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	Knowledge itself is power. - Sir Francis Bacon, of heresies
	ANNEX 3: CROSS REFERENCE OF COLOR SHIFT & COLOR MODELS 各 類輸出色彩偏差參考數據表及常用色 彩模式簡介 - last updated on Aug. 10, 2005 - Index - Click the following bookmarks to jump to the topic you're interested - 3.1 CROSS REFERENCE OF COLOR SHIFT 各類輸出色彩偏差 3.2 COLOR MODELS 色 彩模式 3.2.1 Color Gamuts and Color Models  色彩空間及色彩模式 3.2.1.1 RGB Color Model 3.2.1.2 CMYK Color Model 3.2.1.2.1 Working Principle of CMYK Color Model 工作原理 3.2.1.2.2 Application in Full Color Offset Printing 印刷應用  i Color Separation and Screen Angle 分色及網角  ii Combination of Color 色彩之組合  iii Screen Repetition And Quality of Printing 網線密度及印刷質素 3.2.1.3 HSB Color Model 3.2.1.4 PMS Color Model 3.2.2 Color Models and Conversion 彩色模式之轉換: 3.2.3 Color Depth and Output Resolution 色深與輸出精度: 3.3 Color Swatch 色標 3.1 CROSS REFERENCE OF COLOR SHIFT 各類輸出色彩偏差 The following figures are only estimations based on empirical experience instead of any well-established industrial standard. There is no warranty of any kind, either express or implied, regarding the accuracy, reliability or correctness of the data listed below. Nevertheless, they may be regarded as a reference of our commitment in printing service to our customers. Presumption: For those artworks presented in the form of soft copy, it is supposed that they are ripped by the same software/hardware rip without changing the color mode in different batch print jobs.  For those artworks presented in the form of film/hard copy, it is supposed that the same printing machines, ink and media are used in different batch print jobs.  The final printout should be viewed under the same lamination condition.. CMYK color model, except for monitors and silk screen printing, is employed and the panetone processing color guide or equivalent serves as a common reference of standard. - last updated on Aug. 10, 2005 VGA/XGA CRT Monitor (RGB) 720dpi or lower Inkjet Printer (CMYK) Dye-sub Proof, 1440dpi+ Inkjet Printer (CMYK) 1200dpi Color Laser  Proof (CMYK) CMYK film Press Proof (CMYK) CMYK offset printing (CMYK) Bromide Foto Paper, Lambda (CMYK/RGB) Silk-screen Printing (Solid Color) VGA/XGA CRT Monitor (RGB) +/- 5% 720dpi or lower Inkjet Printer +/- 5% +/- 20% +/- 20% +/- 20% +/- 20% +/- 20% +/- 20% Dye-sub Proof/ 1440dpi+ Inkjet Printer +/- 5% +/- 10% +/- 10% +/- 10% +/- 15% +/- 15% 1200 dpi Color Laser  Proof +/- 10% +/- 10% +/- 10% +/- 15% +/- 15% CMYK film Press Proof +/- 5% +/- 5% +/- 15% +/- 15% CMYK offset printing +/- 5% +/- 15% +/- 15% Bromide Foto Paper, Lambda +/- 10% +/- 15% Silk-screen Printing +/- 10% 3.2 COLOR MODELS 色彩模式 3.2.1 Color Gamuts: By definition, color gamuts means the scope of color which can be reproduced using a certain output technology. As naked human eye is sensitive to 3 primary visible lights, namely Red, Green And Blue, output devices using RGB model is capable of displaying the greatest extent of color. However, it is applicable to light emitting devices like TV sets or Monitors only. Click the image for larger image The common printing methods using CMYK color model reproduces colors by screening the light reflected from either the base on which the colors are printed or the pigment of color itself. The color gamuts is smaller than RGB model due to the loss and distortion in the process of reflection and filtration except for some PMS colors which can reflect a special section of the color spectrum that even goes beyond the color gamuts of RGB model.  The following diagram shows how color image is reproduce using CMYK color separation method: 3.2.1.1 RGB Color Model: RGB color is applicable to light emission devices like TV or monitor which reproduce the color by mixing matrix of light emission dots in Red, Green and Blue together to form a specific color in human naked eyes.  It is called additive color because all colors are the mixture of these 3 primary colors. It also produces the greatest color gamut among all available color models except  PMS color like gold, silver or some specific material. Experienced Artists should be careful in using RGB model in the process of creation or it would be misleading to their clients and result in dispute over the color correctness of printed matter with respect to the preview image on monitor. Click the above image for more color swatch with illustration of color models in PDF format. 3.2.1.2 CMYK Color Model (Subtractive Color): 3.2.1.2.1 Working Principle of CMYK Color Model  工作原理: Printed matter cannot emit light; it reflect light from luminous light source only.  A traditional painter may apply different colors on his palette to his canvas or paper with paint brush. Nevertheless, printing too many colors on media is not feasible from both the economic and  technical point of view. The current CMYK printing method use subtractive color. All colors are reproduced by screening the light (supposed to be white) reflected from either the base on which the colors are printed. The Color pigment of the 4 process color, C,M,Y and K work as filter which "subtract" one primary color from the white light respectively. The following diagram illustrates how the system works.  Overlapping different color ink may screen away unwanted primary color from the reflected light. This method only reproduced a smaller color gamuts compared with RGB or PMS color model. Click the above image for more color swatch with illustration of color models in PDF format. 