtained by taking the derivative of the likelihood function by gradient descent method and when the derivative is 0Obtaining a mapping curve as by model parametersWhereinRepresenting any one of L, a and b values.
For example, the color value errors are understood in the present inventive concept to be normal distributions in nature, and the curve with the smallest product of the error values is determined by the law of the color value errors, that is to say the model parameters of the curve are obtained by likelihood estimation.
Further, the method for shifting and overlapping the plurality of color value space curves of the same partition on the observation angle axis comprises the following steps: taking one of the color value space curves as a first curve and equally taking the first curveThe set of points isThe other color value space curve which is shifted and overlapped at the same time is marked as a second curve and m point sets are equidistantly takenThe method comprises the steps of carrying out a first treatment on the surface of the By moving vectorsMoving the second curve to the first curve, the sum of squared Euclidean distances of the first curve and the second curveThe method comprises the following steps:；
the coordinate data of the point set is input to obtain、、Andunder the condition thatThereby shifting and overlapping the second curve to the first curve.
The distance in the inventive concept takes the euclidean distance as the degree to which it is determined whether the curves are shifted to overlap, and other distances such as the pull-type distance, etc. are within the scope of the inventive concept that can be radiated.
Further, the equidistant ones are takenThe method for the point set comprises the following steps: taking the observation angle from the first curveThe minimum time is taken as the first pointTaking the same observation angle on the second curveAs the first pointFrom the first point along the viewing angleEquidistant selection of the direction of increase leavesA set of points; the angle of observationThe first point at maximum corresponds to the first curve or the second curve at the tray edge positionPoints on the curve.
Illustratively, the inventive concept selects the first point from the most easily identified found tray 1 edge position as the anchor point, and it is relatively simple to find other locations equidistant after finding the first point.
Further, the method for setting the distance threshold value comprises the following steps: and respectively setting distance thresholds under different observation angles, wherein the distance thresholds are set according to the color difference recognition sensitivity of human eyes under different observation angles.
Illustratively, the luminous paint shows color change which is easier to change than that of the common paint, namely different observation angles lead to different color feedback, and the recognition capability of human eyes on chromatic aberration at different observation times is different, so that a distance threshold value is required to be set at different observation angles for the luminous paint, thereby meeting the recognition capability with higher precision. That is, the common paint ignores the influence of the observation angle on the color difference, and the noctilucent paint needs to be considered.
Example 2: based on the same inventive concept, the embodiment also provides a water-soluble luminous paint performance detection system which is applied to a water-soluble luminous paint performance detection device, wherein the detection device comprises a tray 1, a vertical column 4 is arranged in the center of the tray 1, a camera 5 is arranged at the top end of the vertical column 4, the tray 1 is provided with at least two independent partitions 3, the partitions 3 are separated by using a partition plate 2, and the partition plate 2 is vertical and is intersected with the vertical column 4; the tray 1 is used for accommodating detection samples, the detection samples comprise at least one water-soluble luminous paint and standard paint to be detected, different subareas are used for accommodating different detection samples, and calibrated scales are arranged in the subareas for verifying that the detection samples reach the height; the system comprises:
the image acquisition module is used for acquiring the position of the baffle plate 2 and the area for detecting the sample through the camera 5, drawing a ray path by taking the center of intersection of the baffle plate 2 as a round point and reading pixel color values on the ray path. The method comprises the following specific steps: when the tray 1 is irradiated by parallel light, an image of a detection sample is acquired through the camera 5 and is recorded as a first image, the first image is corrected for viewing angle, the area of the detection sample on the first image is searched for and is recorded as a second image, the position of the partition board 2 is detected on the second image, and the areas corresponding to the detection samples in different partitions are marked on the second image according to the position of the partition board 2; searching the center of intersection of the partition plates 2 on the second image to serve as a circle center, drawing a ray path on the second image by taking the circle center as an endpoint, enabling a region corresponding to a detection sample in the same partition to pass through at least two ray paths, and reading pixel color values on the ray paths;
the color difference curve module is used for sequentially arranging pixel color values on the same ray path as discrete points in a coordinate axis according to an observation angle, and mapping curves of the pixel color values and the observation angle are obtained by fitting through maximum likelihood estimation and are recorded as color value space curves; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
and the color difference comparison module is used for shifting and overlapping the color value mean value space curves of different partitions on an observation angle shaft, calculating the Frechet distance between the color value mean value space curves of different partitions, and when the Frechet distance respectively corresponding to the water-soluble luminous paint to be detected and the standard paint exceeds a set distance threshold, failing to meet the requirements of the color difference between the water-soluble luminous paint to be detected and the standard paint.
It should be noted that, regarding the system in the above embodiment, the specific manner in which the respective modules perform the operations has been described in detail in the embodiment regarding the method, and will not be described in detail herein.
