CN1065738A - The establishing method of curve of grey-board used in multi-colour plate-making - Google Patents
The establishing method of curve of grey-board used in multi-colour plate-making Download PDFInfo
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Abstract
The present invention is the establishing method of curve of grey-board used in multi-colour plate-making.In order to replace " concentration value " in the past now to utilize the concentration family curve of taking pictures of the light reaching the film material of color photographic original copy, " light value " obtained picture information value as original image, utilize specific gray shade scale transformation curve that it is handled, obtain version (C.M.Y) color separation curve of all kinds.Then, be benchmark with this look version color separation curve, decision adds black scope, simultaneously, utilizes the same gray shade scale transform that is adopted when setting version of all kinds (C.M.Y) with the look curve to set the color separation curve of China ink version (B) usefulness.
Description
The present invention relates to and polychrome plate-making the reasonable establishing method of the China ink version (the following B version that also claims) that promptly blue version, red version, yellow version (following C, M, the Y version of also claiming) are used in combination.
In more detail, the invention provides a kind of like this new method, be the standard color separation curve of C version etc. yes according to the relation of these standard colors versions, decide according to specific gray shade scale transform (image information of Continuous Gray Scale is transformed into the used relational expression of dot area % value), the color separation curve of B version usefulness also is so reasonably to set.
In the past, extensively be familiar with by people in the importance of polychrome plate-making China and Mexico's versions (B version).For example the status of B version has been acknowledged as and has finally mixed up color printing image gray scale and the necessary important version of tone.
As everyone knows, the color separation operation is made up of two parts, and a part of operation is the site gray shade scale that the image information value of Continuous Gray Scale grade original image (concentration information value or the physical quantity relevant with it) is transformed into printed images; Another part operation is colour correction.Particularly nearest, owing to original image will equally with literal duplicate truly, and reproduce original tone, so, preceding a kind of operation, i.e. the importance of greyscale transformation technology (tone rendering) more and more is subject to people's attention.Because when making printing image, if the delicate trickle tone (gray scale) that original image had is in case destroyed, what colour correction technology that don't work remedies, and can not copy disrupted original tone, so people pay attention to the greyscale transformation technology result that is inevitable.But for a long time, in the industry, the viewpoint that colour correction is placed above the other things extremely makes still to the very strong dominating role that is manufactured with of printed matter, also is subjected to the harmful effect of above-mentioned viewpoint as the scanner (colour esensitized equipment) of color separation power tool.
In a word, above-mentioned greyscale transformation operation is that operation or work standard is carried out with the color separation curve.So-called color separation curve is meant the curve that the normal coordinates of concentration value (horizontal ordinate) with original image and dot area % value (ordinate) are represented, be the epochmaking curve of regulation greyscale transformation (Continuous Gray Scale is transformed into the site gray scale), also can be described as gray-scale rendition curve, tone reproduction curves.
Polychrome plate-making is to carry out according to the color separation curve to various look versions (C, M, Y) and China ink version (B) defined respectively.Wherein, China ink version (B) can be used for polychrome plate-making by following method.
(1) the trichromatic system version of version of all kinds (C, M, Y), because printing ink is impure, promptly the spectral reflectance rate curve of printing ink departs from perfect condition far away, so can not produce black.Mainly be to adopt China ink version (B) in order to compensate this error.
(2) moreover, China ink version (B) be since with the undercolour removal UCR(Under Color Removal that scans 1) technology is relevant adopts.
The relation of above-mentioned undercolour removal UCR and black version (B) is for the gray balance maintenance of shadow (shade) balance adjustment (blackness, photographic fog, the concentration adjustment of shade part), medium tone or the whole district, prints the reduction of adaptation (printing high speed, the adjustment of ink setting time), printing ink cost etc., use B version when reducing a part of look version (C, M, Y) (removal background color).
The user mode of B version can be according to beginning to add (this is called starting point STP) from much concentration to version of all kinds in the industry, and add much amounts (UCR) amount) etc. situation distinguished.The former STP is called short distance, and for example, be called " skeleton " that the concentration since 10 adds (Skeleton) deceives; Begin to add the highlight of China ink version (B) from the low concentration identical, be called complete blackly with the look version.This uses as key plate in achromatism plate-making.The latter's the complete black GCR(Gray Component Rep-lacement that is called: the displacement of grey composition), adopt " achromatism color dub " this term in Europe.In these B versions,, and whether printed matter to be processed into viewpoints such as soft or vigour and this color separation curve suitably be changed by scan operation person or other people according to above-mentioned viewpoint.
The problem that in the setting of above-mentioned color separation curve, exists have following some.Be that the color separation curve of version of all kinds (C, M, Y) in original technology will adopt the curve of setting by scan operation person's experience and sensation, perhaps adopt by the makers' experience of scanner and set and be stored in curve in the scanner storage portion.
On the other hand, the color separation curve of China ink version (B) the outstanding version of reflection (C, M, a Y) is in above-mentioned state with color separation curve, this color separation curve also be main by rule of thumb.Can not satisfy the demand far away from the above-mentioned curve of this viewpoint of color separation curve of reasonably setting look version and China ink version.
The reasonable viewpoint of setting about above-mentioned look version (C, M, Y) and China ink version (B) color separation curve is: the high light of the H(of original image portion)～5(shade portion) the concentration scale of each pixel to be reproduced in 1: 1 validity on the printed images, in other words, after the conversion of original image information process gray shade scale, obtain to make people's vision to feel very natural concentration scale, should consider organic relation between each edition according to this viewpoint, set the color separation curve of various version usefulness.
Certainly, when setting the color separation curve of China ink version (B) usefulness, seeking the plan reasonable method still has very big difficulty.This difficulty is the arrangement architecture of fine site.
The following describes especially in the cancellation of UCR(background color) or GCR(grey composition displacement) the problems referred to above of occurring when setting the color separation curve of China ink version (B) usefulness under the condition.
In order rationally to set color separation curve, the color separation curve of China ink version (B) usefulness should be set the various look versions (C, M, Y) of carrying out the background color elimination through the B version and use color separation curve simultaneously because C, M, the overlapping grey that produces of three kinds of printing-inks of Y and/or black content are set as basic.In the case, as C, M, when three kinds of printing-inks of Y are overlapping, in the whole zone of the H of color printing image portion～S portion, under what state, form grey and/or black content actually, do not find as yet so far and can unify the whole zone of explanation, rational rationale.About this point, because the microtexture of the site set on each pixel of color printing image, promptly the site size that sets in H portion zone, zone line and the S portion zone is different with arrangement architecture, and to form difficulty be understanding easily so it is theoretical.But, should overcome this difficulty in order to improve printing technology.
As described below, the present invention is to be benchmark (being generally the C version) with color separation curve with version of all kinds (C, M, Y), seeks the reasonable establishing method of China ink version (B) with color separation curve.
