3D打印立体着色方式与颜色再现特性研究.pdf

PRINTING AND DIGITAL MEDIA TECHNOLOGY STUDY Tol.229 No.2 2024.04印刷与数字媒体技术研究 2024年第2期（总第229期）RESEARCH PAPERS研究论文Research on Stereoscopic Coloring Method and Color Reproduction Characteristics of 3D Printing ZUO Shuai1,YAO Dan-yang1,WANG Li-ru1,CHEN Guang-xue1,2*(1.State Key Laboratory of Pulp and Paper Engineering,South China University of Technology,Guangzhou 510640,China;2.Huagong Liyan(Guangdong)New Material Technology Company Limited,Foshan 528000,China)Abstract Currently,the core elements of 3D printing technology are not only the construction of model shapes,but also higher precision in color reproduction.Due to differences in coloring methods,the color reproduction of 3D printed objects varies,thereby affecting the precision of color reproduction and analytical evaluation in 3D printing.Therefore,in this study,based on UV 3D printing,the printed models using three different coloring methods were designed including infill color mode and surface color mode(single-layer surface color mode and double-layer surface color mode).It investigated the impact of coloring methods and the number of color layers on the color reproduction quality of the surfaces of various colored 3D models,including an analysis of luminance,density,and color difference.The results showed that with the same number of layers,fewer color layers result in higher brightness,lower density,and smaller color deviation.This suggested that boundary coloring is superior to full-area coloring,and the fewer color layers on the surface,the better the reproduction effect.This study can provide the theoretical basis and support for the color reproduction in 3D printing.Key words Color 3D printing;Coloring method;Color reproduction;Color evaluation3D打印立体着色方式与颜色再现特性研究左 帅1，姚丹阳1，王俪儒1，陈广学1,2*(1.华南理工大学 制浆造纸工程国家重点实验室，广州 510640；2.华工丽颜(广东)新材料科技有限公司，佛山 528000)摘要 目前，3D打印技术的核心要素不仅在于模型的形状构建，对于颜色的精确再现也提出了更高的要求。由于着色方式不同，3D打印物体的颜色再现效果也会不同，从而对3D打印颜色精准再现和评价分析有一定的影响。因此，本研究基于UV 3D打印，设计并打印了三种不同着色方式的模型，分别是内填彩色模式和表层彩色模式（表面1层彩色模式，表面2层彩色模式），研究着色方式和层数对不同颜色的3D立体模型表面收稿日期：2023-06-25 修回日期：2023-09-18 *为通讯作者项目来源：国家自然基金面上项目(No.61973127)；广东省自然科学基金(No.2022A1515011416)本文引用格式：ZUO Shuai，YAO Dan-yang，WANG Li-ru，et al.Research on Stereoscopic Coloring Method and Color Reproduction Characteristics of 3D Printing J.Printing and Digital Media Technology Study，2024，(2)：54-65.2024年2期印刷与数字媒体技术研究（拼版）.indd 542024年2期印刷与数字媒体技术研究（拼版）.indd 542024/4/26 17:07:462024/4/26 17:07:4655研究论文ZUO Shuai et al:Research on Stereoscopic Coloring Method and Color Reproduction Characteristics of 3D Printing0 IntroductionWith the rapid advancement of technology,3D printing,as a form of additive manufacturing(AM),has gradually emerged as a significant technology in both industrial and research domains1.Distinct from traditional manufacturing methods,3D printing precisely constructs complex three-dimensional structures through the additive layering of materials,significantly expanding the potential within the manufacturing sector.Currently,it has found widespread application in diverse areas including medical,aerospace,bioengineering,creative and cultural industries,and heritage conservation2-7.As its application scope continues to broaden,3D printing technology is no longer confined to merely constructing model shapes.It now demands a higher fidelity in color reproduction as well.Color,being one of the most intuitive and expressive attributes of an objects surface,plays a crucial role in enhancing the visual appeal and practical value of 3D printed products8-10.The advent of color 3D printing technology has greatly expanded the application scope and creative potential of 3D printing,sparking widespread research interest in recent years.9,11-12.These research outcomes are not only demonstrated in the diversity of technical equipment and material choices but also in significant advancements in quality control and the push towards standardization13-15.Since 2014,the leading international 3D printing equipment manufacturers have successively launched a variety of color 3D printer models,such as the ProJet series powder-based color 3D printers by 3D-Systems,Stratasys series resin-based color 3D printers by Stratasys.Moreover,through detailed experimental research,Li et al16 successfully mapped the relationship curves between the thickness,hue,brightness,saturation,and color difference of Polyjet 3D printing,providing optimized strategies for color reproduction in color 3D printing technology.Concurrently,Yuan et al17 conducted in-depth discussions on the quality of color reproduction in color 3D printing,with a particular focus on the attributes of color layers,such as thickness and sequence,revealing the significant impact of these factors on color effects,thereby proposing new insights for enhancing print quality.However,despite these important findings,theoretical research on the coloring methods in color 3D printing remains insufficient and requires further in-depth exploration to enrich the research foundation and practical applications in this field.Different coloring methods impact the brightness and color reproduction of printed objects differently,and they also consume varying amounts of color pigments,which in turn influences the printing costs.Hence,in this study,three distinct coloring approaches were designed with UV 3D printing technology.Simultaneously,the variables such as color,coloring method,and the number of layers were considered to investigate their effects on the color reproduction of the surface of differently colored 3D stereo models.