What are RGB and CMYK color samples? 3
How do the color samples work? 4
Tips for using the color samples 4
Printing the color samples 4
Color matching in Microsoft Office applications 5
Color matching in Adobe Illustrator and PhotoShop 5
For more information 6
HP Color LaserJet printers offer great color printing out of the box with a combination of automatic color features. Setting color options to automatic typically produces the best possible print quality for color documents.
However, for the more experienced professional who wants sophisticated color tools, the printer provides carefully designed and tested color tables to offer smooth, accurate color reproduction of all printable colors. The process of matching printer output color to a computer screen is quite complex because printers and computer monitors use different methods of producing color. Monitors display colors by light pixels using a Red, Green, and Blue (RGB) color process, but printers print colors using a Cyan, Magenta, Yellow, and Black (CMYK) process. Several factors can influence a user’s ability to match printed colors to those on a monitor. These factors include:
Printer colorants (inks or toners, for example)
Printing process (inkjet, press, or laser technology, for example)
Personal differences in perception of color
Computer operating system
Video cards and drivers
Operating environment (humidity for example)
Keep the above factors in mind when colors on a screen do not match printed colors exactly. HP Color Samples for RGB or Color Samples for CMYK offer a method to obtain a desired color from a specific printer. Color samples are currently available for HP Color LaserJet 4650, 4700, and 5500 series printers and will be available for most future HP Color LaserJet products. Figure 1 illustrates a color samples document.
To provide precise color matching for printed output, HP offers comprehensive color samples for HP Color LaserJet printers. Color samples allow experienced users to get the colors they want from a variety of software applications regardless of the print media.
What are RGB and CMYK color samples?
P Color Samples for RGB or Color Samples for CMYK can be printed either directly from the print driver or by printing a special PDF. The samples printed on your printer with the paper type, toner, and consumables you plan to use will provide the best example of what a given color value will look like when printed. This is most useful in the case of logos and other spot colors for which color matching is essential. Figure 2 illustrates color samples for RGB.
Standard Red Blue Green (sRGB) is a world-wide color standard originally developed by HP and Microsoft® as a common color language for monitors, input devices (scanners and digital cameras), and output devices (printers and plotters). It is the default color space used for HP products, Microsoft operating systems, the World Wide Web, and most
office software sold today.
The latest versions of Adobe® PhotoShop®, Microsoft Office, and many other applications use sRGB to communicate color. Most importantly, as the default color space in Microsoft operating systems, sRGB has gained broad adoption as a means to exchange color information between applications and devices using a common definition that ensures typical users will experience greatly improved color matching. The sRGB standard improves the ability to match colors between the printer, the PC monitor, and other input devices (scanners and digital cameras) automatically, without the need to become a color expert.
he HP Color Samples for RGB contains a cover sheet, 19 pages of RGB samples, and a page with the Microsoft Office Basic Colors. The cover sheet contains a brief description and a legend showing the scaled contents of the following pages. The 19 RGB sample pages are ordered by hue: magenta, red, orange, etc. Within a page hue, saturation and brightness are varied, providing a wide range of colors to select from. The last page contains the Microsoft Office Basic Colors. These colors are arranged similarly to the color menu in a Microsoft Office application, such as Word or PowerPoint. Figure 3 illustrates the Microsoft Office table.
CMYK are the inks used by a printing press. The process is often called four-color printing. CMYK data files are typically used by and originate from graphic arts (printing and publishing) environments. The printer will accept CMYK colors through the HP postscript level 3 emulation print driver. The printer color-rendering of CMYK is designed to provide rich, saturated colors for text and graphics. HP Color Samples of CMYK are similar to the RGB except the last page, 20/20, has simple color ramps of primary and secondary colors, as illustrated in figure 4.
How do the color samples work?
Printing from the printer control panel uses the default color rendering. For RGB this is sRGB; for CMYK this is a SWOP-like rendering. If you do not use the default settings in the driver Color tab, download and print using the PDF through the driver with the customized settings. (See “Printing the color samples“ below for more information.) If color management is used in the typical workflow, applications, or in the operating system, print the PDF file using the same color management path.
Note Changing the halftones or neutral axis treatment will affect both RGB and CMYK printing. Changing the RGB color settings will affect the RGB samples. Changing the CMYK ink emulation settings will affect the CMYK samples.
Tips for using the color samples
Print the samples on the target paper type. Paper does affect color appearance.
Do not duplex print the samples.
For CMYK from the PDF, use the same driver consistently. It is best to use the HP postscript level 3 emulation driver. Many applications and operating systems allow CMYK to be printed with the PCL driver, but they inconsistently convert the color to RGB.
The printer should be in normal operating condition for your environment before you print the color samples. Use a new printer or a printer that has sat idle for a number of hours for a short time first, and make sure that supplies aren’t close to running out.
The sample pages may need to be re-printed periodically.
The sample book applies only to the printer it was printed on.
Printing the color samples
You can print samples from the printer’s control panel. This will print a cover sheet followed by 20 pages of samples. To print the color samples:
Press MENU to enter the MENUS.
Use the arrow keys to highlight INFORMATION. Press select.
Use the arrow keys to highlight PRINT CMYK SAMPLES or PRINT RGB SAMPLES. Press select.
Samples can also be printed by going to www.hp.com/support/lj4700 and downloading the sample PDF files. Print the PDF files using Adobe Acrobat Reader or other PDF-compatible applications.
Note Colors may vary depending on paper type and the software application used. Obtain a more accurate color output by printing color palette samples from the desired application, when possible. This allows the colors to be defined and processed by the application itself, so it can produce a more accurate representation of the final print product.
Color matching in Microsoft Office applications
Figure 1. Changing RGB values in Microsoft Office application
o get a specific, desired color for something such as a company logo, select the color sample that is the closest match to the desired color. If, for example, the desired color is red, compare the printed red (RGB values 255, 0, 0) to the color samples. If a more orange red is desired, look up the color in the samples. The RGB values 255 (R), 53 (G), 0 (B) or (255, 53, 0) result in an orange red and may match the desired color. In the Microsoft Office application, the object color can be edited and the color value of (255, 0, 0) can be modified to (255, 53, 0) to result in the desired orange red color, as illustrated below.
The last page of the RGB Color Samples shows that Microsoft Office basic colors can be used as a reference for how each of the basic colors will be rendered by the printer. Due to differences in the monitor gamut and the printer gamut, it is impossible to give exact matches for all monitor-displayed colors. Consider the color green, for example. Observe the green on the monitor; it is very colorful and bright. The printer is not capable of printing such a color. On the other hand, the printer is capable of printing a colorful, dark cyan color that the monitor cannot display. To see what color is printed for each of the Microsoft Office
basic colors, reference the samples.
Color matching in Adobe Illustrator and PhotoShop
ewer versions of Illustrator and PhotoShop allow direct importing of the PDF into the application. This allows colors to be defined and processed by Illustrator or PhotoShop, creating a more accurate representation of the final print product. If working in CMYK in a Euro color space, samples should be printed from Acrobat using a downloaded color sample PDF.
To match a color, look up the desired color in the sample book. Modify the color in the application to match the color value from the sample book, as illustrated in figure 6. The print results should match the color selected in the sample book. As CMYK is an over-defined color space, many values map to the same color; the values are described with K (black) equal to zero.
For more information
Go to: www.hp.com/support/lj4700
© 2005 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.
Adobe, Adobe PhotoShop, and PostScript are trademarks of Adobe Systems Incorporated. Microsoft and Windows are U.S. registered trademarks of Microsoft Corporation.