Compiled from www.sketchpad.net and about.com
|Color Models: RGB vs. CMYK|
A color model is an orderly system for creating a whole
range of colors from a small set of primary colors. The two most common
color models are the RGB
model (Red-Green-Blue) for computer display and the
CMYK model (Cyan-Magenta-Yellow-blacK) for printing.
For you work to display at its best, choosing the right color model is critical.
The RGB model forms its gamut from the primary additive
colors of red, green and blue. When red, green and blue
light is combined it forms white. Computers generally
display RGB using 24-bit color. In the 24-bit RGB color
model there are 256 variations for each of the additive
colors of red, green and blue. Therefore there are 16,777,216
possible colors (256 reds x 256 greens x 256 blues)
in the 24-bit RGB color model.
CMYK or "Process Color"
The CMYK printing method is also known as "four-color process" or simply "process" color because in the CMYK color model colors are represented as percentages of cyan, magenta, yellow and black.
For example in the above CMYK chart the red color is composed of 14% cyan, 100% magenta, 99% yellow and 3% black. White would be 0% cyan, 0% magenta, 0% yellow and 0% black (a total absence of ink on white paper).
When In Doubt, Save Images As RGB
The RGB model displays a much larger percentage of the visible spectrum than the CMYK model. Once an image has been converted from RGB to CMYK, the extra RGB data will be lost.
Because of this fact, you want to scan or shoot images (with a digital camera) using the appropriate color model for their primary purpose. If the images will be used primarily for print then use CMYK. If they will be used primarily for screen displays, then use RGB. You can always convert from RGB to CMYK (or vise-versa) but it is best not to.
If you can afford the time, money and disk space to scan or shoot both versions of an image where both are needed, then this is the best solution. This is especially true if you will be using the same images for both printed material (such as a catalog) and the web (such as an online catalog). A little planning can go a long way here.
But if you are not sure, then I generally recommend saving images in RGB mode and creating CMYK copies for printed material as needed.
Bottom Line: Use RGB For Screen Displays and CMYK For Print
It is important to choose the right color model for the job. If your images will be printed, then convert them to CMYK. If your images are to be displayed on a computer, then make sure you use RGB color so the full gamut will be available for display. Because both models can be available at the same time while using an application, it is easy to make a mistake and choose the wrong palette or set of color swatches.
|How The Parts Fit Together|
The following chart shows how all the various parts fit together - vector vs. bitmap graphics, some of the various software applications used to create them (Adobe® Illustrator®, CorelDRAW®, Macromedia® FreeHand®, Adobe Photoshop®, Corel PHOTO-PAINT® and Paint Shop Pro), the four basic file formats and the two most common color models used in computer graphics for print media and the web: