Embodiment two
The present embodiment does further supplementary explanation to the determination method for the printing equipment linearization curve that embodiment one provides.
As a kind of enforceable mode, on the basis of the above embodiment 1, optionally, step 101 specifically be can wrap
It includes:
Step 2011, step-wedge color target figure is obtained according to default input point set.
Step 2012, the step-wedge measurement density and step-wedge maximum for obtaining step-wedge color target figure measure density.
Step 2013, density and preset multiple Nelson's coefficients are measured according to step-wedge maximum, obtains corresponding standard ginseng
Examine density.
Corresponding canonical reference density is specifically obtained using following formula (1):
Wherein, DsDensity is measured for step-wedge maximum, N is Nelson's coefficient, XiIt represents in default input point set In i-th
The value of input point, DiRepresent the value X of i-th of input point in default input point set IniCorresponding canonical reference density value.
Step 2014, density is measured according to step-wedge and each Nelson's coefficient of canonical reference density fitting acquisition is corresponding alternative
Linearization curve.
As another enforceable mode, on the basis of the above embodiment 1, optionally, step 104 specifically can be with
Include:
Step 2021, according to the measurement density data of each tertiary colour target figure, three color field survey density datas, and it is default
The corresponding printing standard density data of sampling point set determines the calculating standard density of each point in default sampling point set.
Step 2022, corresponding with default sampling point set compound according to the calculating standard density of each point in default sampling point set
The measurement density data of color target figure determines the mean difference of each point in the corresponding each default sampling point set of each alternative linearization curve
Ratio.
Step 2023, according to the mean difference ratio of each point in the corresponding each default sampling point set of each alternative linearization curve
Rate determines target Nelson's coefficient.
Optionally, step 2021 can specifically include:
Step 2031, the default corresponding printing standard density data of sampling point set is obtained.
Step 2032, the ratio between three color field survey density and printing standard density curve vertex density is calculated.
Step 2033, according to the ratio between three color field survey density and printing standard density curve vertex density, really
Surely the calculating standard density of each point in default sampling point set.
Specifically, inputting point set InS and printing standard density curve according to printing standard density curve, printing mark is obtained
Quasi- density data OutS, presetting sampling point set is n point for selecting to obtain from InS, is denoted as set InD;
The default corresponding printing standard density data of sampling point set is obtained from OutS;
(3) calculate the ratio between three color field survey density and printing standard density curve vertex density according to the following formula
Rate:
Rate=(OutMIt is real-OutSzq)/(OutSjq-OutSzq)z,j∈[2,r-1]OutSzq≤OutMIt is real≤OutSjq
(3);
Wherein: OutMIt is realFor tri- color field survey density of CMY;OutSjqAnd OutSzqFor printing standard density curve set
The vertex density of jth and z curve in OutS, wherein z=j-1;
According to the ratio between three color field survey density and printing standard density curve vertex density, using following formula
(4) the calculating standard density Std of each point in default sampling point set is calculated:
Wherein, t represent in point set InS with i-th of point value Z in default sampling point set InDiIt is worth the call number of corresponding point,
OutSjt、OutSztIndicate the printing mark of jth and z printing standard density points concentration t point in printing standard density data set OutS
The relationship of quasi- density value, z and j are as follows: z=j-1.
Optionally, step 2022 can specifically include:
Step 2041, corresponding with default sampling point set compound according to the calculating standard density of each point in default sampling point set
The measurement density data of color target figure calculates the difference ratio of each point in default sampling point set.
Specifically, being directed to every alternative linearization curve, the calculating standard density and symbol of default sampling point set can be all corresponded to
The measurement density data of color target figure is closed, therefore, the difference ratio for calculating acquisition also has multiple groups, every group of correspondence one alternative linearisation
Curve.
Step 2042, it according to the difference ratio of each point in default sampling point set, calculates and obtains each alternative linearization curve pair
The mean difference ratio answered.
