CN107944107A - A kind of single silver powder computer for colouring method and system for automobile metal paint - Google Patents
A kind of single silver powder computer for colouring method and system for automobile metal paint Download PDFInfo
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Abstract
The invention discloses a kind of single silver powder computer for colouring method and system for automobile metal paint, this method accurately describes the color attribute of colorant using color theory, first establish the optical data of the base color of metallic paint, store it in database, when needing to carry out computer for colouring prediction, read the color data of target vehicle, then in called data storehouse associated metal paint optical data, accurately prediction is carried out to calculate, so as to the process being accurately formulated, the automation color matching of multi-angle list silver powder automobile metal paint is realized.The present invention can effectively solve the problem that the problem of time-consuming present in car refinishing paint industry, of high cost and effect is poor, by introduce can accurate measurement color data multi-angle spectrophotometer, and propose metallic paint mixing color matching for the computer for colouring of metallic paint, to realize that the automated high-precision of multi-angle list silver powder automobile metal paint is matched colors, there is high-timeliness, high flexibility and high-precision.
Description
Technical Field
The invention relates to a metal paint color matching technology in the automobile refinishing paint industry, in particular to a single silver powder computer color matching method and a single silver powder computer color matching system for automobile metal paint.
Background
The computer color matching can provide guidance for specific production practices and simplify the color matching process by accurately describing the color attributes of the pigments by utilizing the theory of coloristic. The computer color matching can be widely applied to the fields of paint, textile, ready-made clothes, automobiles and the like, which relate to the color industry. Computer color matching technology is started in the 30's of 20 th century, CIE (International Commission on illumination) creates a tristimulus-value colorimetry system, and Hardy successfully designs an automatic recording type reflectivity multi-angle spectrophotometer; in 1931 Kubelka-Munk proposes the theory that light is absorbed and scattered in opaque medium, namely the Kubelka-Munk theory, which is the theoretical basis of most computer color matching systems at the present time, is called K-M theory for short, and the K-M theory is linked with the relationship between the reflectivity R of an object and the absorption coefficient K and the scattering coefficient S, thereby laying a foundation for realizing computer color matching. The 20 th century, 40 s, was the time of computer color matching technology development, and the earliest color matching systems were completed by Park of cyanamide corporation and dunnann design of the united kingdom paint institute. Despite the low color matching efficiency of this system, its emergence marks the arrival of a new era in the implementation of computer color matching. The 20 th century and the 50 th century are important times in the history of computer color measuring and matching. The first analog specialized color matching computer developed by Davidson and Hemnmendinger was installed in the united states in 1958, marking the formal set-up of computer color matching systems. The 20 th century and the 60 th era are the times of computer color measurement and matching. In this time, e.i. du Pont de Nemours and Imperial Chemical (ICI) were successively announced to provide computer color matching services to clients, making computer color matching thrive. At present, in industrially developed countries, industries related to coloring, such as textile printing and dyeing, dye and pigment manufacturing, paint, plastic coloring processing, ink and the like, generally adopt a computer color matching system as a powerful tool for product development, production, quality control and sale, and the popularization rate is very high. Many research units and manufacturers are engaged in the development of automatic color measuring and matching systems, and corresponding products are continuously put on the market, such as Datacolor, macbeth, shelyn, hunterlab, etc. in the united states, zeiss, optronic, oriental in italy, minotao in japan, etc. The products bring production science, high efficiency and economic benefits to users.
In China, theoretical research on computer color matching and development of system software are relatively backward, and a computer color matching technology is still in a starting stage. The Shanghai textile academy introduced the first automatic color measuring and matching instrument from OPTON, germany, until the beginning of the 80's of the 20 th century. The development and research of domestic electronic color matching systems are carried out in 80 years in China. Shenyang chemical research institute started to research color matching systems from 1984, and introduced Chinesian color matching Chinese software, which is the earliest Chinese software in China. The system has been applied in the fields of dye, printing and dyeing, wool spinning, plastics, paint, printing ink and the like. 2001 national defense science and technology university and world science and technology company jointly developed a simulation system for paint color matching, and the system can well realize the color matching of paint light color and is widely applied to the paint industry. However, the color quality control and formula prediction process of a plurality of production units still mainly depends on the experience and visual judgment of workers at home, thereby seriously restricting the development of color related industries in China.