颜色再现的影响，并对明度、密度和色差进行分析总结。结果显示，相同层数下，彩色层越少，则明度越大，密度和色差越小。这表明边界着色方式优于全域着色方式，并且表面彩色层越少，再现效果也越好。本研究可为三维打印中的彩色复制提供理论依据和支持。关键词 彩色3D打印；着色方式；颜色再现；颜色评价中图分类号 TS805.4文献标识码 A文章编号 2097-2474(2024)02-54-12DOI 10.19370/10-1886/ts.2024.02.0062024年2期印刷与数字媒体技术研究（拼版）.indd 552024年2期印刷与数字媒体技术研究（拼版）.indd 552024/4/26 17:07:462024/4/26 17:07:4656印刷与数字媒体技术研究2024年第2期（总第229期）Furthermore,this study included a comprehensive analysis of luminance,density,and color difference to provide theoretical basis and support for color reproduction in 3D printing.1 Experimental Methods1.1 Overall Model DesignIn this study,the experimental model was designed based on the 3D printing of the full-area coloring and boundary coloring two ways to simulate the 3D printing reproduction effect.Fig.1a was the 3D printing of the full-area coloring model,Fig.1b was the 3D printing of the printed boundary coloring model(3D object outer surface coloring,the interior filled with white).To explored the color reproduction effect of the side surface layer of different coloring methods,the side surface part of the design model was simulated with the full-area coloring and boundary coloring methods,three different ink coloring modes were designed with seven colors.The colors included Cyan(C),Magenta(M),Yellow(Y),Black(K),Red(R),Green(G)and Blue(B).The ink coloring models were the in-fill color model and the surface color models(single-layer surface color model,double-layer surface color model).In this study,the in-fill color mode represented full-area coloring,while the surface color models represented boundary coloring.Each model can be uniformly written in the form of Xn-Y-Wm,with X denoting the ink coloring mode,n denoting the number of color layers(n was a positive integer from 1 to 10),where the in-fill color mode was denoted by A,the surface color mode was denoted by F(single-layer surface color mode was denoted by F1,and the double-layer surface color mode was denoted by F2),Y denoted the color,W denoted the white ink,and m denoted the white ink layer(m was a positive integer from 1 to 9 positive integers).For example,A6-C denoted the in-fill 6-layer cyan model,and F1-C-W5 denoted the single-layer cyan surface and 5-layer white model.O denoted the initial model in the software.Fig.1a was the A10-C model,and Fig.1b was the F1-C-W9 model and the F2-C-W8 model.a.Full-area coloring method(A10-C model)b.Boundary coloring method(F1-C-W9 and F2-C-W8)A10-CF1-C-W9F2-C-W8Fig.1 Coloring methods schematic图1 着色方式示意图1.2 In-fill Color Model DesignFirstly,with Adobe Illustrator 2020 software,a new 10 cm10 cm canva was created,using the ellipse tool in the first layer to drew 10 circles with a radius of 1.65 cm,arranged in accordance with the 43 way,the color fill was 80%cyan.On the second layer,drew 9 circles with a radius of 1.65 cm,arranged in a 33 manner,and their location coincided with the location of the circle in the upper left of the first layer,and the color fill was 80%cyan.On the third layer,8 circles with a radius of 1.65 cm were drawn,arranged in a 33 pattern so that they coincided with the top left circle in the previous layer,all with a color fill was 80%cyan.The rest of the layers will follow suit,and when the cyan model was finished,the other 6 colors will be designed according to their design steps.1.3 Surface Color Model DesignThe process for designing the model with 1 layer of color ink and m layers of white ink(where m is 1 out of 9 integers)was as follows.Firstly,Adobe Illustrator 2020 software was opened,and a new 10 cm10 cm 2024年2期印刷与数字媒体技术研究（拼版）.indd 562024年2期印刷与数字媒体技术研究（拼版）.indd 562024/4/26 17:07:462024/4/26 17:07:4657研究论文ZUO Shuai et al:Research on Stereoscopic Coloring Method and Color Reproduction Characteristics of 3D Printingcanva was created.Using the ellipse tool in the first layer,9 circles with a radius of 1.65 cm were drawn,arranged in a 33 pattern,with the color fill set to white.On the second layer,8 circles with a radius of 1.65 cm were drawn,arranged in a 33 pattern,and their locations were made to coincide with the upper-left circle in the previous layer,with the color fill also set to white.Layers from 3 to 9 were designed following the same method.On the 10th layer,9 circles with a radius of 1.65 cm were drawn,arranged in a 33 manner,and their locations coincided with those of the circles in the first layer,and the color fill was 80%cyan.Finally,the other 6 colors were designed according