打印機(jī)外文翻譯

1、畢業(yè)設(shè)計(jì)/論文外 文 文 獻(xiàn) 翻 譯系 別 信息科學(xué)與技術(shù)系 專 業(yè) 班 級(jí) 通信工程0601班 姓 名 張 新 忠 評(píng) 分 指 導(dǎo) 教 師 陳 青 華中科技大學(xué)武昌分校2010 年3 月奧普蒂化的光譜紐格伯爾模型打印機(jī)特性摘要一個(gè)比色打印機(jī)需以其注入的一組油墨，預(yù)測(cè)由此產(chǎn)生的印刷顏色，通過反射或刺激值指定。該紐格伯爾模式已被廣泛用于預(yù)測(cè)的半色調(diào)彩色打印機(jī)色反應(yīng)。本文是介紹和比較優(yōu)化紐格伯爾模型的技術(shù)。這些措施包括尼爾森因素的優(yōu)化，這歸因于光的散射及估計(jì)該點(diǎn)區(qū)域并擴(kuò)展到精確位置的功能。一種新的技術(shù)描述了優(yōu)化紐格伯爾初選使用加權(quán)譜回歸。實(shí)驗(yàn)結(jié)果提出了它使用兩個(gè)半色調(diào)屏幕：隨機(jī)靜電打印機(jī)或旋轉(zhuǎn)點(diǎn)，

2、和互聯(lián)網(wǎng)上點(diǎn)屏幕。使用尤爾一尼爾森因子，細(xì)微的的框架，并使譜回歸模型的準(zhǔn)確度大大提高。1引言 比色打印機(jī)特性要求是建立在信號(hào)的輸入到打印機(jī)和由此產(chǎn)生的印刷顏色的色度測(cè)量的關(guān)系上的。這種關(guān)系，我們稱之為打印機(jī)特性的功能，往往是得到了印刷和測(cè)量補(bǔ)丁的色彩大量運(yùn)用了一些在已知的樣本的測(cè)量插值。另一種方法近似于用打印機(jī)型號(hào)的特征函數(shù)。試圖模擬打印機(jī)經(jīng)常會(huì)產(chǎn)生有價(jià)值的直覺的基本物理過程，它在光，色彩和紙之間產(chǎn)生復(fù)雜的相互作用。模型的實(shí)際優(yōu)點(diǎn)是打印機(jī)可以實(shí)現(xiàn)定性并相對(duì)較少的測(cè)量。打印機(jī)的模型精度顯然取決于模型中的假設(shè)是否正確。該紐格伯爾模型已廣泛用于二進(jìn)制模式的彩色打印機(jī)并可采用各種色調(diào)屏幕。原始模型實(shí)質(zhì)

3、上是Murray-Davies equation（用于預(yù)測(cè)灰度反射）的色彩方法。打印機(jī)字的顏色由紅綠藍(lán)（RGB）三色組合，預(yù)計(jì)作為對(duì)固體套印的RGB值加權(quán)平均印刷；青色，品紅和黃色的印刷，由地區(qū)覆蓋范圍相對(duì)點(diǎn)的權(quán)重決定。在這里，R，G，B可能被認(rèn)為是從印刷補(bǔ)丁反射光，通過3個(gè)已知光譜靈敏度的職能通過寬帶過濾器，超過估計(jì)所有在五個(gè)可見光波長(zhǎng)范圍內(nèi)的方法，從該地區(qū)的覆蓋范圍數(shù)字輸入色調(diào)，包括一些直接測(cè)量和計(jì)算的結(jié)合。請(qǐng)注意，盡管這種模式提供設(shè)備值（CMY）的特征函數(shù)（三原色）色值，它是從色值到設(shè)備空間，最終是為了尋求色彩再現(xiàn)逆映射。幾位研究人員討論了反相的紐格伯爾方程。這個(gè)反演問題是一個(gè)非線性問題