The inventor has specialized in the color separation curve of how rationally setting as color separation operation core (gray shade scale transformation curve, tone reproduction curves).They have analyzed old way, promptly make various look versions in the past, when for example making the C version, by the R(redness of complementary colors relation) the concentration information value that optical filtering obtained and the relation of dot area % value be used to set C version color separation curve.Found new method promptly to utilize the photo concentration family curve of the color film photosensitive material of taking original image to become this concentration information value transform exposure value (because the present invention is included in it in this notion of light value simultaneously, so in the narration of back, adopt this term of light value), according to specific gray shade scale transform this light value is carried out the gray shade scale conversion, obtain dot area % value, promptly set out the color separation curve that concerns defined according to light value and dot area % value.In this case, no matter the original image quality is (for example under-exposed or excessive original copy, be difficult to original copy that duplicates with bright shelves or dark shelves and the original copy that shades of colour loss of gloss fault is arranged etc.) how, all can utilize this curve to obtain the good printed images of scale grade characteristic (special be willing to flat 1-135825 number, special hope flat 1-212118 number).
Moreover, according to the above-mentioned various look version color separation curves of stipulating by the relation of original concentration information value and dot area % value, owing in photographic film photosensitive material family curve, pay attention to the image information of concentration (Density) coordinate, thus below be referred to as D coordinate color separation curve.In contrast, as various look version color separation curves object of the present invention, that stipulate according to the relation of light value and dot area % value, because paying attention to horizontal ordinate (X coordinate) in this family curve is the image information of light quantity coordinate, so be called X coordinate color separation curve, a kind of curve before being different from clearly with this.
Because the concentration scale that can produce from H portion to S portion according to above-mentioned X coordinate color separation curve makes the people seem very natural (in other words concentration is linear) printed images, and can obtain also preferable image of tone, so the inventor has studied next step China ink version (B) and has listed the interior problem of setting technique that these look versions are used color separation curve in the setting technique of color separation curve.
Found that, pay attention to the setting technique of the version of all kinds (C, M, Y) of light value with X coordinate color separation curve, have now found that, in order to set China ink version (B), set earlier as the look version of benchmark X coordinate color separation curve, for example the C version is with X coordinate color separation curve, according to relation therewith, the B version of similarly setting out the attention light value can obtain the very gratifying printed images of picture quality with X coordinate color separation curve when carrying out polychrome plate-making like this.
The present invention as mentioned above, with in the past different fully, it takes much count of light value to the B version with the establishing method of color separation curve, and provides that a kind of (" skeleton " is black and all spendable novel B version color separation curve setting technique such as deceive entirely to any method for platemaking.
Briefly, the present invention relates to have the establishing method of the curve of grey-board used in multi-colour plate-making of following characteristics.In the method for setting curve of grey-board used in multi-colour plate-making,
(ⅰ) according to black print (B) in addition give the fixation version (color separation curve of any among C, M or the Y as benchmark, utilize the photo concentration family curve of the light reaching the film material of photochrome original copy, from original copy, obtain light value (X in the concentration information value (Dn) of pixel (n point) arbitrarily
n), obtain base light value (xn) again, by following " gray shade scale transform (1) " this base light value (xn) is transformed into dot area % value (a
Xn), set the color separation curve of representing by the relation of base light value and dot area % value as standard.
(ⅱ) to look version color separation curve, stipulate out the light value scope (X that the China ink version should be set as above-mentioned standard
BXH～X
BXS) and the dot area % value (a that should set
BH～a
BS).
(ⅲ) set required starting condition (ⅱ) and following " gray shade scale transform (1) is this light value scope (X according to above-mentioned China ink version
BXH～X
BXR) between the base light value (B of any pixel
Xn) be transformed into China ink version with dot area % value (a
BXn) set out China ink version curve.
" gray shade scale transform "
a
xn＝a
H+α（1-10
-K·xn）（a
s-a
H）/（α-β）……（1）
In the following formula:
Xn: with xn=(X
n-X
Hn) the base light value of expression, promptly utilize photo concentration family curve, from according to the reference color version with the pixel concentration value of information (D on the original image
n) the respective pixel light value (X that tries to achieve
n) in deduct concentration information value (D according to highlights (H) on the original image
Hn) light value (X of the corresponding highlights of trying to achieve
Hn) the base light value that obtains at last.
In the formula, the highlights (H portion) of China ink version also can be described as the position that begins to add China ink (black starting point portion).
a
Xn: with any dot area % value that sets of the pixel on the corresponding version of all kinds of pixel (C, M, Y) and the China ink edition (B) in the original copy.
a
H: predefined dot area % value in the black starting point portion of the highlights of version of all kinds or China ink version.
a
s: finish to add black position (black terminal point portion) in the darkest portion of version of all kinds or China ink version and go up predefined dot area % value.
α: for forming the surface reflectivity of the paper that printed images uses.
β: by β=10
-rThe numerical value that is determined.
K: by K=γ/(X
Sn-X
Hn) decision numerical value.
In the formula, X
SnExpression utilizes photo concentration family curve, according to the reference color version with the darkest portion (S) concentration information value (D on the original image
S) the darkest accordingly portion light value obtained.But the black terminal point of expression portion light value in the China ink version.
γ: represent any coefficient.
And for look version (C, M, Y) and China ink version (B), at xn, h, H
n, S
n, increase C, M, Y, B letter before H, the S, and then use " gray shade scale transform (1) ".
Fig. 1 represents the photo concentration family curve of color photographic light reaching the film material.
Fig. 2 represents standard colors version (C, M, Y) and various China ink versions (B) relation of X coordinate color separation curve.
Fig. 3 represents the look version (C, M, Y) that adopts in the embodiment and China ink version (B) relation with X coordinate color separation curve.
When Fig. 4 represents UCR each edition is with X coordinate color separation curve.
When Fig. 5 represents GCR each edition is with X coordinate color separation curve.
Technology formation of the present invention is described in detail as follows.
The 1.th use color separation curve in order to set China ink version (B) in the present invention, should obtain (X coordinate) color separation curve as of all kinds edition (C, M, Y) of benchmark with above-mentioned " tonal gradation transform (1) ". This be because, in the present invention, the position of taking is, According to the organic connections of its reference colours version color separation curve, namely utilize identical " tonal gradation transform (1) " to set China ink version (B) and use color separation curve. The China ink version (B) in past is used color separation curve with multi-color ink version (B). The China ink version (B) in the past establishing method of color separation curve, to set according to the relevant personnel's such as scan operation person experience as mentioned above, and, do not consider fully to stand on the such microcosmic position of each pixel of adding black scope and should add great site to each pixel, so the present invention and original technology have a great difference.
The following describes the method for setting its X coordinate color separation curve with the C version as the reference colours version. Certainly, also available its allochromatic colour version (M or Y) as the reference colours version.
As mentioned above, as the X coordinate color separation curve establishing method of the C version of benchmark, being not directly to by complementary colours R(redness among the present invention) the concentration information value that obtains from original photochrome original copy of optical filtering carries out the tonal gradation conversion.