In the automotive refinish industry, there are three main types of paints used: plain paints, metallic paints and pearlescent paints. The common paint is the most common one and belongs to the most basic vehicle paint, the synthetic material of the common paint comprises resin, pigment and additive, and the reflectivity spectrum of the plain paint at all angles is consistent from the optical property, namely, the paint is isotropic; the metallic paint is added with aluminum powder, can generate a flickering effect and improve the aesthetic property, and the bright-dark change effect of the metallic paint is mainly represented by the inconsistent color depth seen from the front and the side, has the maximum reflection effect seen from the front and can give people a visual feeling of bright color tone; when the color is seen from the side, the reflectivity is greatly reduced, and the color tone is darkened; the pearlescent paint is paint added with mica sheets, can generate rainbow effect similar to pearls, has anisotropy in optics like metallic paint, and changes in color depth and saturation under different observation angles. The metallic paint is subdivided into silver powder paint and metallic color mother paint, wherein the silver powder paint is responsible for adjusting the reflectivity difference of each angle of the color, and the metallic color mother paint is responsible for the hue of the specific color.
In the automobile refinishing paint industry, manual paint mixing is still prevalent at present, namely, a technician manually mixes color master batch according to the color of an automobile needing to be refinished to obtain paint with a color close to a target color. This is laborious and time consuming and difficult to ensure with respect to accuracy and stability. Another approach is computer paint mixing, where the computer is actually a large database of paint formulations that store standard formulations for various paints. Various paints are marked by numbers, and a repair shop inputs the numbers of vehicles to be painted into a computer to obtain a standard formula of the paint according to the numbers of the vehicles to be painted, and paints are mixed according to the formula. However, this process still has drawbacks: firstly, the problem of color difference is difficult to be solved under the conditions that all vehicle types are difficult to cover and the same-grade vehicle types are different in vehicle age and batch. Therefore, when using a computer paint mixing method, 90% of the cases still need to be adjusted manually. Therefore, the current color matching method for plain paint, metallic paint and pearlescent paint in the automobile refinishing paint industry can not be used for manual color matching of technical workers, and has the problems of high cost, low efficiency and the like.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the problems that in the current automobile refinishing paint industry, a computer automatic color matching method is lacked in the color matching process of the automobile refinishing paint of the metal paint, and the color difference which cannot be solved according to the existing formula color matching exists, the invention provides a single-silver powder computer color matching method and a single-silver powder computer color matching system for the automobile metal paint. It should be noted that, the multi-angle here means that the reflectivity spectrum of the metallic paint is different at each angle, and the metallic paint presents anisotropy; the single silver powder means that the invention is limited to a method for carrying out color matching by using one silver powder and a plurality of metallic paint color masters, and the formula of color matching and mixing is summarized by a large amount of experimental experiences.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides a single silver powder computer color matching method for automobile metallic paint, which comprises the following implementation steps:
1) For 100% silver paint and m kinds of metal color mother paint, obtaining virtual K/S value and recording as (K/S) for 100% silver paint w And obtaining a virtual K/S value for each metal paint i with the concentration of 100% and recording the value as (K/S) i Wherein the virtual K/S value is the ratio of the absorption coefficient to the reflection coefficient, and the value range of i is [1,m ]]；
2) Aiming at each metal color mother paint i, mixing the metal color mother paint i and the silver paint in different proportions, reading the reflectivity R of a mixed color sample through a multi-angle spectrophotometer, and calculating the virtual reflectivity R v Then calculating the virtual K/S value of the mixed paint under different concentrations through a K-M theory to be recorded as (K/S) m Finally, the virtual K/S value (K/S) at each concentration j is determined m Fitting is carried out, and a function expression of the virtual K/S value of each metal color mother paint i at any concentration is obtained, so that a basic database of each metal color mother paint i is constructed;
3) Obtaining the reflectivity of the target vehicle paint surface, obtaining a virtual K/S value and recording as (K/S) s ；