4、，可以解決在三個(gè)輸入著色劑的情形C，M，Y，通過迭代方法。當(dāng)著色劑數(shù)量超過3，問題就變得病態(tài)數(shù)著色劑組合可以導(dǎo)致生成相同的測(cè)量顏色。在這項(xiàng)工作中，只有前進(jìn)定性問題的審查。筆者認(rèn)為，一旦提出一個(gè)精確的模型，樣品的高密度，導(dǎo)出等多層面的擬合和插值技術(shù)可以很容易被用來(lái)顛倒模式。 各種方法已經(jīng)被提出了提高原紐格伯爾方程的準(zhǔn)確性。一個(gè)重要的現(xiàn)象，不占原模型，光散射的文件內(nèi)。Yule and Nielsen 通過模型中的一個(gè)額外的參數(shù)方程紐格伯爾這種效果。其他研究人員提出了在之間的透射模式和一紙點(diǎn)擴(kuò)散函數(shù)（PSF）的回旋空間光散射的形式更復(fù)雜的模型。尼爾森參數(shù)不明確的空間變化之間的相互作用光紙帳戶，有人建

5、議由魯克德舍爾和豪澤，一個(gè)簡(jiǎn)單的關(guān)系可能與這個(gè)簡(jiǎn)單的模型和滌綸短纖存在的模型。維賈諾表明，而不是在紐格伯爾方程形式的收益率更高的精度寬帶頻譜。這一發(fā)現(xiàn)證實(shí)了作者。 Engeldrum表明，無(wú)論是紙張和圓點(diǎn)的顏色相對(duì)點(diǎn)區(qū)域覆蓋范圍內(nèi)的功能，并延長(zhǎng)了紐格伯爾模型交代。利用該紐格伯爾方程的幾何解釋，開發(fā)了蜂窩Hueberger盧哥貝爾模式，即除固體套印顏色來(lái)計(jì)算最終輸出的顏色。蜂窩技術(shù)將被視為在本文件。從德米歇爾的假設(shè)出發(fā)點(diǎn)區(qū)域覆蓋范圍內(nèi)，并用序列二次規(guī)劃方法來(lái)估計(jì)這些參數(shù)。探討了波長(zhǎng)依賴尤爾使用尼爾森的因素。 在這項(xiàng)工作中采取的做法是，以符合理想打印機(jī)的紐格伯爾模型的基本形式，并提供優(yōu)化模型的參數(shù)

6、，以便更好地適應(yīng)實(shí)際打印機(jī)的特性的數(shù)學(xué)技術(shù)。因此，該模型簡(jiǎn)單保留，而其精度提高。優(yōu)化的圣誕-尼爾森因素，技術(shù)點(diǎn)區(qū)域功能，細(xì)胞模型已被提交會(huì)議的出版物上發(fā)表。本文介紹這些技術(shù)在一個(gè)比較一致的框架。此外，由在最近的一次會(huì)議報(bào)告的作者提出譜回歸的新方法，更詳細(xì)。實(shí)驗(yàn)結(jié)果提出了兩種類型的半色調(diào)屏幕：隨機(jī)或旋轉(zhuǎn)點(diǎn)，和互聯(lián)網(wǎng)上點(diǎn)屏幕上。 2紐格伯爾混合模型。二進(jìn)制打印機(jī)，一個(gè)多種顏色的渲染，是通過不同的組合達(dá)到點(diǎn)著色劑的主要地區(qū)覆蓋范圍。在紐格伯爾方程'預(yù)測(cè)從任意作為一種已知的基礎(chǔ)上為2n的色彩，光譜反射加權(quán)平均印刷補(bǔ)丁的平均光譜反射率，其中N是系統(tǒng)著色劑數(shù)量。在這項(xiàng)工作中的N = 3 CMY打印