Specifically, according to the calculating standard density tertiary colour corresponding with default sampling point set of each point in default sampling point set
The measurement density data of target figure calculates the difference ratio △ E of each point in default sampling point set using following formula (5)i:
△Ei=fabs (Stdi-OutMji)/Stdii∈[1,n] (5);
Wherein: StdiFor the calculating standard density for presetting each point in sampling point set InD, OutMjiFor in OutMj and in InD
The corresponding measurement density of point i, n indicate the number of sampled point in default sampling point set;
(6) obtain the corresponding mean difference ratio △ E of each Nelson's coefficient according to the following formulameanj:
△Emeanj=(△ E1+…△Ei+…+△En)/n i∈[1,n] (6)。
Wherein, △ EmeanjIndicate the corresponding mean difference ratio of j-th of Nelson's coefficient.
Optionally, step 2023 can specifically include: will be worth Nelson's coefficient corresponding to the smallest mean difference ratio
It is determined as target Nelson's coefficient.
Specifically, the smallest Nelson's coefficient of mean difference ratio is target Nelson's coefficient.Target Nelson system
The corresponding alternative linearization curve of number is target linearization curve.
The determination method of printing equipment linearization curve provided in this embodiment, it is linear for equipment in printing color management
The demand of change, be based on printing standard density curve, from the corresponding alternative linearization curve of a plurality of Nelson's coefficient choose to
The most matched target linearization curve of printing standard density curve, realizes Nelson's coefficient value and automatically determines, it is ensured that generation
Target linearization curve meets printing standard, is into one to achieve the purpose that science, accurate generating device linearization curve
The color management of step lays the foundation.A plurality of linearization curve is generated using traversal Nelson's Y-factor method Y, exports a variety of different contrasts
Then the sampled point tertiary colour target of level calculates sampled point using tri- color field survey density of CMY in conjunction with printing standard density
Standard density chooses optimal Nelson's coefficient value by calculating sampled point standard density and measuring the difference ratio of density.Wherein
The output effect of variant Nelson's coefficient value can be known in advance in traversal;The standard density of sampled point is close according to printing standard
Degree calculates, and is more in line with printing standard specification, and the equipment after capable of guaranteeing calibration meets the standard of printing, and it is color to reach control
The purpose of chromatic graph picture entirety contrast.
Embodiment three
The present embodiment does further specifically the determination method of printing equipment linearization curve provided by the above embodiment
It is bright.
This method can specifically include following four step:
Step 1: obtaining the corresponding a plurality of linearization curve of multiple Nelson's coefficients
K printing equipment linearization curve of setting is indicated by following expressions:
In={ X1,X2,......,Xi,......,Xm} Xi∈[0,100]
Out={ Out1,Out2,......,Outj,......,Outk} j∈[1,k]
Outj={ Y1,Y2,......,Yi,......,Ym} Yi∈[0,100]
Wherein: In indicates input point set (unit is percentage), and m indicates In number, XiRepresent the value of input point;Out
Indicate that k linearization curve exports point set;OutjIndicate that j-th strip equipment linearization curve exports point set, YiRepresent j-th strip
X in linearization curveiCorresponding output valve.
The process for specifically obtaining above-mentioned k linearization curve is as follows:
(1) step-wedge color target figure is printed
Step-wedge color target figure is made of the step-wedge of each color of printing device, and the color value in step-wedge is by m in point set In
Sample color lump composition.
(2) measurement step-wedge color target figure obtains step-wedge and measures density
The assorted face step-wedge measurement density curve of output indicates that assorted face step-wedge measures density points with point set In and D'
Set D' is expressed as follows:
D'={ D'1, D'2..., D'i..., D'm, i ∈ [1, m]
Wherein, D'iRepresent X in point set IniCorresponding step-wedge measures density value.
Step-wedge color target figure is measured, assorted face step-wedge measurement density point set D' is obtained and assorted face step-wedge maximum measures density
Ds。
(3) canonical reference density is calculated according to maximum measurement density and preset multiple Nelson's coefficients
Single canonical reference density curve data can indicate that point set D is expressed as follows with point set In and D:
D={ D1, D2..., Di..., Dm, i ∈ [1, m]
Wherein, DiRepresent X in point set IniCorresponding canonical reference density value.
DiIt is calculated and is obtained by following formula (1):
Wherein, DsThe assorted face step-wedge maximum obtained for above-mentioned measurement measures density, and N is Nelson's coefficient.
Multiple Nelson's coefficients are preset, for example Nelson's coefficient N is taken as:
A plurality of canonical reference density output valve is calculated according to formula (1), canonical reference density output valve point set indicates
It is as follows:
Wherein, Dj represents the corresponding canonical reference density set of j-th of printing equipment color face Nelson's coefficient value.
(4) fitting obtains k linearization curve
Density data D' and j-th strip canonical reference density set Dj fitting, which is measured, according to step-wedge obtains linearization curve Oj。
The specific following formula of fitting formula (2):
Wherein, YiThe j-th strip linearization curve data as acquired;
DjiIt represents j-th strip reference density point and concentrates XiCorresponding reference density value, D'pAnd D'p-1Respectively indicate input point set
Close X in InpAnd Xp-1Corresponding step-wedge measures density value;
The value of i and p meets following relationship:
D'p≤Dji≤D'p-1。
Step 2: using a plurality of spare linearisation curve printing tertiary colour target figure obtained
After obtaining the spare linearization curve of k item, then the spare linearisation curve printing tertiary colour target figure of the k item, tool are used
Body process is as follows:
Printing standard density curve input point set is set as lnS (for known standard point set):
InS={ S1,S2,......,Si,......,Sq} Si∈[0,100]
Wherein: SiIndicate input point value (unit is percentage), q indicates the number of input point.
Standard input point set lnS corresponds to the output point set of r different vertex densities, and being generally denoted as OutS (is known
International standard), it is expressed as follows:
OutS=OutS1, OutS2 ..., OutSj ..., OutSr } j ∈ [1, r]
Wherein: r is the quantity of printing standard density curve, and q is the number of the output point of each printing standard density curve,
OutSj represents print of the printing standard density curve input point set InS under the vertex density of j-th strip printing standard density curve
Brush standard density set;OutSjiRepresent i-th of input point value S in point set InSiIt is close on j-th strip printing standard density curve vertex
The respective value under point set OutSj is spent, presetting sampled point is the n point selected from point set InS, and default sampled point is denoted as InD.
(1) Samples selecting is preset
It selects n point as default sampled point from printing standard density curve input point set lnS, is denoted as default sampling
Point set InD, is expressed as follows:
InD={ Z1,Z2,......,Zi,......,Zn} Zi∈[0,100]
Wherein, ZiThe CMY input value (unit is percentage) of each sampled point is represented, n represents default number of sampling points.
(2) tertiary colour target figure is printed
Using input tri- color of point set InD and CMY on the spot color lump (i.e. tri- color value of CMY be 100 color lump) formulate output
Color target figure.
The tertiary colour target figure is exported with the alternative linearization curve of k item of above-mentioned acquisition and is measured, and measurement density number is obtained
According to tri- color field survey density value OutM of set OutM and CMYIt is real.OutM is expressed as follows:
OutM=OutM1, OutM2 ..., OutMj ... OutMk } j ∈ [1, k]
Wherein: OutMj represents the corresponding measurement density set of default sampled point of different alternative linearization curve outputs;
OutMjiRepresent Z in default sampling point set InDiRespective value at OutMj.
Step 3: calculating the calculating standard density of default sampling point set
The default corresponding calculating standard density of sampling point set InD is calculated, detailed process is as follows:
(1) density ratio calculates
It is calculated between tri- color field survey density of CMY and printing standard density curve vertex density using following formula (3)
Ratio:
Rate=(OutMIt is real-OutSzq)/(OutSjq-OutSzq)z,j∈[2,r-1] OutSzq≤OutMIt is real≤OutSjq
(3)
Wherein: OutMIt is realFor tri- color field survey density of CMY, i.e., three color field survey density of above-mentioned acquisition;
OutSjqAnd OutSzqFor the vertex density of jth and z curve in printing standard density curve set OutS, wherein z
=j-1.
