CN103576550A - Method for optimizing Yule-Nielsen modification values n based on spectroscopic data - Google Patents

Abstract

The invention discloses a method for optimizing Yule-Nielsen modification values n based on spectroscopic data. The ink formulas of selected detection samples are printed out, detection spectrums are measured, then a Neugebauer model modified by the built spectrum Yule-Nielsen is adopted to predicate the spectroscopic data of the ink formula of each detection sample according to different Yule-Nielsen modification values n lamda, then predication spectrums under the difference values n lamda are obtained, then the values RMSn lamda of the detection spectrums and the predication spectrums are calculated for a certain wave length, and the n lamda corresponding to the minimum RMSn lamda in the values RMSn lamda is selected as the optimal Yule-Nielsen modification value of the wave length lamda. The method is high in precision and simple in calculation and has high practical value.

Description

The optimization method of Yule-Nielsen modified value n based on spectroscopic data

Technical field

The present invention relates to a kind of optimization method of characterization model, specifically relate to the optimization method of a kind of Yule-Nielsen modified value n based on spectroscopic data.

Background technology

Printer is one of instrument conventional in people's routine work life, main output character and picture file.And the color of printer accurately reappears the extensive concern that is subject to industry member and academia as an important performance of printer, also deliver and published many relevant achievements in research.At present, about the color management of printer, mainly concentrate on the characterization model of printer, i.e. contact between apparatus for establishing color correlation space (as green grass or young crops, product, Huang, black ink consumption) and the equipment color independent space (as CIELAB value, spectroscopic data).The spectrum characterization method of printer mainly contains Colorimetric Characterization model and spectrum characterization model two classes.Colorimetric Characterization model utilizes CIELAB value as the equipment color independent space, have speed fast, calculate the features such as simple, but cannot avoid metamerism problem all the time; And spectrum characterization model is usingd the spectroscopic data of color as the equipment color independent space, precision is high and can effectively solve the problem of metamerism, although the method is calculated comparatively complicated, consuming time, the continuous lifting along with computer technology and performance, can significantly reduce computing time.

So far, spectrum Yule-Nielsen revises Neugebauer model and modified thereof are one of printer spectrum characterization models of commonly using the most.Yule-Nielsen modified value n is the important parameter of describing the optical dot gain of ink on paper, optimum Yule-Nielsen modified value n can reduce the predicated error of spectral model well, yet how to calculate optimized Yule-Nielsen modified value n, always is a difficult point.

Summary of the invention

The present invention, in order to solve the problem described in background technology, discloses the optimization method of a kind of Yule-Nielsen modified value n based on spectroscopic data, and its concrete steps are as follows:

1) for different application He Se districts, choose m ink set (each ink consumption), through the corresponding test samples of printer output;

2) utilize the spectroscopic data of each test samples of spectrophotometer measurement, must check spectrum R _{c, 1}(λ), R _{c, 2}(λ) ..., R _{c, m}(λ), wherein subscript C represents to check spectrum, and λ represents to measure wavelength, and subscript m represents m calibration sample;

3) for a certain wavelength X, Yule-Nielsen modified value n _λfrom 1 to 9 take 0.1 as interval, adopts the Neugebauer model of the spectrum Yule-Nielsen correction of having set up to predict the spectroscopic data of the ink set of each test samples, must be at different n _λprediction spectrum R under value _{p, n λ, 1}(λ), R _{p, n λ, 2}(λ) ..., R _{p, n λ, m}(λ), see following formula:

$R_{P,n_{\mathrm{\λ}}}\left(\mathrm{\λ}\right)={\left[\underset{i=1}{\overset{2^k}{\mathrm{\Σ}}}{w}_i{\left(R_i\left(\mathrm{\λ}\right)\right)}^{1/n_{\mathrm{\λ}}}\right]}^{n_{\mathrm{\λ}}}$

Wherein, R _{p, n λ}(λ) be the prediction spectrum of test samples ink set; K is the ink quantity that model adopts, and is generally 3 or 4; w _ibe the weight coefficient of each primary colours, can calculate according to the ink set of test samples; R _i(λ) be the spectroscopic data of each primary colours, when setting up the Neugebauer model of spectrum Yule-Nielsen correction, just measure; n _λit is the Yule-Nielsen modified value when wavelength X;