Impact for the picture quality that is not subjected to the colored original (eurymeric, minus, light-transmission type, reflection-type, any all can) as the plate-making object, for example, for from over-exposed/normal/not enough original copy, the original copy of top grade/dark shelves, the original copy of various color spots is arranged or the original copy that fades is produced the good printed matter of picture quality, the present invention is not with the concentration information value but with the image information of light value as the tonal gradation conversion. This point and original technology differ widely.
In the present invention, utilize the characteristic curve of the color film photosensitive material (photosensitive emulsion) of taking original image, be so-called photo grey density characteristics curve (Photographic characteri-stic curve), be easy to obtain above-mentioned light value according to photo concentration (photographic density).
The following describes " the concentration information value " of not using original image to have when carrying out in the present invention tonal gradation conversion (the Continuous Gray Scale grade transformation becomes the site tonal gradation), and use the reason of " light value ". For to the different various original images of above-mentioned picture quality reasonably Carry out the tonal gradation conversion, if not use along with the color film photosensitive material separately intrinsic photo grey density characteristics curve change " concentration information value ", but use from shot object (therefore named think of justice, refer to the shooting basic object of original image, such as solid images, outdoor scene), be injected into the light value in this color film photosensitive material, so, because this is the image information that is not subjected to this photo grey density characteristics curvilinear motion, so no matter the original image quality how, all the tonal gradation conversion can be carried out uniformly reasonably, the basic thought of inventor's innovation that Here it is.
To the establishing method of C version with X coordinate color separation curve, existing on one side referring to chart, Yi Bian be elaborated.
(I) (1) at first should become function to the grey density characteristics curve of taking pictures of the color photographic light reaching the film material of taking original image in the present invention. Like this, just can be according to the concentration information value (D of any pixel in the original image (n point)n) obtain corresponding pixel light value (Xn). As long as each photo photosensitive material producer is become function as the photo grey density characteristics curvilinear transformation that technical data provides.
For example, Fig. 1 represents U.S. EK company Ai Keta counter-rotary-ing color processed film 64, i.e. the specialty photo grey density characteristics curve of film (daylight).
The following describes the formulation method of photo grey density characteristics curve shown in Figure 1.
When comparison film grey density characteristics curve carries out formulation, adopt proper method to carry out formulation and get final product, unrestricted.
For example, suppose ordinate=D=logIo/ I, abscissa=X(wherein will make the scale size of X coordinate consistent with the D coordinate), if a, b, c, d, f are constant, then carry out formulation with following each several part, get final product.
(1) the lower garden arc part (to the place of lower convexity, the zone that the D value is little) of photo grey density characteristics curve.
D＝a·b
c·（x+d）+e+f
(2) part of near linear (roughly be the place of straight line, the D value is the zone of median).
D=aX+b or
D＝a·X
2+b+c
(3) upper garden arc part (place that raises up, the zone that the D value is big).
D＝a·log｛b+（X+c）｝+d
Perhaps, characteristic curve is transformed into the halogen number, lower garden arc part～near linear part～upper garden arc partly is divided into many little line segments, makes each segment be similar to straight line. At this moment in order better to reproduce the tonal gradation of lower garden arc part and upper garden arc part, preferably this Region Segmentation is become as far as possible little line segment, make it be similar to straight line.
Moreover, as shown in Figure 1, because the photosensitive material of color photographic film has three kinds of emulsion characteristic curves of R/G/B, so, preferably version of all kinds is used respectively corresponding characteristic curve. In addition, also can use a kind of emulsion layer characteristic curve as easy method.
The results are shown in table 1. And in table 1, in order as far as possible correctly to represent photo grey density characteristics curve with numerical expression, the spy has been divided into many formulation sections.
In the present invention, when photo grey density characteristics curvilinear transformation shown in Figure 1 is become function, the X coordinate scale of the D coordinate scale that will represent earlier photochrome original copy concentration value and expression light value (this value is that the logE of solid images represents by the made thing body) is decided to be identical size, and then the function of definite D and X.
Scale about D coordinate and X coordinate determines that according to following viewpoint the inventor thinks that this is fully reasonably.
Be the logarithm value E(logE=logI that in the photo concentration family curve X coordinate is decided to be exposure * t), this is determined by people's the vision logarithm distinctive feature to light and shade.In addition, the logarithm physical quantity shown in the D coordinate representation literal, this also is the vision according to the people, presses logarithm and determines.So, when asking the mutual relationship of D value and X value, though under identical scale condition also without any un-reasonable phenomenon.
Moreover in the present invention, the determining of above-mentioned scale is a kind of easy method, and be self-evident, is not limited in this method.For example, also can be write as function by the numerical relation of D coordinate shown in Figure 1 and X coordinate.In its relative meaning, the present invention uses the physical quantity of " light value " this term as the X coordinate, as the notion that comprises exposure value.
(I) (2) the present invention is not with photochrome original concentration of information value (D as mentioned above
nValue) be the basis, but with subject (solid images, the outdoor scene) image information value that given, promptly by the represented light value (X of X coordinate
nValue) is the basis.
As mentioned above, photo concentration family curve is as shown in table 1, D
nValue and X
nValue is passed through X=f(D) functional expression represent mutual relation, so be easy to from D
nObtain X in the value
nValue.
(I) (3) can obtain the light value (X that subject (solid images) gives as stated above
n).Then, as long as utilize the reasonable like this X that obtains
nValue and above-mentioned " gray shade scale transform (1) " are obtained the X coordinate color separation curve (this curve can replace the D coordinate color separation curve of the sort of attention concentration information in the past) of paying attention to light value and are got final product.That is to say, according to the concentration value (D of any pixel (n point) of given photo concentration family curve from the photochrome original copy
n) obtain the pixel light value (X on the corresponding subject (entity portrait)
n).With this X
nValue substitution above-mentioned " gray shade scale transform (1) " can calculate the dot area % value as the gray shade scale intensity level, sets out X coordinate color separation curve.Moreover, when using " gray shade scale transform (1) ", light value (X as mentioned above
n) should be transformed into base light value (xn), this is for the predefined dot area % of H portion and S portion value (a
H, a
S) the necessary preliminary work of substitution.In addition, in order to make the C version, as long as manage to make the halftone generator of colour scanner to move with X coordinate color separation curve according to this C version.
The derivation of following brief description above-mentioned " gray shade scale transform (1) " of the present invention.
The dot area % value (a that each pixel set during employing " gray shade scale transform (1) " was calculated original image when utilizing the site gray shade scale to make printed images
Xn), this transform (1) is with the concentration formula that It is generally accepted (photo concentration, optical concentration), promptly with
D＝logI
o/I＝log1/T
I in the formula
o=incident light quantity
I=reflection light quantity or transmission light quantity
T=I/I
o=reflectivity or transmissivity
For benchmark derives out.
The general formula of relevant this concentration D then becomes following form if be used for plate-making, printing.
Concentration (D ')=logI when plate-making, printing
oThe reflectivity of/I=log(unit area X paper)/{ surface reflectivity of the reflectivity+dot area of (unit area-dot area) * paper * printing ink }=log α A/ (α { A-(d
1+ d
2+ ... d
n)+β (d
1+ d
2+ ... d
n))
In the formula:
A: unit area
d
n: the area of each site in the unit area
α: the reflectivity of printing
β: the surface reflectivity of printing paint
The present invention is derive so above-mentioned " gray shade scale transform (1) ", promptly based on this concentration formula (D ') of making a plate, printing, image information does not adopt concentration value and adopts light quantity, the dot area % value (a of the specimens point on the base light value (xn) of the specimens point (pixel) (n point) on the original image of while Continuous Gray Scale grade and the site gray shade scale printed images corresponding with it
Xn) relation, its theoretical value will reach consistent with measured value.
When utilizing above-mentioned " gray shade scale transform (1) " of the present invention, a
H, a
SParameter generally adopts constant, for example, and the dot area % value of C version, a
CH Adopt 5%a
Cs Adopt 95%, a of M and Y version
MH=a
YHAdopt 3%, a
MS=a
YS Adopt 90%.Moreover, utilizing above-mentioned " gray shade scale transform (1) ", utilize X
nValue (X
nValue is basis and D
nThe relation of value is obtained, and D
nValue is that densimeter records), if a
HAnd a
sAdopt percent numerical value, then a
XnValue is also pressed the percent numerical evaluation.
When utilizing " gray shade scale transform (1) " of the present invention, other important parameters γ value owing to following reason, generally can be thought constant when setting C version color separation curve.Promptly when setting the C version, can adopt fixed value, i.e. γ value=0.45 with X coordinate color separation curve.This experience when to be the inventor in the process of exploitation " gray shade scale transform (1) " of the present invention according to the past exploitation adopt concentration value as the gray shade scale transform of image information value derives out.The basic structure of this gray shade scale transform and the present invention do not have too big difference, but γ value has at that time adopted the β concentration value of γ value=0.9～1.0 this Yellow ink.Adopting the reason of Yellow ink β concentration value is that Yellow ink is compared with other printing ink in printing-ink, concerning people's vision, and the former values maximum.Can set out the D coordinate color separation curve that is fit to very much actual color separation operation whereby.Become the present invention of light value for image information value from the concentration information value transform, the γ value approximately can reduce half, i.e. γ=0.45.This point by many experimental examples in confirm.When the concentration information Change of Class was light value, the γ value should change to γ=0.45 in the gray shade scale conversion, and its principle can be illustrated according to the characteristic shape of photo concentration.Can change over the size that meets purpose to the γ value like this, the understanding this point is very important for purposes of the invention.Moreover γ is as described below for this parameter, can change the shape of color separation curve, makes it meet purpose.In other words, control the γ value, can produce printed matter with required scale grade characteristic according to purpose.Therefore, the γ value is an important parameter.So the γ value is not fixing as above-mentioned value.
The setting of the parameter value of " gray shade scale transform (1) " of the present invention is looked following two kinds of different requirements and different, a kind of be the tone true reappearance of given subject (photo in kind) on printed images; Another kind is to produce the printed images of revising or changing tone consciously.The latter can be modified to required shape to the shape of X coordinate color separation curve, so can be made into the printed images of various tones by changing the γ value consciously.For example, (in the time of will emphasizing the tone of H portion～intermediate luminance) was decided to be the γ value greater than 0 when the alteration of form of X coordinate color separation curve was become to raise up, and adjust to when almost being straight line, and the γ value is decided to be near 0; On the contrary, adjust to when recessed (in the time of will emphasizing the tone of intermediate luminance～shadow part) is decided to be negative value with the γ value and gets final product.
When utilizing above-mentioned " gray shade scale transform (1) " of the present invention, certainly it is changed over following form, also can process arbitrarily it, re-use after distortion and the derivation.
a
xn＝a
H+E（1-10
-k·xn）·（a
S-a
H）
……（2）
In the formula, E=1/(1-β)=1/(1-10
-γ)
Suppose α=1 in the above-mentioned formula modified example.
This is that the surface reflectivity that shows the printing paper (base material) that printed images adopted is decided to be 100%.The α value can be got arbitrary value, still, is to carry out zero point according to the whiteness of paper to adjust in real work, is no problem so the α value is decided to be 1.0.
Moreover, according to above-mentioned formula modified example (α=1.0), can be with predetermined a
HValue is set on the highlights H of printed images, with predetermined a
SValue is set on the darkest S of portion.This is maximum characteristics of the present invention.This point can obviously be found out from following situation: on the highlights H of printed images, and according to definition, xn=0, xn=X on the darkest S of portion
Sn-X
Hn, promptly
-K·xn＝-γ·（X
Sn-X
Hn）/（X
Sn-X
Hn）＝-γ。
Like this, can be when " gray shade scale transformation curve (1) " (modified example of α=1) of the present invention when utilizing with predetermined a
HAnd a
SValue is set on the printed images.This is very important for the user of service checks the operation result.For example, with a of printed images
HAnd a
SBe set at required numerical value, change γ value (wherein α=1.0), can obtain various X coordinate color separation curves.And and, according to the printed images that these X coordinate color separation curves are made, be easy to identify according to the relation of itself and γ value.
Particularly in the real work of plate-making, very the more important is, the X coordinate color separation curve of trying to achieve according to the present invention is different from D coordinate color separation curve in the past, and the former can be expressed as scale grade characteristic and the tone of H～S on the printed images of final products.That is to say that the plate-making operator can be according to given a
H, a
SWith the X coordinate color separation curve that the γ value is tried to achieve, can dope the processing effect (tone) of final printed images accurately by observation to its shape.This is that promptly for several original images of picture quality difference (for example conditions of exposure difference), the X coordinate color separation curve of She Dinging all is summarised on the same curve respectively because gray shade scale transform method of the present invention has so very big characteristics.In contrast, the D coordinate color separation curve in past (adopts identical a
H, a
SWith the γ value), different according to picture quality, make and the corresponding curve of original image respectively, curve shape is very complicated.So, in the plate-making operation, only depend on and observe its curve, can not accurately predict the quality of final printed images.Above-mentioned situation has very important significance, the plate-making operating personnel show the X coordinate color separation curve of version of all kinds (C, M, Y) and China ink version (B) by monitor, can predict the crudy of final printed images exactly, so do not need to carry out various correction operations.That is to say, utilize the present invention's can directly make a plate (direct-to-plate).
In addition, when utilizing above-mentioned " gray shade scale transform (1) " of the present invention, also can adopt regular standing procedure, i.e. K=γ, just (XS
n-X
Hn) value equals 1.0.Like this, X
Hn～X
SnThe dynamic range of value is if unified (standardization) is 0～1=1.0, and then the calculating of " gray shade scale transform (1) " is easily.Certainly, the light value (xn) of each pixel in the dynamic range also will be unified scope by this and change.But owing to be relative variation, thus to the setting of color separation curve without any influence.Moreover, below will utilize above-mentioned numerical value after reunification to describe.
The gradation of image grade transformation method that the present invention utilizes above-mentioned " gray shade scale transform (1) ", for the gray scale and the tone that reproduce subject (solid images), promptly the tone of subject is very effective according to 1: 1 and quality repeatability are reproduced on the printed images well.But its validity is not limited only to this.Above-mentioned " gray shade scale transform (1) " of the present invention, it has commentaries on classics, except reproducing truly the characteristic of subject, can also be by suitably selecting α, γ value and a
H, a
SValue reasonably changes or revises the picture characteristics of subject.
Secondly,, adopt " gray shade scale transform (1) " of the present invention when setting X coordinate color separation curve respectively, can carry out by the following method polychrome plate-making (generally these four kinds of versions of C version, M version, Y version and B version being called one group).Because most important version is the C version in the polychrome plate-making, above-mentioned " gray shade scale transform (1) " derives out from reasonably determining this viewpoint of C version.So, utilize above-mentioned " gray shade scale transform (1) " at first to set the X coordinate color separation curve of C version usefulness, the X coordinate color separation curve of other M version, Y version usefulness is then by being multiplied by well-known suitable adjusted value in the industry, to keep gray balance and colour balance, can determine other curves like this.
In addition, the establishing method of the X coordinate color separation curve of China ink version (B) usefulness is as follows.
(ⅱ) as the C version color separation curve of benchmark in case after setting as stated above, will determine China ink version (B) to set required condition with that with color separation curve.
This is the preliminary condition enactment of China ink version, and promptly with respect to the C version color separation curve as benchmark, what scope is China ink version (B) be set in, and adds the China ink of much amounts.
That is to say to determine what light value scope (X is China ink version (B) be set to
BxH～X
BxS) (XH represents the pixel of black starting point portion; XS represents the pixel of black terminal point portion), and respectively how big China ink terminal point portion of black starting point portion set dot area % value (a
BH～a
BS).If so black version (B) is set with the decision in a single day of preliminary condition, just can utilize above-mentioned " gray shade scale transform (1) ", the same B version X coordinate color separation curve of setting out with the C version.Each pixel is set out best dot area % value.
With respect to C version X coordinate color separation curve, as dot area % value, if at 50%(a
Cxn=50) add China ink in the above zone, so, the base light value (B of black starting point portion
Xn) can obtain by following formula.
B
xn＝-1/γ·log｛1-（a
cxn-a
H）（1-10
-γ）/（a
s-a
H）｝……（3）
In the formula, a
Cxn=50, or 50 above any number.Other parameters, γ=0.45 for example, a
S=95, a
H=5.
Moreover, according to (3) formula as can be known, as the black terminal point a of portion
Cxn=a
SThe time, B
Xn=be 1.0.So, the light value scope (X of terminal point portion of black starting point portion～black
BxH～X
Bxn) can according to the C version with the relation of color separation curve, be set at (B
Xn～1.0).
Above-mentioned black starting point portion and black terminal point portion are set out the dot area % value a of China ink version (B) usefulness
BH, a
BS(for example 5%, 65%), and under the condition of given γ value, utilize " gray shade scale transform (1) " can obtain China ink version (B) and use color separation curve.In addition, when utilizing " gray shade scale transform (1) ", adopt and ask C version color separation curve time institute accepted standard computation process (method).Promptly the dynamic range (X of terminal point portion of black starting point portion～black
BXH～X
BXS)=(B
Xn～1.0) unify (standardization) when being (0～1.0), the calculating of " gray shade scale transform (1) " is very easy.Even carry out such standardization, can not produce any influence with color separation curve to resulting B version yet.This point is illustrated in the establishing method of C version with color separation curve.
Now utilize numerical value more specifically etc. that the establishing method of above-mentioned China ink version (B) with color separation curve is illustrated.
(I) China ink version design data (data)
1. as C version the imposing a condition of benchmark with color separation curve
1. color photographic film: the EK corporate system Ai Keta of Kodak reversal colour film 64(is referring to Fig. 1)
2. the characteristic relational expression of (sheet) concentration of taking pictures of color photographic light reaching the film material: referring to table 1
3.＜gray shade scale transform (1) the utilization condition:
a
CH=5%, a
CS=95%, r
CValue=0.45
2. black version (B) imposing a condition with color separation curve
1. the scope that adds the China ink version: the C version with color separation curve in dot area % value be in 50%～95% the scope.
2. the dot area % value of China ink version: (black starting point portion) 5%～(black terminal point portion) 65%
3. China ink version is set usefulness＜gray shade scale transform (1)〉the utilization condition:
a
BH=5%, a
BS=65%, r
BValue (referring to table 2)
(II) China ink version (B) is used color separation curve
1. black edition (B) uses the set data (calculated value) of color separation curve: referring to table 2
2. China ink version (B) is used color separation curve: in Fig. 2 (representing table 2) table 2 with figure, and a
CxnBe the dot area % value of the given pixel (xn) of C version, C
XnBe the base light value of the given pixel (xn) of C version, Bxn represents above-mentioned Cxn is standardized as 1.0 and the base light value of the given pixel of B version (xn) of trying to achieve.
Moreover Fig. 2 represents C version color separation curve, and its data are shown in table 3.
And Fig. 2 also represents M version, Y version color separation curve.M version, imposing a condition of Y version are: concerning the C version, locate to keep the poor of 10% dot area % value in medium tone (being the position of 50% site on the C version); H portion keep 2% poor; S portion keep 5% poor, and keep the euchroic balance.
The table 3 C version setting data complete list of color separation curve
| The step number | Original copy concentration value (Dn) | Light value (Xn) | Base light value (Xn-X Hn) | Standardization light value (xn) | Dot area % value (acxn) |
| 1 2 3 4 5 6 7 8 9 10 11 12 | 0.2900 0.4190 0.5480 0.8060 1.0640 1.3220 1.5800 1.8380 2.0960 2.3540 2.6120 2.8700 | 0.6187 0.8233 0.9618 1.1517 1.3259 1.4716 1.6025 1.7315 1.8605 1.9914 2.1261 2.2967 | 0.0000 0.2046 0.3431 0.5330 0.7072 0.8529 0.9838 1.1128 1.2418 1.3727 1.5074 1.6780 | 0.0000 0.1219 0.2045 0.3176 0.4215 0.5083 0.5863 0.6632 0.7400 0.8181 0.8983 1.0000 | 5.0000 21.5516 31.6360 44.1160 54.3608 62.1133 68.5096 74.3286 79.6956 84.7327 89.4979 95.0000 |
Utilize the above method can be according to reasonably setting B version color separation curve with the relation of color separation curve with benchmark C version.Moreover, according to the above description, in the whole zone of terminal point portion of black starting point portion～black, all utilize＜really spend grade transformation formula (1)〉set B version color separation curve.But also use＜gray shade scale transform (1) in this regional part only〉set B version color separation curve, other equations of use (straight line, quafric curve etc.) are set B version color separation curve in other zones simultaneously.