(2) the calculating standard density of default sampling point set is determined according to ratio
If the default corresponding calculating standard density of sampling point set InD is denoted as point set Std:
Std={ Std1,Std2,...,Stdi,...Stdn} i∈[1,n]
Wherein: StdiRepresent Z in default sampling point set InDiCorresponding calculating standard density value, StdiIt calculates using as follows
Formula (4):
Wherein: t represent in point set InS with Z in default sampling point set InDiIt is worth corresponding inode number, OutSjt、
OutSztIndicate that jth and z printing standard density points concentrate the printing standard of t node close in printing standard density curve set OutS
The relationship of angle value, z and j are as follows: z=j-1.
Step 4: Nelson's coefficient is chosen
This step mainly chooses Buddhist nun by calculating sampled point calculating standard density and measuring the difference ratio between density
Ademilson coefficient value.
(1) calculating difference ratio
It calculates the default corresponding calculating standard density set Std of sampling point set InD and a certain item measures density set OutMj
Between each point mean difference ratio.
Single node difference ratio △ E is calculated according to following formula (5)i:
△Ei=fabs (Stdi-OutMji)/Stdi i∈[1,n] (5)
Wherein: StdiFor the calculating standard density of each node of InD, OutMjiFor the corresponding measurement of each node i of InD in OutMj
Density, n indicate sampling number.
By the above-mentioned density difference ratio △ E being calculatedi(6) are averaged to obtain △ E according to the following formulameanj。
△Emeanj=(△ E1+…△Ei+…+△En)/n i∈[1,n] (6)
(2) Nelson's coefficient value is determined
K linearization curve is calculated separately according to the method described above and corresponds to each node mean difference ratio, is denoted as set △
Emean:
△Emean={ △ Emean1,△Emean2,...,△Emeanj,...,△Emeank} j∈[1,k]
Assuming that set △ EmeanMiddle minimum value is △ Emeanj, then the corresponding Nelson's coefficient value of the difference ratio is and seeks
Nelson's coefficient.
Illustratively, in the present embodiment, the output equipment used for 7910 digital-code printer of EPSON Stylus Pro,
Paper is general too gram 170 grams of advanced matt photo papers, and measuring device is the EyeOne-iSis of X. Rite Inc..Optionally, may be used
To be other enforceable output equipment, paper or measuring devices, the present embodiment is only exemplary explanation, not limits it
System.
The number of input point is set as m=30, input point set is preset and uses following data:
In=0.0,1.0,2.0,3.0,4.0,6.0,8.0,10.O, 12.0,15.0,17.0,20.0,24.0,28.0,
32.0,36.0,40.0,44.0,48.0,52.0,56.0,61.0,65.0,70.0,75.0,80.0,85.0,90.0,95.0,
100.0}
Firstly, printing step-wedge color target figure, color target figure is by tetra- color face ladders of C, M, Y, K using above-mentioned default input point set
Ruler composition, as shown in table 1:
Table 1
Cyan face node C |
C1 |
C2 |
C3 |
… |
C28 |
C29 |
C30 |
Product color face node M |
M1 |
M2 |
M3 |
… |
M28 |
M29 |
M30 |
Yellow face node Y |
Y1 |
Y2 |
Y3 |
… |
Y28 |
Y29 |
Y30 |
Black side node K |
K1 |
K2 |
K3 |
… |
K28 |
K29 |
K30 |
The color lump figure successively printed using the assorted printing ink of above-mentioned default input point ratio, specially existing skill
Art, details are not described herein.
With each color lump of measuring instrument measurement step-wedge color target figure, the step-wedge for obtaining each color lump in assorted face measures density point set
It closes D' and assorted face step-wedge maximum measures density Ds。
D'={ D'1, D'2..., D'i..., D'30, i ∈ [1,30]
For example, the step-wedge maximum measurement density in the tetra- color faces C, M, Y, the K obtained in the present embodiment be respectively 1.72,
1.73,1.22 and 1.74.
Optionally, after obtaining step-wedge maximum measurement density according to measurement, maximal density can also be rule of thumb set, then
The step-wedge maximum measurement density D finally usedsIt is obtained for measurement and smaller in the two is arranged in experience, for example be rule of thumb arranged
Step-wedge maximal density be respectively 1.80,1.80,1.10,1.80, then the step-wedge maximum that finally uses measurement density DsFor 1.72,
173、1.10、1.74。
Density D is measured with the step-wedge maximum in a color face belowsFor, illustrate the target linearisation song for a colour system
The determination process of line.The specific determination process of other each colour systems is identical as the colour system, the step-wedge maximum measurement density only used
It is different.