to the cyan model design procedure.The surface for 2 layers of color ink,the bottom layer for m layers of white ink(m is 1 value of 8 integers)of the model design process was as follows.Adobe Illustrator 2020 software was first opened,and a new 10 cm10 cm canva was created.Using the ellipse tool in the first layer,8 circles with a radius of 1.65 cm were drawn,arranged in a 3 3 pattern,with the color fill being white.On the second layer,7 circles with a radius of 1.65 cm were drawn,arranged in a 33 manner,and their locations coincided with the upper-left circle in the previous layer,with the color fill also being white.Layers from 3 to 8 were designed according to the above method.On the 9th layer,8 circles with a radius of 1.65 cm were drawn,arranged in a 33 manner,and their locations coincided with those of the circles in the first layer,and the color fill was 80%cyan.On the 10th layer,drew 8 circles with a radius of 1.65 cm,arranged in a 33 manner,and their locations coincided with those of the circles in the first layer,and the color fill was 80%cyan.According to the design steps of the cyan model,the other 6 colors were designed sequentially.Color-specific parameter values were shown in Tab.1.1.4 Model Digital Processing and OutputAfter the above model was designed,a UV inkjet printer(Handtop HT2512)was used to print it out on a 10 cm10 cm acrylic board.The ink was Rigid Ink HX1-L1,starting from the first layer to the last layer according to the number of model layers.In total,there were 7 colors across 21 models.The output samples were left to dry for about 10 minutes.1.5 Date Acquisition and Characterization1.5.1 Acquisition of Density Data for 3D Solid Models After the output sample of the above 3D stereoscopic model had dried,the X-rite 500 series spectrophotometer(Parameters:measurement condition was M1,lighting source was D50,observer angle was 2)was used to measure the density value on the surface of the model.It was measured a total of 5 times,and the average value was taken.Density D calculation formula such as Formula(1).(1)where represents the light reflectance.1.5.2 Color Data Acquisition of the 3D Stereoscopic ModelAfter the output sample of the aforementioned 3D stereoscopic model had dried,the X-rite 500 series spectrophotometer was used on the surface of the model(Parameters:measurement condition was M1,lighting source was D50,observer angle was 2)to measure the L*a*b*value,taken the average value of 5 measurements in total.Calculation formula such as Formula(2).(2)where E*is the relative color difference,L*1,a*1,b*1 are the model surface color values,L*2,a*2,b*2 are the initial color values.Tab.1 Color parameters of the 3D stereo model表1 3D立体模型的颜色参数ColorParametersCMYKRGBL*66589537576133a*-2263-9157-5222b*-42-68105127-462024年2期印刷与数字媒体技术研究（拼版）.indd 572024年2期印刷与数字媒体技术研究（拼版）.indd 572024/4/26 17:07:472024/4/26 17:07:4758印刷与数字媒体技术研究2024年第2期（总第229期）2 Results and Discussion2.1 3D Stereoscopic Color Reproduction Effect in In-Fill Color ModeTab.2 showed the 3D stereoscopic surface color brightness values in the A model,and combined with Fig.2a,it was observed that apart from A-K,the other six colors experienced a decrease in surface color brightness with an increase in the number of stacked layers,eventually converging infinitely to a certain value.This indicated that with an increase in the number of color stacking layers,the absorption of color light on the ink layer increased and the reflectivity decreased,leading to a decrease in the surface color luminance of model A,while A-K showed an increase with the increase in the number of stacking layers.The surface color luminance of A-C,A-R,A-G,and A-B varied more significantly with the increase in the number of stacking layers.In contrast,the variations of A-M,A-Y,and A-K were smaller.Tab.2 Color luminance on the surface of 3D stereo models with different layers in A mode表2 A模式下不同层数的3D立体模型表面颜色明度ColorLayersCMYKRGBA142.6342.4862.4720.8641.2140.0123.73A235.8636.7260.949.3734.331.0913.49A332.535.4460.469.8132.2726.3110.86A429.9934.6259.8212.5231.1723.499.45A528.233.4358.5614.7729.9120.859.17A626.9833.6358.3715.9729.7519.139.06A725.7933.9757.8216.1728.8917.988.95A825.2333.4256.9618.9428.2816.79.92A924.9833.4757.0219.528.1415.4910.17A1024.3834.0256.9720.328.2315.199.96Fig.2b showed the 3D stereoscopic surface color density changes in the A model.Overall,except for A-C and A-K,the other five colors saw their surface color density gradually increase with the increase in d.3D stereo models in A-C,A-M,A-Y and A-Ka.Color luminance change on the surface of 3Dstereo models with different layers in A modec.Chromatic aberration change on the surface of 3Dstereo models with different layers in A modeb.Color density change on the surface of 3Dstereo models with different layers in A modeBGRKYMCA1 A2 A3 A4 A5 A6 A7 A8 A9A100.000.501.001.502.00BGRKYMCA1 A2 A3 A4 A5 A6 A7 A8 A9A100.0020.0040.0060.0080.00A-CA-MA-YA-K80.0060.0040.0020.000.00E*A1 A2 A3 A4 A5 A6 A7 A8 A9 A10CMYK