In long-term take pictures plate-making and color separation technology performance history, people generally believe " the China ink version is that colored printing ganmma controller grade and tone finally reach perfect important version ".And accumulated many experiences in use all the year round, for example, the China ink version is applicable to the visual light of version of all kinds (C, M, Y), and (brightness) then reduces gray shade scale curve gradient to medium tone; Shade is then increased gray shade scale curve gradient.
Yet, as previously mentioned, utilize original technology, because the image quality of photochrome original copy is ever-changing, the version of all kinds (C, M, Y) of making in addition by the color separation operation, the gray shade scale instability of its site gray shade scale image, reason such as can not meet the demands, the advantage of China ink version can not be given full play to.And utilize the present invention, and then can reasonably set the China ink version by said method, produce the very excellent printed matter of true degree grade by polychrome.
(embodiment 1)
Below further describe China ink version of the present invention (B) establishing method by embodiment with color separation curve.
(1) photochrome original copy
The photochrome original copy has been selected the reference image quality photo of having taken the women with EK corporate system 4 " * 5 " positivity color film (Ai Keta reversal colour film 64) for use.
Moreover, red by R(), G(is green), the B(orchid) the H portion of the photochrome original copy that records of optical filtering of all kinds and the dense density value of S portion be as shown in table 4.
The H portion of table 4 photochrome original copy and the concentration value of S portion.
| Densimeter optical filtering color | H portion | S portion |
| R (redness) G (green) B (blue look) | 0.29 0.28 0.28 | 2.87 2.97 2.96 |
(2) color separation operating condition (version of all kinds)
Common way is according to keeping the condition of gray balance to carry out between version of all kinds in the color separation of version of all kinds (C, M, Y), the industry.More particularly, the H portion of C version is set at 5% dot area % value, (brightness) is set at 50% to medium tone, and S portion is set at 95%; H portion to M version and Y version is set at 3% dot area % value, and medium tone is set at 40%, and S portion is set at 90%.And, when setting the C version and use color separation curve,＜gray shade scale transform (1)〉r
CValue adopts r
C=0.45.The r value of M version, Y version then adopts r
M=r
Y=0.1850, its purpose is to satisfy above-mentioned gray balance condition.
The C version is shown in table 3 with imposing a condition of color separation curve.These impose a condition the Ai Keta of Kodak reversal colour film 64(specialty usefulness shown in Figure 1, daylight), by becoming function shown in the table 1, obtain D with this
nValue → light value (X
n) → base light value (X
n-X
Hn) → standardization light value (X
n), utilization＜gray shade scale transform (1)〉obtain the C version with dot area % value (a
Cxn).
(3) the plate-making design of China ink version
According to above try to achieve determine the usable range of China ink version as the dot area % value of the C version of benchmark, set the dot area % value of black starting point portion and black terminal point portion simultaneously and ask the China ink version use color separation curve required＜gray shade scale transform (1) r
BValue.The present embodiment being pressed and setting these conditions shown in the tabulation 5, and the B version of obtaining according to these conditions is shown in table 6 with the set data (data) of X coordinate color separation curve.And,, B version and version of all kinds (C, M, Y) are shown in Fig. 3 in the lump with X coordinate color separation curve according to the data of table 6.
(table 5) China ink version design data
| The B version usable range of determining according to C version dot area % value | The China ink version | |
| The dot area % value of terminal point portion of China ink starting point portion/black | |
|
| 20% | 3.0000 | -1.0000 |
| 95% | 60.0000 | ～-1.5000 |
The table 6. China ink version set data (data) of color separation curve
(B version dot area % value)
(4) plate-making
The magnetic scanner 646 that scanner adopts Crouse Fei De company to produce, look is proofreaied and correct Ku Luomalin (Chromarine) correction method of adopting E.I.Du Pont Company.
Making a plate the design phase by the colored printing image that above method is made, the black starting point portion of China ink version (B) is set at bright portion (20% site of C version) by predetermined scheme, so the meticulous tone of bright portion can reproduce out well, although medium tone also adds China ink, but still can keep the gray shade scale of the lucid and lively exquisiteness of tone, and the compacting of the tone of shadow part (closely knit) degree is good, and quality can fully meet the demands.
(embodiment 2)
China ink version (B) and of all kinds edition (C, M, Y) that the present embodiment attempts to make such purposes promptly utilize the sheet-fed four-color press by the wet printing method and at the UCR(undercolour removal) when carrying out colored printing under the condition.
(1) photochrome original copy
The photochrome original copy adopts the photo of the reference image quality taken water mill room, rural area, and used film is identical with above-mentioned embodiment 1 during shooting, i.e. 4 " * 5 " Ai Kuta reversal colour film 64 of EK company production.This photochromatic original image, because the relation of photography time and photography direction, picture dash area on the whole is more.
In addition, the H portion of the color photographic original copy of measuring by R, G, B optical filtering of all kinds and the concentration value of S portion are shown in table 7.
The H portion of table 7, color photographic original copy/S portion concentration value
| Densimeter optical filtering color | H portion | S portion |
| R (redness) G (green) B (blue look) | 0.36 0.39 0.38 | 2.83 2.84 2.84 |
(2) plate-making of the version of all kinds (C, M, Y) behind China ink version (B) and the undercolour removal is established
The operation process of the plate-making design of China ink version (B) is identical with embodiment 1 basically.But consider the design of making a plate of following plate-making condition.
Because the whole picture top shadow of color photographic original copy is more, so the amount that adds China ink version (B) is less than the common employing amount of the industry slightly.
In addition, owing to adopt the wet printing method to carry out colored printing, so the dot area % value total amount of these 4 versions of the C of S portion, M, Y and B roughly is decided to be 270% according to the method in past, approximately is decided to be 280% according to the present embodiment.Specifically, the S portion of C version adds 70% site, and the S portion of M version and Y version adds 60%, and the S portion of B version adds 90%, adds up to 280%.
Moreover, the scope of adding China ink version (B), Jimo starting point portion (STP) and black terminal point portion (EDP) according to the standardization light value, are decided to be 0.25～1.00.So the X coordinate color separation curve during version of all kinds (C, M, Y) undercolour removal should suitably make alterations according to the dot area % value of the adding of China ink version (B) and above-mentioned S portion as shown in Figure 4.The shape of X coordinate color separation curve can be according to＜gray shade scale transform (1) in the present invention〉the r value carry out suitable change.
Above-mentioned plate-making design conditions is summarized in the table 8.The set data (data) of the X coordinate color separation curve of China ink version (B) that try to achieve according to these conditions, when background color is eliminated (UCR) and version of all kinds (C ', M ', Y ') is shown in table 9, and the X coordinate color separation curve of try to achieve according to the data of table 9 again of all kinds edition (C ', M ', Y ' and B) is shown in Fig. 4.In addition, identical with Fig. 3, the X coordinate color separation curve of the version of all kinds (C, M, Y) when not carrying out undercolour removal (UCR) also is shown in Fig. 4 together.