4) For each metal color mother paint i to be matched, acquiring a virtual K/S value (K/S) of the metal color mother paint i at a specified initial concentration according to a basic database i ；
5) Constructing a tristimulus value equation shown in formula (1) and solving the equation to obtain an initial formula [ C 0 ,C 1 ,C 2 ,…,C n ]In which C is 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percent of the 2 nd metallic color mother paint, C n The mass percentage of the nth metal color mother paint is shown;
in the formula (1), Δ X represents the difference between the tristimulus values X of the target color block and the color block of the prediction formula, and Δ Y represents the tristimulus values of the target color block and the color block of the prediction formulaY, delta Z represents the difference between the tristimulus values Z of the target color block and the predicted formula color block, E represents the constant of broad spectrum energy distribution in CIE-1931Represents the standard colorimetric observer spectral stimulus X in the CIE-XYZ system and is a constant data,represents the standard colorimetric observer spectral stimulus Y in the CIE-XYZ system and is a constant data,representing a standard chromaticity observer spectral stimulus value Z in a CIE-XYZ system and being constant data, R representing the virtual reflectance of the target color block, C 0 Is the mass percent of the silver paint, C 1 Is the mass percentage of the 1 st metallic color mother paint, C n D (K/S) represents the differential of the virtual K/S value of the target color block in the K-M theory and is the mass percentage of the nth metallic color mother paint s Virtual K/S value (K/S) representing target color patch w Represents the virtual K/S value of 100% concentration silver paint, (K/S) 1 Virtual K/S value (K/S) of 1 st metallic color mother paint at specified initial concentration n The virtual K/S value of the nth metal color mother paint in the designated initialization concentration is shown, and delta lambda represents the sampling interval in the visible light wavelength range;
6) Initializing an iteration time threshold idex and an iteration time variable j, and jumping to the next step to start iterative execution;
7) Taking the initial formula as a formula to be iterated during first iteration, otherwise taking the initial formula obtained in the previous iteration as the formula to be iterated, and respectively calculating the concentration of various metallic color mother paints relative to the silver powder paint in the formula to be iterated as the current iteration concentration;
8) Aiming at each metal color mother paint i, acquiring a virtual K/S value of the metal color mother paint i under the current iteration concentration according to a basic database;
9) Let the values of DeltaX, deltaY, deltaZ all be 0, and substitute into equation (1) to perform the iterationSolving to obtain a new formula [ C 0 ,C 1 ,C 2 ,…,C n ]In which C is 0 Is the mass percentage of the silver paint, C n The mass percentage of the nth metal color mother paint is shown;
10 Adding 1 to the variable j of the iteration times, judging whether the variable j of the iteration times is smaller than the threshold idex of the iteration times, and if so, skipping to execute the step 7); otherwise, the new recipe [ C ] obtained in the last round is used 0 ,C 1 ,C 2 ,…,C n ]An output, wherein C 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percentage of the 2 nd metallic color mother paint, C n Is the mass percentage of the nth metal color mother paint.
Preferably, the detailed steps of acquiring the virtual K/S value in step 1) and step 3) include: preparing a sample plate of the paint to be detected, reading the reflectivity R of the sample plate by using a multi-angle spectrophotometer, wherein the reflectivity R is reflectivity data of 5 angles, and then calculating according to a formula (2) to obtain the reflectivity R under a virtual angle v Further calculating according to a formula (3) to obtain a virtual K/S value;
in the formula (2), ω is i Representing the weight of each defined angle, R i Representing the reflectivity at each angle.
In the formula (3), K/S represents a calculated virtual K/S value, and R represents a virtual reflectance.
Preferably, the fitting in the step 2) specifically means fitting by adopting a least square approximation fitting algorithm, and the obtained function expression of the virtual K/S of each metal color mother paint i at any concentration is shown as a formula (4);
in the formula (4), K/S represents a virtual K/S value of the metallic color base paint i at any concentration, a 1 、a 2 、b 1 、b 2 、c 1 And c 2 For the to-be-determined fit coefficient, N represents the concentration.
The invention also provides a single silver powder computer color matching system for an automobile metal paint, which comprises a computer system programmed to execute the steps of the single silver powder computer color matching method for the automobile metal paint.
The present invention also provides a computer-readable medium characterized by: the computer readable medium has stored thereon a computer program for causing a computer system to execute the steps of the aforementioned single silver powder computer coloring method for automobile metallic paint of the present invention.
