C

caching levels: A Photoshop method for speeding screen redraws by storing commonly used elements for rapid access. You can set the number of levels you want to use on the Image Cache page of the Preferences box.

clipping paths: A method of exporting a file for use in a vector or layout application. The clipping path format masks out part of the image (for example, you can use this method to drop out the background in a product shot so that only the product object is visible).

CMYK color model: A color process using cyan, magenta, yellow, and black color variables. Used primarily in offset printing, CMYK color sports a smaller color range than its RGB counterpart. The conversion process between RGB and CYMK must be managed to ensure consistent and high-quality results.

CMYK image: A color image that uses the CMYK color model, featuring cyan, magenta, yellow, and black channels.

color model: A way of quantifying color. There are several color models in which you can identify a particular color; CMYK, RGB, HSB, Web, and Lab colors are all supported in Photoshop. In the RGB color model, for example, a particular color is identified as having a particular quantity of red, a particular amount of blue, and a particular amount of green. The range of available color varies between color models, so it is important to use a model that is suited to the specific image, as well as the overall Web or printing process being used.

Color Picker: A dialog box from which you can select the foreground or background color. The Color Picker displays a window with a range of color in a particular hue; move the Hue slider to see a different range of color. Click in the color window to select a color. The selected color is quantified in terms of Hue/Saturation/Brightness, Red/Green/Blue, Lab, CMYK, and hexadecimal (if you need to specify your colors to that degree).

color space: The range of unique colors that can be created for a given color model such as RGB or CMYK.

contact sheet: A Photoshop file that contains thumbnail references for all the images in a given folder. You can use contact sheets to send your client a list of images for approval, to archive, or just to help organize your graphics visually rather than with archaic filenames.