4), for a certain wavelength X, calculate different n _λprediction spectrum R under value _{p, n λ, 1}(λ), R _{p, n λ, 2}(λ) ..., R _{p, n λ, m}(λ) with corresponding check spectrum R _{c, 1}(λ), R _{c, 2}(λ) ..., R _{c, m}(λ) RMS between _{n λ}value, see following formula:

${\mathrm{RMS}}_{n_{\mathrm{\λ}}}=\sqrt{\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{(R_{C,i}\left(\mathrm{\λ}\right)-R_{P,\mathrm{n\λ},i}\left(\mathrm{\λ}\right))}^2}{m}}$

5) for a certain wavelength X, from different n _λrMS under value _{n λ}in value, select that minimum RMS _{n λ}corresponding n _λoptimum Yule-Nielsen modified value as wavelength X.

The present invention exports and measures and to obtain check spectrum by the ink set of the test samples of choosing is printed, afterwards according to different Yule-Nielsen modified value n _λ, adopt the Neugebauer model of the spectrum Yule-Nielsen correction of having set up to predict and obtain different n the spectroscopic data of the ink set of each test samples _λprediction spectrum under value, then for a certain wavelength, calculates different n _λcheck spectrum under value and the RMS that predicts spectrum _{n λ}value, therefrom chooses RMS _{n λ}that RMS that value is minimum _{n λ}corresponding n _λoptimum Yule-Nielsen modified value as wavelength X.This invention precision is high, calculates simply, has very high practical value.

Accompanying drawing explanation

Fig. 1 is the optimization method of the Yule-Nielsen modified value n based on spectroscopic data;

Different n when Fig. 2 is embodiment medium wavelength 400nm ₄₀₀rMS under value _n400value;

Fig. 3 is the optimum Yule-Nielsen modified value n under different wave length in embodiment _λ;

Embodiment

The Neugebauer model that the spectrum Yule-Nielsen of a green grass or young crops, product, Huang, black four black printers of take revises is example, and the optimization method of the above-mentioned Yule-Nielsen modified value n based on spectroscopic data is set forth.As shown in Figure 1, its concrete steps are as follows:

1) choose 100 ink sets (each ink consumption), the different colours that comprises each look district, through the corresponding test samples of printer output;

2) utilize the spectroscopic data of each test samples of spectrophotometer measurement, must check spectrum R _{c, 1}(λ), R _{c, 2}(λ) ..., R _{c, m}(λ), wherein subscript C represents to check spectrum, and λ represents to measure wavelength, and subscript m represents m calibration sample, spectral measurement ranges be 400nm to 700nm, take 10nm as interval;

3) for wavelength 400nm, Yule-Nielsen modified value n ₄₀₀from 1 to 9 take 0.1 as interval, adopts the Neugebauer model of the spectrum Yule-Nielsen correction of having set up to predict the spectroscopic data of the ink set of each test samples, must be at different n ₄₀₀prediction spectrum R under value _{p, n400,1}(400), R _{p, n400,2}(400) ..., R _{p, n400, m}(400), see following formula:

$R_{P,n_{400}}\left(400\right)={\left[\underset{i=1}{\overset{2^4=16}{\mathrm{\&Sigma;}}}{w}_i{\left(R_i\left(400\right)\right)}^{1/n_{400}}\right]}^{{\mathrm{<figure-callout\; id="400"\; label="n"\; filenames="HSA00000875755600022.png"\; state="\{\{state\}\}">n</figure-callout>}}_{400}}$

4), for wavelength 400nm, calculate different n ₄₀₀prediction spectrum R under value _{p, n400,1}(400), R _{p, n400,2}(400) ..., R _{p, n400, m}(400) with corresponding check spectrum R _{c, 1}(400), R _{c, 2}(400) ..., R _{c, m}(400) RMS between _n400value, see following formula:

${\mathrm{<figure-callout\; id="400"\; label="RMS\; n"\; filenames="HSA00000875755600022.png"\; state="\{\{state\}\}">RMS</figure-callout>}}_{n_{}}=\sqrt{\frac{\underset{i=1}{\overset{100}{\mathrm{\&Sigma;}}}{(R_{C,i}\left(400\right)-R_{P,\mathrm{<figure-callout\; id="400"\; label="n"\; filenames="HSA00000875755600022.png"\; state="\{\{state\}\}">n</figure-callout>}400,i}\left(400\right))}^2}{100}}$

5) for wavelength 400nm, from different n ₄₀₀rMS under value _{n λ}in value, select that minimum RMS _{n λ}corresponding n ₄₀₀as the optimum Yule-Nielsen modified value of wavelength X, see Fig. 2;

6) for other wavelength, can repeating step 3)-5) calculate corresponding optimum Yule-Nielsen modified value n _λ, see Fig. 3.