3.2.1.2.2 Application in Full Color Offset Printing 印刷應用 i. Color Separation and Screen Angle 分色及網角: In the process of full color offset printing, the color artwork must be output to color separation films of 4  chanels,  say C, M, Y and K. The film is either positive or negative in B/W only. The intensity of each color is represented by dotted lines arranged in specific angle, i.e. screen angle. The working of color separation is illustrated in the following diagram which simulate the combination of color dots under microscope. ii. Combination of Colors 色彩之組合: These film will be used for making the lithographic zinc plates which in turn transfer the color ink to the paper one by one. The overlapping of the color dots then reproduce a color image  of the original artwork. Under the nake eyes of human being, the combination of these color dots reproduces a ful color image looks almost the same as the original artwork. Most of the text book or even technical reference give little explanation to the use of screen  in offset printing. The reason is not too technical to be understood. In the first place, ink used for offset printing is not quite transparent like color glass filter. It reflects the light rather than letting it pass. Secondly, it is unlikely to print color ink of varied thickness to reproduced different tones  all at once like painting with brush in the process of high speed printing  even inks are transparent. However, for some  printing technology like dye sublimation or thermal wax transfer while the thickness of dye can be determined by the time of heat applied to it, the tone of  color is thus  reproduced by transparent  layers of CMYK  dye of varied intensity. iii. Screen Repetition and Quality of Printing 網線密度及印刷質素: It should be noted that the density of dot lines is positive related to the resolution of the printing. Therefore, upon the increase of line per inch (lpi)  or screen repetition, the quality of printing should be better supposing that the printing machine supports the resolution.  The following diagram shows how they look different under magnifier. Refer to 3.1 CROSS REFERENCE OF COLOR SHIFT 各類輸出色彩偏差 for more information on color shift and  Annex 5 for more informmation about resoultion of image and printing.    3.2.1.3 HSB Color Model: This model defines color by "Hue", "Saturation" and "Brightness". Hue represented by the relative location of  in the color wheel. For instance, if zero degree represent "Red", Magenta, Blue, Cyan, Green and Yellow are 60, 120, 180, 240, 300 respectively. Changing the Hue means shifting the color round the color wheel. The second property of color is saturation which refers to the intensity of color. It ranges from 0 (i.e. gray) to 255 (i.e. fully saturated color). The third property is brightness which represent the lightness or darkness of a color. As illustrated in a 3-dimensional model as shown in the diagram, the changes of the three properties of color are visualized by a column of color wheels. This color model is useful in tunning color temperature and brightness especially on TV or monitor. Click the image for larger image 3.1.2.4 PMS Color Model: Sometimes the CMYK process colors cannot match a specific color for demanding print job. Spot color will be used. The most renowned spot color system is Pantone™ Matching System (PMS), which is a trademark system of over thousand colors identified by a unique color code. Every color is a premixed ink according to the formula provided by the vendor of PMS. PMS  is also commonly used in screen printing  or transfer printing because the halftoning approach for offset printing is not possible for this printing technology except some advanced equipment like those used for printing label directly on CD or DVD surface.  3.2.2 Color Models and Conversion 彩色模式之轉換: In the absence of a common algorithm for the conversion of different color models, all digital artworks created for printing purpose should be converted into CMYK model before they are sent to output devices. A significant range of RGB colors are not printable as they go beyond the color gamuts of CMYK or PMS color model. If not otherwise specified, the conversion will be done using the software of "Adobe" including "Illustrator" or "Photoshop".  It should be noted that different vendors have their own conversion algorithm in converting non -cmyk colors into cmyk colors but none can be claimed the universal standard. 3.2.3 Color Depth and Output Resolution  The depth of color refers to the number of distinguishable colors that can be reproduced. The higher the resolution of output device, the more colors it can produce and so does the accuracy of the color with respect to the original artwork. A reasonable color shift should be acceptable and is not liable to any claim for non standard goods. Please refer to annex 5 for more information. 3.3 Color Swatch 色標 Some prominent printing solution vendor publish a series of color swatches as a standard reference guide for the printing industry. The most famous brand name product is the "Pantone" color guide series. However, our practical experience told us that even an artwork created in CMYK model could not be reproduced identically using different output devices. Unlike image setters, the current printers available in market manufactured by different  producer always print the color copy with their own emphasis or preference. It is always a disaster when using this hardcopy of artwork as a proof and quality control standard for the final product. To assist people in need of an impression about the discrepancy of color reproduction between their printing device and the standard color swatch, we created a "CMYK Electronic Color Swatch" in PDF format and post it on our web-site for all interested persons to download free of any charges. You may right click your mouse on the following image and save link target to your harddisk to get a free softcopy of "CMYK Electronic Color Swatch". Print the swatch using your own printing device and compare them to the standard color guide like Pantone Processing Color Guide".  Then you will have an idea about how far your printing device deviate from the offset printing machine. Click the above image for more color swatch with illustration of color models in PDF format. Note: All the brandnames mentioned above belong to their respective owners. Back to Customer Support Index  回到顧客支援目錄

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Our Committment to Creativity 我們對創新的理念

For more than two decades,  we've been working hard to achieve the seamless fusion of  old with new, east with west  and art with science. Neither a clumsy mixture nor  a simple crossover can satisfy us.  We've never thought that we 've really made it.  Yet we've tried our best to approach it without regret.

In this approximately 36sec promotion  trailer in  mpg-1 file of 4.3MB,  we not only show our committment to creative industry (Quicktime needed)., but also demonstrate a low cost production of mutimedia ad on the internet is simple and possible. More samples are available. Just click and check. 

在20年的歲月裡，我們曾努力不 懈地嘗試，揉合現代和傳統、東方和西方、藝 術和科技，我們不敢奢言成功、或滿足於簡單 的混合、以至笨拙的結合，但卻無悔追 尋這36秒的動畫, 表達我們對創作的理念, 也展示低成本創作之可能. 網頁內有更多我們的創作樣本.

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