The single silver powder computer color matching method for the automobile metallic paint has the following advantages: the metal paint computer color matching method accurately describes the color attribute of the pigment by using the theory of colorology, firstly establishes the optical data of the basic color of the metal paint, stores the optical data in a database, reads the target color data when needing to carry out computer color matching, calls the optical data of the related color in the database, carries out accurate prediction calculation, obtains the process of accurate formula and realizes the automatic color matching of the multi-angle single silver powder automobile metal paint. The method can effectively solve the problems of long time consumption, high cost and poor effect in the automobile refinishing paint industry, realizes automatic high-precision color matching of the multi-angle single-silver-powder automobile metal paint by introducing the multi-angle spectrophotometer capable of precisely measuring color data and providing metal paint mixed color matching aiming at computer color matching of metal color, and has the advantages of high timeliness, high flexibility and high precision.
The single silver powder computer color matching system for the automobile metallic paint comprises a computer program for executing the steps of the single silver powder computer color matching method for the automobile metallic paint, and the single silver powder computer color matching system for the automobile metallic paint also has the advantages of the single silver powder computer color matching method for the automobile metallic paint, so the details are not repeated.
Drawings
FIG. 1 is a schematic diagram of a basic process flow of a method according to an embodiment of the present invention.
Fig. 2 is a general system structure diagram of the method according to the embodiment of the present invention.
FIG. 3 is a flow chart of building a base metallic paint database in an embodiment of the present invention.
FIG. 4 is a flow chart of initial recipe calculation in an embodiment of the present invention.
FIG. 5 is a flowchart of an embodiment of the present invention for iteratively solving an exact solution.
Detailed Description
Metallic paints generally fall into two categories: silver paint and metallic mother paint. The silver paint has great influence on the reflectivity of the color at various angles; the metallic mother paint refers to metallic paints of various colors, such as yellow, red, blue, green, purple, black, etc., and is responsible for adjusting hue. The following will further describe the multi-angle single silver powder automobile metal paint computer color matching method in detail by using the silver powder paint and the three metal color mother paints as the color matching base paints.
As shown in fig. 1, the implementation steps of the single silver powder computer color matching method for the automobile metallic paint of the embodiment include:
1) For 100% silver paint and m kinds of metal color mother paint, obtaining virtual K/S value and recording as (K/S) for 100% silver paint w The virtual K/S value was obtained for each 100% concentration of metallic paint i and recorded as (K/S) i Wherein the virtual K/S value is the ratio of the absorption coefficient to the reflection coefficient, and the value range of i is [1,m ]]。
2) Aiming at each metallic color mother paint i, the metallic color mother paint i and the silver paint are respectively mixed in different proportions, the reflectivity R of the mixed color sample is read through a multi-angle spectrophotometer, and the virtual reflectivity R is calculated v Then calculating the virtual K/S value of the mixed paint under different concentrations through a K-M theory to be recorded as (K/S) m Finally, the virtual K/S value (K/S) at each concentration j is determined m And fitting to obtain a function expression of the virtual K/S value of each metal color mother paint i at any concentration, thereby constructing a basic database of each metal color mother paint i.
3) Obtaining the reflectivity of the target vehicle paint surface, obtaining a virtual K/S value and recording as (K/S) s (ii) a In this embodiment, a multi-angle spectrophotometer is used to read the reflectivity R of a target color block (visible light band is 400 to 700 nm, and a sampling point is collected every 10 nm), and then the reflectivity R at a virtual angle is calculated according to the formula (2) v Further calculating to obtain the virtual K/S value (K/S) of the target according to the formula (3) s 。
4) Referring to FIG. 4, for each metallic color mother paint i to be matched, obtaining the virtual K/S value (K/S) of the metallic color mother paint i at the designated initialization concentration according to the base database i (ii) a In this embodiment, the specified initialization concentration is specifically 0.1%, and other concentrations may be specified.