7、機(jī)案件將用來(lái)描述各種模型。方程很容易推廣到N著色劑，而事實(shí)上，青色，洋紅色，黃色，黑色（CMYK）打印機(jī)將在實(shí)驗(yàn)結(jié)果中。對(duì)于CMY打印機(jī)，有8個(gè)的基礎(chǔ)上的顏色，這是白皮書（寬）和1，2和3純色覆蓋（即0和C，男，y的100的組合），這些基礎(chǔ)色將稱為紐格伯爾初選。在原來(lái)的紐格伯爾方程，預(yù)測(cè)的顏色是由三個(gè)寬帶代表短期，中期反射和電磁波譜的長(zhǎng)波長(zhǎng)部分指定。在這項(xiàng)工作中，窄帶反射光譜住宅（十）使用，而不是他們的寬帶同行，因?yàn)榍罢咭话闶找媛矢叩臏?zhǔn)確性。3結(jié)論 本文幾個(gè)打印機(jī)的紐格伯爾方程的模型已被描述和比較。一種新的技術(shù)已提出了優(yōu)化光譜紐格伯爾初選使用最小二乘回歸。提供各種型號(hào)的復(fù)雜性和精確度之間不同

8、的權(quán)衡。表1總結(jié)了在測(cè)量數(shù)量而言，這些權(quán)衡需要制定出一個(gè)給定的模式和結(jié)果的準(zhǔn)確性。一般來(lái)說(shuō)，模型的準(zhǔn)確度是成正比的測(cè)量數(shù)目，但人們可以方便地識(shí)別報(bào)酬遞減的情況。產(chǎn)生的巨大收益來(lái)自使用尤爾一尼爾森改正，并可以在細(xì)胞框架或全球譜回歸模型。測(cè)量的數(shù)目增加的細(xì)胞模型與細(xì)胞數(shù)量成倍的要求，同時(shí)在準(zhǔn)確增益減小。在34 = 81初選的情況常常是一個(gè)可以接受的折衷。在當(dāng)?shù)?，在?jì)算成本的大幅增加加權(quán)回歸結(jié)果（未顯示在表1），在沒有獲得準(zhǔn)確對(duì)全球回歸。 在執(zhí)行回歸的數(shù)學(xué)解釋是，它提供了一個(gè)自由的模式（即初選額外的程度），因此適合優(yōu)越的經(jīng)驗(yàn)數(shù)據(jù)。從初選的光譜，如無(wú)花果，陰謀的研究。 10和11，已經(jīng)從沒有測(cè)量，觀察

9、到的趨勢(shì)回歸職能。因此，很難物理意義重視對(duì)這些陰謀，除了指出，在選定的樣本良好的線性回歸可能會(huì)導(dǎo)致的光譜測(cè)量噪聲平均，從而得到更強(qiáng)大的預(yù)測(cè)。這項(xiàng)工作提出了一些進(jìn)一步的擴(kuò)展。譜回歸應(yīng)用于蜂窩架構(gòu)可能會(huì)導(dǎo)致沒有額外的提高測(cè)量精度。阿譜初選的聯(lián)合優(yōu)化，點(diǎn)區(qū)域功能和尤爾一尼爾森因素可能導(dǎo)致對(duì)其中n因素是單獨(dú)優(yōu)化目前的做法更好的結(jié)果。這是身體有理由認(rèn)為在光散射波長(zhǎng)基板依賴，因此一個(gè)譜回歸模型，支持n是X的函數(shù)可能會(huì)導(dǎo)致更準(zhǔn)確的模型的擴(kuò)展。然而，重要的是銘記之間的物理模型的復(fù)雜性和準(zhǔn)確性實(shí)現(xiàn)權(quán)衡始終牢記實(shí)際打印系統(tǒng)。最后，這將是值得研究的印刷技術(shù)比其他如靜電復(fù)印，噴墨機(jī)，膠印機(jī)等更具有效性。Opti iz

10、ation of the spectral Neugebauer model for printer characterizationAbstractA colorimetric printer model takes as its input a set of ink values and predicts the resulting printed color, as specified by re?flectance or tristimulus values. The Neugebauer model has been widely used to predict the colori

