Sign & Digital Graphics

October '14

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S I G N & D I G I T A L G R A P H I C S • October 2014 • 49 image capture device and the device's software calculates the voltage (strength) of each color. A number is assigned for each color so that each pixel contains three color values. The tonal information of the image is separated and stored as one of three color channels (see Figure 5). Each color channel is actually a gray- scale image that supports 256 levels. Once again, do the math. Eight on/off switches per pixel times three channels (256 3 ) equals 16,777,216, which is the potential number of colors in the eight- bit-per-pixel RGB gamut. Sometimes this is referred to as 24-bit color. That's the full potential of the monitor, the scanner and the camera. High-Bit images But wait! Some of you may ask, "What about high-bit images?" Of course, many scanners and some digital cameras can collect more color information than eight bits per pixel. Some images can contain 16 bits per pixel (48-bit color) that produce billions of colors or 32-bit HDR images which produce trillions of colors (and huge file sizes). Some photographers and digital art- ists swear that high-bit images produce better-quality images during the editing process because more colors produce smoother tonal variations. That might be true, however, the human eye can only distinguish about 10 million col- ors. Furthermore, the image will display at eight bits per pixel because that's the extent of your monitor's capabilities and the image will have to be converted to eight bits per pixel for printing. CMYK Color Mode The CMYK (cyan, magenta, yellow, and black) color mode produces a full range of color by printing tiny dots of cyan, magenta, yellow and black ink. Because the colored dots are so small, the eye mixes them together. The rela- tive densities of groups of colored dots produce variations in color and tonality (see Figure 6) The more ink you add to a CMYK image, the darker it becomes; conversely, less ink produces lighter colors, and the absence of ink produces white. For this reason, CMYK is referred to as a subtractive color system. You work in CMYK color mode to ultimately segre- gate colors into color separations for use in the offset lithography printing process. Although it has four color channels, the CMYK the gamut is limited to about 100,000 colors, so converting an RGB image to CMYK can change it's appear- ance. That is where color management comes into play and is the subject of another article—if not an entire book. You work in CMYK color mode to ultimately seg- regate colors into color separations for use in the offset lithography printing process. Simple, cost-effective and extremely easy to use, magnets give you the bag of tricks you need to provide effective solutions for graphics, sign and display building. Learn the secrets to profitable and creative sign and graphics design with magnets at Booth 3246

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