The plate-making design data of the various version usefulness during table 8. undercolour removal
| Look version before the UCR | Look version behind the UCR and China ink version | ||||||
| C | M.Y | C ′ | M ′ ′Y ′ | B(1) | B(2) | ||
| Standardization light value district | STP(?XHn) EDP(XSn) | 0.000 1.000 | 0.000 1.000 | 0.000 1.000 | 0.000 1.000 | 0.250 1.000 | 0.250 1.000 |
| Dot area % value usable range | STP(a H) EDP(a S) | 5.000 95.00 | 3.000 90.00 | 5.000 70.00 | 3.000 ※ 59.90 | 0.000 90.00 | 0.000 90.00 |
| The γ value | 0.450 | 0.185 | 1.000 | 0.900 | -1.00 | -1.50 | |
This numerical value of ※ is meant to satisfying when the C version set 70% dot area % value and should reaching gray balance when M version, the overlapping printing of Y version this requires the dot area % value of necessary M version and Y version.In addition, this numerical value is to obtain according to the dot area % value correlation table (this table relates to the C version and M, Y version keep gray balance) that the inventor works out.
(3) plate-making
Used scanner and look correction method and embodiment 1 are identical.
The colored printing image of making according to above plate-making method for designing, its processing tone can reach predetermined state of plate-making design phase fully, can fully satisfy the demand as the plate-making technology that the wet printing method is used.Appear on the whole colored original, particularly the shade of (brightness) can attenuate from the light to medium tone, makes tone give people one good printing, can reach the brightness of expection concerning people's vision.
(embodiment 3)
GCR(is long apart from undercolour removal, complete black) though deliver in the document of relevant printing in the past, in fact do very difficulty.The establishing method of the China ink version (B) when the present embodiment is carried out GCR with explanation stresses wherein how the China ink version (B) as main version is rationally set according to the present invention under the GCR condition.
(ⅰ) plate-making of China ink version (B) design
In the dot area % value of the China ink version of setting under the GCR condition (B) with carrying out the total of the dot area % value that sets on of all kinds edition of undercolour removal (UCR) (C ', M ', Y ') under this China ink version (B) condition, the total of the dot area % value of the version of all kinds (C, M, Y) of the standard of (hereinafter referred to as " before the GCR ") when not carrying out undercolour removal (UCR) is set the China ink version (B) under the GCR condition under the such two kinds conditions that add up to dot area % value to equate.
The color separation curve of the version of all kinds (C, M, Y) of the standard before the above-mentioned GCR, it imposes a condition and is shown in table 10.Utilize the present invention, utilization＜gray shade scale transform (1) under these setting data conditions〉when setting color separation curve, the tone (gray shade scale) that can produce H portion～S portion under this color separation curve condition seems very natural colored printing image.No matter be the setting of each color separation curve under the UCR condition of above-mentioned embodiment 2, or the setting of the color separation curve under the GCR condition of the present embodiment, in utilization＜gray shade scale transform (1)〉condition under all can obtain above-mentioned good result.
(table 10)
Version of all kinds before table 10 GCR setting data of color separation curve
| H portion site | The medium tone site | S portion site | r | |
| C | 5.00 | 50.00 | 95.00 | 0.450 |
| M.Y | 3.00 | 40.00 | 90.00 | 0.185 |
Secondly, the standardization light value scope that under the GCR condition, adds China ink version (B), UCR(scope 0.250～1.000 than embodiment 2) wide, be decided to be 0.050～1.000, dot area % value to black starting point portion (STP) and black terminal point portion (EDP) should set is decided to be 0.00% and 100.00% respectively.
Moreover the version of all kinds under the GCR condition (C ', M ', Y ') is definite by the following method with imposing a condition of color separation curve.
That is to say, when determining the data of table 11, with reference to following numerical value: 4 look dot area % values of S portion are about the setting value of this industry of 270% (this are according to factor such as the printing ink transfer printing is bad when utilizing the wet printing method to carry out colored printing, the definite rational value in conjunction with practical experience) and consider gray balance, version of all kinds and under the UCR condition shown in the embodiment 2 (C ', M ', Y ') employed r value when setting with color separation curve.Moreover according to the data of table 11, above-mentioned each edition of the total dot area %C '+M '+Y '+B(of S portion adds up to)=275, be consistent with aggregate value C+M+Y=275 before the GCR of table 9.
(table 11)
The version of all kinds setting data of color separation curve during table 11 GCR
| H portion site | The medium tone site | S portion site | The r value | |
| C | 5.00 | 50.00 | 65.00 | 1.000 |
| M.Y | 3.00 | 40.00 | 55.00 | 0.832 |
Three kinds of look versions dot area % value separately adds up to after obtaining C, M before the GCR of each standardization light value, three kinds of look versions of Y and GCR below, according to both poor (hereinafter referred to as △ DOT), and the set data (data) of B version usefulness color separation curve when having formulated GCR.
At this moment,, the light value scope is divided into 0.05～0.35,0.35～0.65,0.65～1.00 three section for the ease of setting B version color separation curve, suitably selection be adapted to each section＜gray shade scale transform (1) the r value.Obtain the B version color separation curve of each section.At this moment a that sets of highlights in each zone and the darkest portion
BH, a
BSThe r value that value (this value is by △ DOT decision) and each section use is shown in table 12
(table 12)
The B version during table 12 GCR setting data of color separation curve
| The standardization light value scope of colored original | a BH | a BS | The r value |
| 0.05～0.35 0.35～0.65 0.65～1.00 | 0.00 15.44 51.09 | 15.44 51.05 100.00 | -0.825 -0.135 0.0001 |
Each edition is summarized in the table 13 with the setting data of color separation curve during above GCR.And the setting data of the X coordinate color separation curve of China ink version (B) the during GCR that tries to achieve according to these conditions and version of all kinds (C ', M ', Y) is shown in table 14, and the X coordinate color separation curve of further obtain according to the data of table 14 of all kinds edition (C ', M ', Y ' and B) is shown in Fig. 5.In addition, when asking the X coordinate color separation curve data of China ink version (B) (1), (2), (3) according to the data of table 13, if three light value sections (0.05～0.35,0.35～0.65,0.65～1.00) are standardized as 1.0 respectively, utilization＜gray shade scale transform (1) 〉, then can improve counting yield.And do not express B(1 among Fig. 5), B(2), B(3) tune.And in Fig. 5, the same with Fig. 3, Fig. 4, also expressed the X coordinate color separation curve of the version of all kinds (C, M, Y) before the GCR simultaneously.
Shown in above-mentioned table 14, (black edition (B) of the △ DOT value of STP～EDP) during with GCR as if being compared, can find out then that its consistance is very good with the setting data of color separation curve in the whole zone that adds China ink (B).It is professional, no problem that the China ink version of setting like this (B) goes for actual plate-making.That is to say that the version color separation curve of all kinds when utilizing the present invention reasonably to set GCR especially lack and set theory and methodology, and the China ink version (B) that is difficult in the past set is used color separation curve.
The present invention can provide the reasonable method that China ink version (B) is used color separation curve of setting, and it has following good result.
