When using a Colors window in applications such as Keynote, Microsoft Word 2004, TextEdit, or others (for example, to change the color of text), you can optionally use Color Sliders to specify numerical values in Gray Scale, RGB, CMYK, or HSB colorspaces to achieve a desired color.
Usually, the values selected will change if a different color profile is selected in the color profile menu. (This menu is accessed by clicking the colored box icon just below the magnifying glass icon in the Colors window. The choices available in the color profile menu vary depending on which color slider choice is selected from the pop-up menu next to the colored box, such as "Gray Scale Sliders".)
The "Device RGB" color profile, visible in the color profile menu when the sliders pop-up menu is set to "RGB Sliders," represents the device that the color is being output to—typically a computer display. If color values are chosen in the "Generic RGB" profile for example, the values typically change when viewed in the "Device RGB" profile.
Why color values may appear to change
Since not all devices display color in the same way, a color profile defines how a particular device treats color, allowing Mac OS X and application programs to adjust color values to ensure the same actual color is output to all devices. The change in color values observed when switching color profiles is an indication that adjustments were necessary to preserve the perceived (actual) color value.
Note: When using the Magnifying Glass to select the color of a pixel on your screen, the "Device RGB" profile is used by default to determine the color values from the display.