11、metric response of halftone color printers. In this paper, techniques for optimizing the Neugebauer model are presented and compared. These include optimization of the Yule-Nielsen factor that accounts for light scattering in the pa?per, estimation of the dot area functions, and extension to a cellu

12、lar model. A new technique is described for optimizing the Neugebauer primaries using weighted spectral regression. Experimental results are presented for xerographic printers using two halftone screens: the random or rotated dot, and the dot-on-dot screen. Use of the Yule-Nielsen factor, the cellul

13、ar framework, and spectral regression considerably increase model accuracy. ? 1999 SPIE and 1S&T. 1 IntroductionColor printer characterization requires that a relationship be established between the input signals to the printer and the colorimetric measurements of the resulting printed colors. T

14、his relationship, which we call the printer characterization function, is often obtained by printing and measuring a large number of color patches and applying some interpo?lation among the measurements at the known samples. An alternative approach is to approximate the characterization function wit

15、h a printer model. An attempt to model the printer often yields valuable intuition about the underlying physical process, which constitutes complex interactions between the light, colorant, and paper. A practical advan?tage of modeling is that the printer characterization can be achieved with a rela

16、tively small number of measurements. The accuracy of the printer model clearly depends on the validity of the assumptions in the model.The Neugebauer model has been widely used to model binary color printers employing various halftone screens. The original model is essentially an extension of the Mu

17、rray-Davies equation2 (used for predicting grayscale re?flectance) to the color case. The color of a print, in red?green-blue (RGB) coordinates, is predicted as a weighted average of the RGB values of the solid overprints of the three printing primaries, cyan, magenta, and yellow (C, M, Y), where th

18、e weights are determined by the relative dot area coverages c, m, y constituting the print. Here, R, G, B may be thought of as the reflected light from the printed patch, passed through three broadband filters with known spectral sensitivity functions, and summed over all wave?lengths in the visible

19、 range V. Methods for estimating dot area coverages from the digital input values to the halftone include some combination of direct measurement and cal?culation.Note that while the model provides the characterization function from device values (CMY) to colorimetric values (RGB), it is the inverse

20、mapping from colorimetric to de?vice space that is ultimately sought for color reproduction. Several researchers have addressed the problem of invert?ing the Neugebauer equations.3-6 The inversion is a nonlin?ear problem that can be solved, in the case of three input colorants C, M, Y, by iterative

21、approaches. When the num?ber of colorants exceeds three, the problem becomes ill-posed, as several colorant combinations can result in the same measured color. In this work, only the forward char?acterization problem is considered. It is the author's opin?ion that once a sufficiently dense sampl

22、ing of an accurate forward model is derived, other multidimensional fitting and interpolation techniques7?8 can easily be used to invert the model.Various methods have been proposed for improving the accuracy of the original Neugebauer equations. An impor?tant phenomenon not accounted for in the ori

23、ginal model is that of light scattering within the paper. Yule and Nielsen9 modeled this effect via an additional parameter in the Neu?gebauer equations. Other researchers10-12 have proposed more sophisticated models for light scattering in the form of a spatial convolution between the transmittance

24、 pattern and a paper point spread function (PSF). While the Yule-Nielsen parameter does not explicitly account for spatially varying interactions between light and paper, it has been suggested by Ruckdeschel and Hauser13 that a simple rela?tionship may exist between this simple model and the PSF bas

25、ed models. Viggiano14,15 demonstrated that working with the spectral rather than the broadband form of the Neugebauer equations yields higher accuracy. This finding has been confirmed by the author.16 Engeldrum et a/.17 .I' showed that the colors of both the paper and the dots are functions of t

26、he relative dot area coverages, and extended the Neugebauer model to account for this. Utilizing the geometric interpretation of the Neugebauer equations, Hueberger19 developed the cellular Neugebauer model, where colors in addition to the solid overprints are used to calculate the final output colo