Claims (5)

1. an optimization method of the Yule-Nielsen modified value n based on spectroscopic data, is characterized in that comprising the following steps:

1) for different application He Se districts, choose m ink set (each ink consumption), through the corresponding test samples of printer output;

2) utilize the spectroscopic data of each test samples of spectrophotometer measurement, must check spectrum R _{c, 1}(λ), R _{c, 2}(λ) ..., R _{c, m}(λ), wherein subscript C represents to check spectrum, and λ represents to measure wavelength, and subscript m represents m calibration sample;

3) for a certain wavelength X, Yule-Nielsen modified value n _λfrom 1 to 9 take 0.1 as interval, adopts the Neugebauer model of the spectrum Yule-Nielsen correction of having set up to predict the spectroscopic data of the ink set of each test samples, must be at different n _λprediction spectrum R under value _{p, n λ, 1}(λ), R _{p, n λ, 2}(λ) ..., R _{p, n λ, m}(λ), see following formula:

$R_{P,n_{\mathrm{\&lambda;}}}\left(\mathrm{\&lambda;}\right)={\left[\underset{i=1}{\overset{2^k}{\mathrm{\&Sigma;}}}{w}_i{\left(R_i\left(\mathrm{\&lambda;}\right)\right)}^{1/n_{\mathrm{\&lambda;}}}\right]}^{n_{\mathrm{\&lambda;}}}$

Wherein, R _{p, n λ}(λ) be the prediction spectrum of test samples ink set; K is the ink quantity that model adopts, and is generally 3 or 4; w _ibe the weight coefficient of each primary colours, can calculate according to the ink set of test samples; R _i(λ) be the spectroscopic data of each primary colours, when setting up the Neugebauer model of spectrum Yule-Nielsen correction, just measure; n _λit is the Yule-Nielsen modified value when wavelength X;

4), for a certain wavelength X, calculate different n _λprediction spectrum R under value _{p, n λ, 1}(λ), R _{p, n λ, 2}(λ) ..., R _{p, n λ, m}(λ) with corresponding check spectrum R _{c, 1}(λ), R _{c, 2}(λ) ..., R _{c, m}(λ) RMS between _{n λ}value, see following formula:

${\mathrm{RMS}}_{n_{\mathrm{\&lambda;}}}=\sqrt{\frac{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{(R_{C,i}\left(\mathrm{\&lambda;}\right)-R_{P,\mathrm{n\&lambda;},i}\left(\mathrm{\&lambda;}\right))}^2}{m}}$

5) for a certain wavelength X, from different n _λrMS under value _{n λ}in value, select that minimum RMS _{n λ}corresponding n _λoptimum Yule-Nielsen modified value as wavelength X.

2. the optimization method of the Yule-Nielsen modified value n based on spectroscopic data according to claim 1, is characterized in that described step 1) in for different application He Se districts, choose m ink set, through the corresponding test samples of printer output.Wherein, m is generally about 100, if desired increases especially the precision in certain district of the same colour, can increase the test samples quantity in that district of the same colour.

3. the optimization method of the Yule-Nielsen modified value n based on spectroscopic data according to claim 1, is characterized in that described step 3) for a certain wavelength X, Yule-Nielsen modified value n _λfrom 1 to 9 take 0.1 as interval, adopts the Neugebauer model of the spectrum Yule-Nielsen correction of having set up to predict the spectroscopic data of the ink set of each test samples, must be at different n _λprediction spectrum under value.N wherein _λspan and interval can adjust as required, general optimal value is within l to 9, but span is larger, interval is less, precision is higher, and computing velocity is slower.

4. the optimization method of the Yule-Nielsen modified value n based on spectroscopic data according to claim 1, is characterized in that described step 4) in for a certain wavelength X, calculate different n _λprediction spectrum under value and the corresponding RMS checking between spectrum _{n λ}value.

5. the optimization method of the Yule-Nielsen modified value n based on spectroscopic data according to claim 1, is characterized in that described step 5) in for a certain wavelength X, from different n _λrMS under value _{n λ}in value, select that minimum RMS _{n λ}corresponding n _λoptimum Yule-Nielsen modified value as wavelength X.

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