Finally, it should be noted that: although the present invention has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present invention.
Claims (10)
1. The water-soluble luminous paint performance detection method is characterized by being applied to a water-soluble luminous paint performance detection device, wherein the detection device comprises a tray for containing the water-soluble luminous paint, a vertical column is arranged in the center of the tray, a camera is arranged at the top end of the vertical column, the tray is provided with at least two independent partitions, the partitions are separated by using a partition plate, and the partition plate is vertical and intersected with the vertical column; the method comprises the following steps:
taking at least one water-soluble luminous paint and standard paint to be detected as detection samples, respectively pouring different detection samples into different partitions of a tray, and waiting for the detection samples to be stationary when the heights of the detection samples reach the calibrated scales; acquiring the position of the baffle plate and the area for detecting the sample through the camera, drawing a ray path by taking the center of intersection of the baffle plate as a circular point, and reading pixel color values on the ray path;
sequentially taking pixel color values on the same ray path as discrete points according to an observation angle to be arranged in a coordinate axis, and using maximum likelihood estimation to fit a mapping curve for obtaining the pixel color values and the observation angle to be recorded as a color value space curve; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
shifting and overlapping the color value mean value space curves of different partitions on an observation angle axis, and calculating the French distance between the color value mean value space curves of different partitions; when the Frechet distance respectively corresponding to the water-soluble luminous paint and the standard paint to be detected exceeds a set distance threshold, the chromatic aberration is not in accordance with the requirement.
2. The method for detecting the performance of the water-soluble luminous paint according to claim 1, wherein the method for acquiring the position of the partition board and the area of the detection sample by the camera, drawing a ray path by taking the center of intersection of the partition boards as a round point and reading pixel color values on the ray path comprises the following steps:
when the tray is irradiated by parallel light, an image of a detection sample is acquired through a camera and is recorded as a first image, the first image is corrected for a visual angle, an area of the detection sample on the first image is searched for and is recorded as a second image, the position of a baffle plate is detected on the second image, and areas corresponding to the detection samples in different areas are marked on the second image according to the position of the baffle plate; and searching the center of the intersection of the partition plates on the second image to serve as a circle center, drawing a ray path on the second image by taking the circle center as an endpoint, enabling the area corresponding to the detection sample in the same partition to pass through at least two ray paths, and reading pixel color values on the ray paths.
3. The method for detecting the performance of the water-soluble luminous paint according to claim 2, wherein the method for correcting the visual angle of the first image and searching the area of the detection sample on the first image is recorded as a second image comprises the following steps:
passing the first image through a perspective transformation matrixTransforming to obtain standard image, perspective transformation matrix->The method comprises the following steps:
；
wherein the method comprises the steps of、/>、/>And->Is a transformation parameter->And->Is the coordinates of the center point of the image; detecting edges of the standard image through a Canny algorithm to obtain the edge position of the tray, and obtaining an area surrounded by the edge position of the tray through the edge position of the tray to serve as an area of a detection sample on the first image;
the manner of obtaining the transformation parameters includes,
before the performance detection of the water-soluble luminous paint, marking the anchor points of four non-collinear anchoring positions on the edge position of the tray, respectively shooting the image of the tray from the position of a camera installed on a vertical upright post and the position right above the tray as a first view and a second view, respectively, and marking the sitting mark of the anchor point on the first view asThe coordinates of the anchor point on the second view are recorded asWherein->Is->Anchor points; four groups of functions are constructed through the coordinates of the same anchor point in the first view and the second view, wherein the four groups of functions are as follows:
and
；
Wherein the method comprises the steps of=1, 2, 3 and 4, +.>And->Is the coordinates of the center point of the image; obtaining transformation parameters by the four groups of functions>、/>、/>And->。
4. The method for detecting the performance of the water-soluble luminous paint according to claim 2, wherein the method for drawing ray paths on the second image by taking a circle center as an endpoint, wherein the area corresponding to the detection sample in the same partition passes through at least two ray paths, and the method for reading pixel color values on the ray paths further comprises:
drawing ray paths towards the edge position of the tray by taking the circle center as an endpoint, reading RGB values of pixel grids of the ray paths from the circle center to the edge position of the tray, and drawing at least two ray paths by the same partition according to partition positions and equal division angles; the RGB values of the pixel grid are sequentially converted into Lab values as pixel color values.