25 Nelson's coefficients are preset in the present embodiment, as follows:
The previously obtained step-wedge maximum finally used is measured density Ds, such as the step-wedge maximum measurement density D of cyan Cs
Formula (1) is substituted into respectively for 1.72 and 25 Nelson's coefficient values, and canonical reference density point set D is calculated.
Wherein, Dj represents the corresponding canonical reference density set of j-th of printing equipment color face Nelson's coefficient value.That is D
Include the corresponding canonical reference density set of 25 Nelson's coefficients, include in each canonical reference density set 30 with it is pre-
If the corresponding canonical reference density of 30 input points that input point is concentrated.
Each Dj in canonical reference density D and measurement density data D' are substituted into above-mentioned formula (2) respectively, obtain 25 groups of outputs
Point set Out:
Out={ Out1,Out2,......,Outj,......,Out25} j∈[1,25]
Outj={ Y1,Y2,......,Yi,......,Y30} Yi∈[0,100]
25 alternative linearization curves are obtained according to default input point set In and output point set Out fitting.
It includes q=25 standard sample point in point set InS that printing standard density curve standard, which inputs, as follows:
InS=(0,0,0), (2,1,1), (4,3,3), (6,4,4), (8,5,5), (10,7,7), (15,11,11),
(20,15,15),(25,19,19),(30,23,23),(35,27,27),(40,31,31),(45,36,36),(50,40,40),
(55,45,45),(60,50,50),(65,55,55),(70,60,60),(75,66,66),(80,72,72),(85,78,78),
(90,84,84),(95,92,92),(98,97,97),(100,100,100)}
Bloom, shadow, each point of middle tone are selected from printing standard density curve input point set lnS, as default
Sampling point set InD, it may be assumed that
InD={ (25,19,19), (50,40,40), (75,66,66) }
Using default sampling point set InD and tri- color of CMY, color lump (100,100,100) formulates output tertiary colour target figure on the spot,
It is as shown in table 2:
Table 2
Wherein InD25, InD50, InD75 respectively indicate color lump dot percentage CMY (25,19,19), CMY (50,40,
40) and CMY (75,66,66), N0.5 indicate that the color lump is exported using the corresponding linearization curve of Nelson's coefficient value 0.5;
CMY100 indicates tri- color of CMY color lump on the spot.
The tertiary colour target figure is exported using 25 alternative linearization curves of above-mentioned acquisition and is measured, and measurement density number is obtained
According to tri- color field survey density value OutM of set OutM and CMYIt is real。
For example, the three color field survey density OutM that the present embodiment obtainsIt is realIt is 1.95.
Corresponding OutS (the printing standard that the present embodiment uses of standard input point set InS of printing standard density curve
Density curve includes 20 curves, i.e. r=20) are as follows:
It is the point in InS due to presetting each point in sampling point set InD, inputting the default sampling point set of point set according to standard can
To learn, (25,19,19), (50,40,40) and (75,66,66) in default sampling point set InD respectively correspond S in InS9、S14
And S19.That is InD corresponds to the OutSj in the OutSj in OutS9、OutSj14And OutSj19, j ∈ [1,20].
According to tri- color field survey density of the corresponding printing standard density of InD and the CMY of above-mentioned acquisition, using formula (3)
Calculate the ratio between tri- color field survey density of CMY and printing standard density curve vertex density.Printing standard density curve
Vertex density is OutSj25。
Rate=(OutMIt is real-OutSz25)/(OutSj25-OutSz25)z,j∈[2,r-1] OutSz25≤OutMIt is real≤
OutSj25 (3)
Wherein, z=j-1.