5) Referring to fig. 4, a tristimulus value equation shown in formula (1) is constructed and equation solution is performed to obtain an initial formulation [ C 0 ，C 1 ，C 2 ，…，C n ]In which C is 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percentage of the 2 nd metallic color mother paint, C n The mass percentage of the nth metal color mother paint is shown;
in the formula (1), delta X represents the difference of tristimulus values X of the target color block and the color block of the predicted formula, and delta Y represents the difference of the target color block and the predicted formulaThe difference of the tristimulus values Y of the square color blocks, delta Z of the target color block and the predicted formula color block, and E of the constant of the broad spectrum energy distribution in CIE-1931Represents the standard colorimetric observer spectral stimulus X in the CIE-XYZ system and is a constant data,represents the spectral stimulus Y of a standard colorimetric observer in the CIE-XYZ system and is a constant data,representing a standard chromaticity observer spectral stimulus value Z in CIE-XYZ system and being a constant data, R representing the reflectivity of the target color block, C 0 Is the mass percentage of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C n D (K/S) represents the differential of the virtual K/S value of the target color block in the K-M theory, and is the mass percent of the nth metal color mother paint s Virtual K/S value (K/S) representing target color patch w Virtual K/S value (K/S) representing 100% concentration of silver paint 1 Relative K/S value (K/S) of the 1 st metallic color mother paint at the designated initial concentration n The relative K/S value of the nth metal color mother paint at a specified initial concentration is shown, and the Delta lambda represents the sampling interval in the visible light wavelength range (the constant 10 nanometers is specially adopted in the embodiment); the tristimulus values are the representation of the stimulation degree of three primary colors causing human retina to feel a certain color, in 1931, CIE gives a spectrum tristimulus value curve matching any color with equal energy standard three primary colors, wherein the tristimulus values refer to CIE-XYZ tristimulus values, and the CIE-XYZ spectrum tristimulus values are obtained by mathematically transforming the CIE-RGB spectrum tristimulus values. The tristimulus equation is an equation for obtaining XYZ values of tristimulus values by associating the absorption coefficient K and the scattering coefficient S of the object.
As described above, the color matching base paints in this embodiment are silver powder paint and three metallic mother paints, and thus the tristimulus value equation shown in formula (1)In the initial formula, [ C ] 0 ，C 1 ，C 2 ，C 3 ]。
6) Initializing an iteration time threshold idex and an iteration time variable j, and jumping to the next step to start iterative execution; the iteration flow is as shown in fig. 5, referring to fig. 5, in this embodiment, the value of the initialization iteration threshold idex is 10, and the value of the iteration variable j is 1.
7) Taking the initial formula as a formula to be iterated during first iteration, otherwise taking the initial formula obtained in the previous iteration as the formula to be iterated, and respectively calculating the concentration of various metallic color mother paints relative to the silver powder paint in the formula to be iterated as the current iteration concentration; in this example, according to [ C 0 ，C 1 ，C 2 ，C 3 ]The value of (A) can be converted into the concentration [ C ] of the three metallic mother paints 1 /(C 1 +C 0 )，C 2 /(C 2 +C 0 )，C 3 /(C 3 +C 0 )]；
8) For each metal color mother paint i, acquiring a virtual K/S value of the metal color mother paint i under the current iteration concentration according to a basic database;
9) The values of delta X, delta Y and delta Z are all 0, and are substituted into equation (1) to carry out iterative solution to obtain a new formula [ C 0 ，C 1 ,C 2 ,…,C n ]In which C is 0 Is the mass percent of the silver paint, C n The mass percentage of the nth metal color mother paint is shown;
10 Adding 1 to the variable j of the iteration times, judging whether the variable j of the iteration times is smaller than the threshold idex of the iteration times, and if so, skipping to execute the step 7); otherwise, the new recipe [ C ] obtained in the last round is used 0 ,C 1 ,C 2 ,…,C n ]An output, wherein C 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percent of the 2 nd metallic color mother paint, C n Is the mass percentage of the nth metal color mother paint.
In this embodiment, the detailed steps of obtaining the virtual K/S value in step 1) and step 3) include: preparing a template for the paint to be tested, using a polygonReading the reflectivity R of the sample plate by a spectrophotometer, wherein the reflectivity R is reflectivity data of 5 angles, and then calculating the reflectivity R under a virtual angle according to a formula (2) v Further calculating according to a formula (3) to obtain a virtual K/S value;
in the formula (2), ω i Weight, R, representing each angle defined i Representing the reflectivity at each angle.