5. The method for detecting the performance of the water-soluble luminous paint according to claim 4, wherein the method for sequentially converting the RGB values of the pixel grid into Lab values as pixel color values comprises the following steps:
RGB values are changed from original [0,255 ]]Normalized to [0,1 ]]Obtaining、/>And->Will->、/>And->Conversion to linear RGB by the first conversion formula +.>、/>And->Wherein the first conversion formula is:
；
will beConversion to->The formula of (2) applies equally to +.>And->Respectively transforming to obtain->And->；
Will be、/>And->Respectively converting into normalized XYZ values through a second conversion formula, wherein the second conversion formula is as follows:
；
normalized XYZ value、/>And->Wherein->，/>，/>Will->、/>And->Nonlinear transformation correction is carried out through a third transformation formula to obtain +.>、/>And->Wherein the third conversion formula is:
；
will beConversion to->The formula of (2) applies equally to +.>And->Respectively transforming to obtain->And->；
Will be、/>And->Converting to obtain pixel color value, lab value, wherein +.>，/>，。
6. The method for detecting the performance of the water-soluble luminous paint according to claim 5, wherein the method for fitting a mapping curve for obtaining pixel color values and observation angles by using maximum likelihood estimation further comprises:
sequentially adjusting Lab values according to the observation anglesSequentially as discrete points arranged in a coordinate axis, wherein each observation angle is +.>With a corresponding group->、/>And->The value is recorded as +.>The method comprises the steps of carrying out a first treatment on the surface of the Said->Is in accordance with the normal distribution of multiple elements>Likelihood function of mapping curve->The method comprises the following steps:
；
wherein the method comprises the steps ofAnd->Respectively representing model parameters related to theta, N is the sampling number of LAB values, +.>For the variance of the sampled Lab values, the model parameters are determined by gradient descent method when the likelihood function is derivative and the derivative is 0>The mapping curve is obtained by model parameters as +.>Wherein->Representing any one of L, a and b values.
7. The method for detecting the performance of the water-soluble luminous paint according to claim 1, wherein the method for shifting and overlapping the color value space curves of the same partition on the observation angle axis comprises the following steps:
taking one color value space curveMarked as a first curve and taken equidistantlyThe set of points is->The other color value space curve which is shifted and overlapped at the same time is marked as a second curve and m point sets are equidistantly takenThe method comprises the steps of carrying out a first treatment on the surface of the By means of a motion vector->Moving the second curve to the first curve, the sum of squared Euclidean distances of the first curve and the second curve +.>The method comprises the following steps:
；
the coordinate data of the point set is input to obtain、/>、/>And->Under the condition->Thereby shifting and overlapping the second curve to the first curve.
8. The method as claimed in claim 7The method for detecting the performance of the water-soluble luminous paint is characterized in that the water-soluble luminous paint is taken at equal intervalsThe method for the point set comprises the following steps:
taking the observation angle from the first curveThe smallest hour is the first point +.>The same observation angle is taken on the second curve +.>When as the first point->From the first point along the viewing angle +.>The increased direction is equally selected to be left +.>A set of points; the observation angle->The first point at maximum corresponds to a point on the first curve or the second curve at the tray edge position.
9. The method for detecting the performance of the water-soluble luminous paint according to claim 1, wherein the method for setting the distance threshold comprises the following steps:
and respectively setting distance thresholds under different observation angles, wherein the distance thresholds are set according to the color difference recognition sensitivity of human eyes under different observation angles.
10. The water-soluble luminous paint performance detection system is characterized by being applied to a water-soluble luminous paint performance detection device, wherein the detection device comprises a tray, a vertical column is arranged in the center of the tray, a camera is arranged at the top end of the vertical column, the tray is provided with at least two independent partitions, the partitions are separated by using a partition plate, and the partition plate is vertical and is intersected with the vertical column; the tray is used for accommodating detection samples, the detection samples comprise at least one water-soluble luminous paint and standard paint to be detected, different subareas are used for accommodating different detection samples, and calibrated scales are arranged in the subareas for verifying that the detection samples reach the height; the system comprises:
the image acquisition module is used for acquiring the position of the partition board and the area for detecting the sample through the camera, drawing a ray path by taking the center of intersection of the partition boards as a round point and reading pixel color values on the ray path;
the color difference curve module is used for sequentially arranging pixel color values on the same ray path as discrete points in a coordinate axis according to an observation angle, and mapping curves of the pixel color values and the observation angle are obtained by fitting through maximum likelihood estimation and are recorded as color value space curves; shifting and overlapping a plurality of color value space curves in the same partition on an observation angle axis, calculating the average value of the color values of the color value space curves subjected to shifting and overlapping at the same observation angle, marking the average value as an average color value, and drawing a mapping curve of the average color value and the observation angle as a color value average value space curve;
the color difference comparison module is used for shifting and overlapping the color value mean value space curves of different partitions on an observation angle axis, and calculating the French distance between the color value mean value space curves of different partitions; when the Frechet distance respectively corresponding to the water-soluble luminous paint and the standard paint to be detected exceeds a set distance threshold, the chromatic aberration is not in accordance with the requirement.
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