For example, three color field survey density OutMIt is realIt is 1.5, the vertex density point of two adjacent printing standard density curves
It Wei not 1.4 and 1.7, i.e. OutSz25It is 1.4, OutSj25It is 1.7, then three color field survey density and printing standard density curve
Ratio between vertex density are as follows:
Rate=(OutMIt is real-OutSz25)/(OutSj25-OutSz25)=(1.5-1.4)/(1.7-1.5)=0.5 z, j ∈
[2,r-1]
Then preset Z in sampling point set InDiCorresponding calculating standard density value StdiIt can be determined using formula (4).That is,
Due to OutSz25≤OutMIt is real≤OutSj25: it can be obtained according to formula (4):
Stdi=rate*OutSjt+(1-rate)*OutSzt
For each point (25,19,19), (50,40,40) and (75,66,66) in InD, corresponding calculating standard
Density is respectively as follows:
Std1=rate*OutSj9+(1-rate)*OutSz9
Std2=rate*OutSj14+(1-rate)*OutSz14
Std3=rate*OutSj19+(1-rate)*OutSz19。
If OutMIt is real≤OutS125, then:
Std1=OutS19
Std2=OutS114
Std3=OutS119。
If OutMIt is real≥OutS2025, then
Std1=OutS209
Std2=OutS2014
Std3=OutS2019。
For example, the corresponding calculating standard density of each point is respectively in the default sampling point set InD that the present embodiment determines
0.255,0.540,0.980.
In default sampling point set InD has been determined after the corresponding calculating standard density of each point, default sampling is further determined that
Each point mean difference ratio between the corresponding calculating standard density set Std of point set InD and a certain item measurement density set OutMj
△Emeanj, i.e. the corresponding mean difference ratio of j-th of Nelson's coefficient or the alternative linearization curve of j-th strip are corresponding average
Difference ratio.
△E1=fabs (Std1-OutMj1)/Std1
△E2=fabs (Std2-OutMj2)/Std2
△E3=fabs (Std3-OutMj3)/Std3
△Emeanj=(△ E1+△E2+△E3)/3。
The corresponding mean difference ratio set △ of the alternative linearization curve of acquisition 25 is calculated separately according to the method described above
Emean, it may be assumed that
△Emean={ △ Emean1,△Emean2,...,△Emeanj,...,△Emean25} j∈[1,25]
It is the mean difference ratio that the present embodiment obtains as shown in table (3):
Table 3
If set △ EmeanMiddle minimum value is △ Emeanj, then the corresponding Nelson's coefficient of the mean difference ratio is target
Nelson's coefficient.Namely the corresponding alternative linearization curve of target Nelson's coefficient is target linearization curve.Such as 2 institute of table
Show, it is known that, mean difference ratio minimum 0.055, corresponding Nelson's coefficient is 1.3, then Nelson's coefficient 1.3 is corresponding
Alternative linearization curve is the corresponding target linearization curve of the colour system.
The above are the corresponding target linearization curves of cyan determined using cyan system step-wedge maximum measurement density Ds, simultaneously
Its corresponding target linearization curve can also be determined using the step-wedge maximum measurement density of other colour systems.Detailed process and cyan
Process is identical, and details are not described herein.
The determination method of printing equipment linearization curve provided in this embodiment, it is linear for equipment in printing color management
The demand of change, be based on printing standard density curve, from the corresponding alternative linearization curve of a plurality of Nelson's coefficient choose to
The most matched target linearization curve of printing standard density curve, realizes Nelson's coefficient value and automatically determines, it is ensured that generation
Target linearization curve meets printing standard, is into one to achieve the purpose that science, accurate generating device linearization curve
The color management of step lays the foundation.A plurality of linearization curve is generated using traversal Nelson's Y-factor method Y, exports a variety of different contrasts
Then the sampled point tertiary colour target of level calculates sampled point using tri- color field survey density of CMY in conjunction with printing standard density
Standard density chooses optimal Nelson's coefficient value by calculating sampled point standard density and measuring the difference ratio of density.Wherein
The output effect of variant Nelson's coefficient value can be known in advance in traversal;The standard density of sampled point is close according to printing standard
Degree calculates, and is more in line with printing standard specification, and the equipment after capable of guaranteeing calibration meets the standard of printing, and it is color to reach control
The purpose of chromatic graph picture entirety contrast.