27、r. The cellular technique will be considered in this paper. Lee et al.20 departed from the Demichel assumptions on dot area coverages, and used a sequential quadratic programming method to estimate these parameters. Hua and Huang21 and Iino and Bems22." ex?plored the use of a wavelength-depende

28、nt YuleNielsen factor.The approach taken in this work is to conform to the basic form of the Neugebauer model for an ideal printer, and to offer mathematical techniques for optimizing the parameters of the model to better fit the characteristics of real printers. Thus the simplicity of the model is

29、retained, while its accuracy is improved. Techniques for optimizing the YuleNielsen factor, dot area functions, and cellular model have been published in previous conference publica?tions by the author.16'24 In this paper, these techniques are presented and compared in a coherent framework. In a

30、ddi?tion, a new method of spectral regression proposed by the author in a recent conference report25 is presented in greater detail. Experimental results are presented for two types of halftone screens: the random or rotated dot, and the dot-on?dot screen.The paper is organized as follows. In Sec. 2

31、, the Neuge?bauer mixing model is briefly introduced, and is applied to the two types of halftone configurations. The light scatter?ing problem and YuleNielsen correction are described in Sec. 3. Methods for calculating the dot area functions are described in Sec. 4, and extensions to the cellular f

32、rame?work are presented in Sec. 5. A spectral regression tech?nique is described in Sec. 6, where the Neugebauer prima?ries are themselves treated as parameters to be optimized. Experimental results are presented in Sec. 7, and conclud?ing remarks are collected in Sec. 8.2 Neugebauer Mixing Modelor

33、a binary printer, the rendering of a multitude of colors is achieved through combinations of varying dot area cov?erages of the primary colorants. The Neugebauer equations' predict the average spectral reflectance from an arbitrary printed patch as a weighted average of the spectral reflectances

34、 of 2N known basis colors, where N is the num?ber of system colorants. In this work, the case of N=3 for CMY printers will be used to describe the various models. The equations are easily generalized to N colorants; and indeed, cyanmagentayellowblack (CMYK) printers will be included in the experimen

35、tal results.2.3 Effect of Screen DesignOne of the fundamental factors that affects model accuracy is the frequency of the halftone screen.".28 The ideal model assumes that the dots are rectangular in cross section, and hence result in a binary absorption profile as a function of spatial locatio

36、n. In reality, dots have soft transitions from regions with full ink to regions with no ink. If the halftone screen frequency is relatively low, or a clustered dot is used, the relative area of the paper covered by the transition pected to be relatively accurate. On the other hand, if the screen fre

37、quency is high, or a dispersed dot is used (as is the case with a Bayer screen or error diffusion), then a large fraction of the paper is covered by transitory regions, and the model breaks down. The corrections discussed in Sec. 3 partially account for soft transitions; nevertheless, the reliabilit

38、y of the model has been seen to be greatest with clus?tered dot screens in the range of 300-400 halftone dots per inch.8 ConclusionsIn this paper, several printer models based on the Neuge?bauer equations have been described and compared. A new technique has been proposed for optimizing the spectral

39、 Neugebauer primaries using least squares regression. The various models offer different tradeoffs between complex?ity and accuracy. Table 1 summarizes these tradeoffs in terms of the number of measurements required to derive a given model and the resulting accuracy. Generally, model accuracy is pro

40、portional to the number of measurements; however one can easily identify cases of diminishing re?turns. The significant gains come from using the Yule-Nielsen correction, and either the cellular framework or the global spectral regression model. The number of measure?ments required in the cellular m

41、odel increases exponen?tially with the number of cells, while the gain in accuracy diminishes. The case of 34=81 primaries is often an ac?ceptable tradeoff. The locally weighted regression results in a significant increase in computational cost (not shown in Table 1), with little gain in accuracy over the global regres?sion.The mathematical interpretation of performing regres?sion is that it affords an extra degree of freedom in