(I) can say so, and utilizes technology in the past, and version of all kinds (C, M, Y) will rely on scanner producer or operation of scanner personnel's experience and cognition to make with color separation curve (China ink version (B) also is like this with color separation curve). That is to say, seem very natural printed image in order in the gamut of the H of original image section～S section, one by one small pixel to be become tone, it is all unresolved how to set suitable this theoretical issues of dot area % value, so these color separation curves can be described as the dependence experience and know from experience and work out. Compare with the above-mentioned technology in past, the present invention is a kind of very reasonably method, for shining, the unified colour of processing various image qualities resembles original copy, adopt " light value " as the pictorial information value of original copy, simultaneously, utilize specific " tonal gradation transform " to set the color separation curve of version of all kinds (C, M, Y), set China ink version (B) according to its correlation and use color separation curve.
(II) expression " light value " (particularly light value after the standardization) and utilize dot area % value that " tonal gradation transform " of the present invention try to achieve the two correlation, X coordinate color separation curve, can demonstrate the version of all kinds of H section as the colored printing image of product～S section and the tonal gradation of China ink version (C, M, Y and B), so, shape by this curve of observation analysis, can judge in advance the quality as the colored printing image of final products, therefore, can directly produce galley according to resembling original copy according to colour, for polychrome plate-making (comprises China ink Version) direct plate graphic arts process has been opened up road.
(III) is owing to can reasonably having made any China ink version, so the characteristics that can take full advantage of the China ink version are produced the high-quality color printed image that meets customer requirements.
(IV) can take full advantage of the advantage of China ink version in addition, saves the energy etc. such as adjustment, the maintenance of gray balance, the minimizing of printing ink use amount, the raising of print speed printing speed, the rear ink oven dry of printing of shadow part.
(V) color separation operation key problem tonal gradation conversion relevant with above-mentioned (I) bar, that comprise China ink version (B) establishing method (certainly, comprising the color separation curve setting technique), found rational rationale, so the past always thinks that the color separation technology that is difficult to explain can reasonably be illustrated now.
Claims (5)
1, polychrome making sheet China ink version curve setting method is characterized in that:
(i) according to China ink version (B) color separation curve in addition to fixation system (any one among C, M or the Y) as benchmark, utilize the photo concentration family curve of the light reaching the film material of photochrome original copy, from original copy, obtain light value (Xn) in the concentration information value (Dn) of pixel arbitrarily, obtain base light value (xn) again, this base light value (xn) is transformed into dot area % value (a by following " gray shade scale transform (1) "
Xn), set out by usually representing the pass of base light value and dot area % value, as the look version color separation curve of standard,
(ii), stipulate out the light value scope (X that the China ink version should be set to look version color separation curve as above-mentioned standard
BXH～X
BXS) and the dot area % value (a that should set
BH～a
BS),
(iii) set required starting condition (ii) with following " gray shade scale transform (1) is this light value scope (X according to above-mentioned China ink version
BXH～X
BXS) between the basic light value (B of any pixel
Xn) be transformed into China ink version with dot area % value (a
BXn), set out China ink version curve;
" gray shade scale transform (1) "
a
xn=a
H+d(1-10
-K·xn)(a
S-a
H)/(α-β)……(1)
In the following formula:
Xn: use xn=[X
n-X
Hn] the base light value of expression, promptly utilize photo concentration family curve, from according to the reference color version with the pixel concentration value of information on the original image
(D
n) the corresponding pixel light value (X that tries to achieve
n) in, deduct concentration information value (D according to highlights (H portion) on the original image
Hn) light value (X of the corresponding highlights of trying to achieve
Hn), last resulting basic light value,
Wherein, the highlights (H portion) of China ink version also can be described as the position that begins to add China ink (black starting point portion),
a
Xn: for original copy in any dot area % value that sets of the pixel on the corresponding various look versions of pixel (C, M, Y) and the China ink edition (B),
a
H: predefined dot area % value in the black starting point portion of the highlights of version of all kinds or China ink version,
a
S: finish to add black position (black terminal point portion) in the darkest portion of version of all kinds or China ink version and go up predefined dot area % value,
α: for forming the surface reflectivity of the paper that printed images uses,
β: by β=10
-rThe numerical value that is determined,
K: by K=γ/(X
Sn-X
Hn) numerical value that determined,
In the formula, Xsn represents to utilize photo concentration family curve, according to the reference color version with the concentration information value (D of the darkest portion on the original image (S portion)
S) obtain the light value of dark portion accordingly.But the black terminal point of expression portion light value in the China ink version,
γ: expression is counted arbitrarily,
And, before xn, n, Hn, Sn, H, S, increase C, M, Y, B letter for look version (C, M, Y) and China ink version (B), use then " gray shade scale transform (1) ".
2, as the establishing method of the curve of grey-board used in multi-colour plate-making put down in writing in the claim 1, wherein the photo concentration family curve of photochrome original copy photographic film photosensitive material is to utilize with the ordinate concentration value, is that the expose to the sun orthogonal coordinate system of light value is represented with horizontal ordinate.
3, as the polychrome system of being put down in writing in the claim 2 China ink version curve setting method, wherein make the horizontal ordinate scale be fit to ordinate concentration value scale.
4, the curve of grey-board used in multi-colour plate-making establishing method as being put down in writing in the claim 1, wherein as the color separation curve root C version of other editions of benchmark with color separation curve.
5, the curve of grey-board used in multi-colour plate-making establishing method as being put down in writing in the claim 1, wherein the light value scope (X that obtains according to the concentration information value of other editions
Hn～X
Sn) formally be decided to be 1.0(0～1.0).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91102282 CN1065738A (en) | 1991-04-10 | 1991-04-10 | The establishing method of curve of grey-board used in multi-colour plate-making |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91102282 CN1065738A (en) | 1991-04-10 | 1991-04-10 | The establishing method of curve of grey-board used in multi-colour plate-making |
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| Publication Number | Publication Date |
|---|---|
| CN1065738A true CN1065738A (en) | 1992-10-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91102282 Pending CN1065738A (en) | 1991-04-10 | 1991-04-10 | The establishing method of curve of grey-board used in multi-colour plate-making |
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| CN (1) | CN1065738A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102183224A (en) * | 2011-03-15 | 2011-09-14 | 西安理工大学 | Method for detecting screen dot of measurement and control strip based on machine vision |
| CN104943358A (en) * | 2014-03-27 | 2015-09-30 | 北大方正集团有限公司 | Generation method and device for printing machine characteristic curve |
-
1991
- 1991-04-10 CN CN 91102282 patent/CN1065738A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102183224A (en) * | 2011-03-15 | 2011-09-14 | 西安理工大学 | Method for detecting screen dot of measurement and control strip based on machine vision |
| CN102183224B (en) * | 2011-03-15 | 2013-03-13 | 西安理工大学 | Method for detecting screen dot of measurement and control strip based on machine vision |
| CN104943358A (en) * | 2014-03-27 | 2015-09-30 | 北大方正集团有限公司 | Generation method and device for printing machine characteristic curve |
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