Colors must often be converted when they are displayed on a monitor or sent to a printer. Conversion is necessary when the color models do not match (for example, when CMYK color is displayed on an RGB monitor, or when a document with images in an RGB color space is sent to a printer).
Acrobat uses the source color spaces of objects in a PDF to determine what (if any) color conversion is required, for example, from RGB to CMYK. If a PDF contains objects with embedded color profiles, Acrobat manages the colors using the embedded profiles rather than the default color spaces. For images and other objects in the PDF that contain embedded color profiles, Acrobat uses the information in the profile to determine how to handle the appearance of the color. For objects with managed colors (those with embedded color profiles), this conversion is well understood. Unmanaged colors, however, do not use profiles, so one must be temporarily used for the purpose of conversion. The Color Management panel of the Preferences dialog box provides profiles for converting unmanaged colors. You can also select specific profiles based on local press conditions.