In the formula (3), K/S represents a calculated virtual K/S value, and R represents a virtual reflectance. Specifically, the step of acquiring the K/S value of the silver paint with the concentration of 100% in the step 1) comprises the following steps: preparing a sample plate of 100% silver paint, reading the reflectivity R (visible light wave band is 400-700 nm, and a sample point is collected every 10 nm) of the sample plate by using a multi-angle spectrophotometer, wherein the reflectivity R is reflectivity data of 5 angles, and then calculating according to a formula (2) to obtain the reflectivity R under a virtual angle v Further calculating according to a formula (3) to obtain a virtual K/S value of the silver paint with the concentration of 100%; the step of obtaining the virtual K/S value of the mixed sample card of each metal color mother paint i in the step 2) comprises the following steps: respectively preparing mixed sample plates of the silver paint and each metallic color mother paint i in different proportions, respectively reading the reflectivity R (visible light wave band is 400-700 nanometers, and sampling points are collected every 10 nanometers) of the sample plates by using a multi-angle spectrophotometer, and calculating the virtual reflectivity R according to a formula (2) v Then calculating the virtual K/S value of the mixed paint under different concentrations through a formula (3); the step of acquiring the virtual K/S value of the target color block in the step 3) comprises the following steps: reading the reflectivity R of the target color block by using a multi-angle spectrophotometer, and calculating according to a formula (2) to obtain the reflectivity R under a virtual angle v And further calculating according to a formula (3) to obtain a virtual K/S value of the target color block.
As shown in fig. 2, a hardware module related to the application system of the method of this embodiment is a multi-angle spectrophotometer, an optical attribute of each metal paint is determined by the multi-angle spectrophotometer, then a base database of < concentration, optical data > of the metal color mother paint is established by performing step 2) through a library establishing algorithm, a mapping relationship stored in the base database of each metal color mother paint i is < concentration, optical data >, and the optical data is a virtual K/S value, and the base database can accurately describe optical data changes caused by the concentration changes of the metal color mother paint. And after a basic database of each metal color mother paint is established, the steps 3) to 10) are executed based on a color matching algorithm, and the optical data of a plurality of mixed metal paints can be accurately calculated by applying the mixing algorithm of the metal paints, so that the optical data of the plurality of mixed metal paints can be predicted, and the automatic color matching of the multi-angle single-silver powder automobile metal paints is realized.
As shown in fig. 3, 20 concentration gradients of 1%, 2%, 4%, 6%, 8%, 12%, 16%, 24%, 32%, 40%, 48%, 56%, 64%, 72%, 80%, 90%, 92%, 95%, 97%, and 99% are selected in this embodiment to construct a base database for each of the metallic color base paints i, the number of the metallic color base paints is m (m > 1), the numbers are 1 to m, i is circularly incremented by 1 to m times, and the following operations are performed:
s1) selecting a metal color mother paint i from metal color mother paints needing to be built;
s2) aiming at the concentration of 1%, 99 g of silver powder and 1 g of metallic color mother paint i are mixed to prepare a sample plate, and a multi-angle spectrophotometer is used for reading the reflectivity data R of the sample plate 1 The reflectivity R is reflectivity data of 5 angles, and then the reflectivity R under the virtual angle is calculated according to the formula (2) v Further calculating to obtain a virtual K/S value (K/S) of the silver paint with 100% concentration according to the formula (3) 1 。
S3) aiming at the concentration of 2%, 98 g of silver powder and 2 g of metallic color mother paint i are mixed to prepare a sample plate, and a multi-angle spectrophotometer is used for reading the reflectivity data R of the sample plate 2 The reflectivity R is reflectivity data of 5 angles, and then virtual is obtained by calculation according to the formula (2)Reflectance at pseudo angle R v Further calculating to obtain a virtual K/S value (K/S) of the silver paint with 100% concentration according to the formula (3) 2 。
S4) aiming at the concentration of 4%, 96 g of silver powder and 4 g of metallic color mother paint i are mixed to prepare a sample plate, and a multi-angle spectrophotometer is used for reading the reflectivity data R of the sample plate 3 The reflectivity R is reflectivity data of 5 angles, and then the reflectivity R under a virtual angle is calculated according to a formula (2) v Further calculating to obtain a virtual K/S value (K/S) of the silver paint with 100% concentration according to the formula (3) 3 。
……
S21) aiming at the concentration of 99%, 1 g of silver powder and 99 g of metallic color mother paint i are mixed to prepare a sample plate, and a multi-angle spectrophotometer is used for reading the reflectivity data R of the sample plate 20 The reflectivity R is reflectivity data of 5 angles, and then the reflectivity R under the virtual angle is calculated according to the formula (2) v Further calculating to obtain a virtual K/S value (K/S) of the silver paint with 100% concentration according to the formula (3) 20 。
S22) considering the concentration ratio of the metallic color mother paint in the whole mixture, the virtual K/S parameter value is not a fixed value any more, but a function related to the concentration, and (K/S) 1 、(K/S) 2 、(K/S) 3 …(K/S) 20 And corresponding concentration data<1％,(K/S) 1 >、<2％,(K/S) 2 >、<4％,(K/S) 3 >…<99％,(K/S) 20 > as in formula (4)<N,K/S&And solving the values of a, b and c by adopting a least square approximation algorithm, thereby better describing the (K/S) parameters of the color paste.
In the embodiment, the fitting in the step 2) specifically means fitting by adopting a least square approximation fitting algorithm, and the obtained functional expression of the virtual K/S of each metallic color base paint i at any concentration is shown as a formula (4);
in the formula (4), K/S represents a virtual K/S value of the metallic mother paint i at any concentration, a 1 、a 2 、b 1 、b 2 、c 1 And c 2 To determine the fit coefficient, N represents the concentration.
The present embodiment also provides a single silver powder computer color matching system for an automobile metallic paint, comprising a computer system programmed to perform the steps of the single silver powder computer color matching method for an automobile metallic paint of the present embodiment.
The present embodiment also provides a computer-readable medium having stored thereon a computer program for causing a computer system to execute the steps of the single silver powder computer coloring method for automotive metallic paint of the present embodiment.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiments, and all technical solutions that belong to the idea of the present invention belong to the scope of the present invention. It should be noted that modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered as within the scope of the present invention.
Claims (5)
1. A single silver powder computer color matching method for automobile metallic paint is characterized by comprising the following implementation steps:
1) Obtaining a virtual K/S value for the silver paint with the concentration of 100 percent and recording as (K/S) for the silver paint with the concentration of 100 percent and m kinds of metal color mother paint w And obtaining a virtual K/S value for each metal paint i with the concentration of 100% and recording the value as (K/S) i Wherein the virtual K/S value is the ratio of absorption coefficient to reflection coefficient, and the value range of i is [1, m ]]；
2) Aiming at each metal color mother paint i, mixing the metal color mother paint i and the silver paint in different proportions, reading the reflectivity R of a mixed color sample through a multi-angle spectrophotometer, and calculating the virtual reflectivity R v Then calculated by K-M theoryThe virtual K/S value of the mixed paint at different concentrations is recorded as (K/S) m Finally, the virtual K/S value (K/S) at each concentration j is determined m Fitting is carried out, and a function expression of the virtual K/S value of each metal color mother paint i at any concentration is obtained, so that a basic database of each metal color mother paint i is constructed;
3) Obtaining the reflectivity of the target vehicle paint surface, obtaining a virtual K/S value and recording as (K/S) s ；
4) For each metal color mother paint i to be matched, acquiring a virtual K/S value (K/S) of the metal color mother paint i at a specified initial concentration according to a basic database i ；
5) Constructing a tristimulus value equation shown in formula (1) and solving the equation to obtain an initial formula [ C 0 ,C 1 ,C 2 ,…,C n ]In which C is 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percent of the 2 nd metallic color mother paint, C n The mass percentage of the nth metal color mother paint is shown;
in the formula (1), Δ X represents the difference of the tristimulus values X of the target color block and the color block of the prediction formula, Δ Y represents the difference of the tristimulus values Y of the target color block and the color block of the prediction formula, Δ Z represents the difference of the tristimulus values Z of the target color block and the color block of the prediction formula, and E represents the constant of the broad-spectrum energy distribution in CIE-1931Represents the standard colorimetric observer spectral stimulus X in the CIE-XYZ system and is a constant data,represents the spectral stimulus Y of a standard colorimetric observer in the CIE-XYZ system and is a constant data,representing the spectral stimulus Z of a standard-chromaticity observer in the CIE-XYZ system and being a constant data, R representing the virtual reflectivity of the target color block, C 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C n D (K/S) represents the differential of the virtual K/S value of the target color block in the K-M theory and is the mass percentage of the nth metallic color mother paint s Virtual K/S value (K/S) representing target color patch w Virtual K/S value (K/S) representing 100% concentration of silver paint 1 Virtual K/S value (K/S) of 1 st metallic color mother paint at specified initial concentration n The virtual K/S value of the nth metal color mother paint in the designated initialization concentration is shown, and the Delta lambda represents the sampling interval in the visible light wavelength range;
6) Initializing an iteration time threshold idex and an iteration time variable j, and jumping to the next step to start iterative execution;
7) Taking the initial formula as a formula to be iterated during first iteration, otherwise taking the initial formula obtained in the previous iteration as the formula to be iterated, and respectively calculating the concentration of various metallic color mother paints relative to the silver powder paint in the formula to be iterated as the current iteration concentration;
8) Aiming at each metal color mother paint i, acquiring a virtual K/S value of the metal color mother paint i under the current iteration concentration according to a basic database;
9) The values of delta X, delta Y and delta Z are all 0, and are substituted into equation (1) to carry out iterative solution to obtain a new formula [ C 0 ,C 1 ,C 2 ,…,C n ]In which C is 0 Is the mass percent of the silver paint, C n The mass percentage of the nth metal color mother paint is shown;
10 Adding 1 to the variable j of the iteration times, judging whether the variable j of the iteration times is smaller than the threshold idex of the iteration times, and if so, skipping to execute the step 7); otherwise, the new formulation obtained in the last round [ C ] 0 ,C 1 ,C 2 ,…,C n ]An output, wherein C 0 Is the mass percent of the silver paint, C 1 Is the mass percent of the 1 st metallic color mother paint, C 2 Is the mass percentage of the 2 nd metallic color mother paintRatio of (C) to (C) n Is the mass percentage of the nth metal color mother paint.
2. The single silver powder computer color matching method for automobile metallic paint according to claim 1, wherein the detailed steps of obtaining the virtual K/S value in step 1) and step 3) comprise: preparing a sample plate of the paint to be detected, reading the reflectivity R of the sample plate by using a multi-angle spectrophotometer, wherein the reflectivity R is reflectivity data of 5 angles, and then calculating according to a formula (2) to obtain the reflectivity R under a virtual angle v Further calculating according to a formula (3) to obtain a virtual K/S value;
in the formula (2), ω is i Representing the weight of each defined angle, R i Representing the reflectivity at each angle.
In the formula (3), K/S represents a calculated virtual K/S value, and R represents a virtual reflectance.
3. The single silver powder computer color matching method for the automobile metallic paint according to claim 1, wherein the fitting in the step 2) specifically comprises fitting by adopting a least square approximation fitting algorithm, and the obtained functional expression of virtual K/S of each metallic color mother paint i at any concentration is as shown in a formula (4);
in the formula (4), K/S represents a virtual K/S value of the metallic mother paint i at any concentration, a 1 、a 2 、b 1 、b 2 、c 1 And c 2 For the to-be-determined fit coefficient, N represents the concentration.
4. A single silver powder computer color matching system for automotive metallic paint, comprising a computer system, characterized in that the computer system is programmed to perform the steps of the single silver powder computer color matching method for automotive metallic paint according to any one of claims 1 to 3.
5. A computer-readable medium, characterized in that: the computer-readable medium has stored thereon a computer program for causing a computer system to execute the steps of the single silver powder computer coloring method for automobile metallic paint according to any one of claims 1 to 3.
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| CN108875792A (en) * | 2018-05-25 | 2018-11-23 | 魔金真彩网络科技（长沙）有限公司 | A kind of coating based on machine learning repairs color method and system |
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| CN1692147A (en) * | 2002-12-10 | 2005-11-02 | 日本油漆株式会社 | Paint decision method, paint manufacturing method, coating method, paint decision server, and paint decision program |
| CN105787275A (en) * | 2016-02-29 | 2016-07-20 | 嘉兴学院 | Method for matching colors for leather dyeing by means of computer |
| CN107194081A (en) * | 2017-05-25 | 2017-09-22 | 魔金真彩网络科技（长沙）有限公司 | A kind of automobile plain color paint computer for colouring method |
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| CN1692147A (en) * | 2002-12-10 | 2005-11-02 | 日本油漆株式会社 | Paint decision method, paint manufacturing method, coating method, paint decision server, and paint decision program |
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Application publication date: 20180420 |