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Inside Macintosh: Advanced Color Imaging on the Mac OS /

Chapter 4 - Developing ColorSync-Supportive Applications / About ColorSync Application Development

What Should a ColorSync-Supportive Application Do?

Your ColorSync-supportive application can provide a rich set of color-matching features. Your application can color match images, pixel maps, bitmaps, and even individual colors. In addition to color matching, you can handle such tasks as color conversion, color gamut checking, soft proofing of images, profile management, profile searching and accessing, reading individual tagged elements within a profile, embedding profiles in documents, extracting embedded profiles, and modifying profiles.

Your application's interface can offer selection menus allowing the user to choose which profile to associate with an image and how an image is rendered. It can show the user the colors of an image that are in or out of gamut for a particular device on which the image is to be produced and how the ColorSync Manager adjusts for colors that are out of gamut. This allows the user to preview differences that occur in the color-matching transition between gamuts and make corrections if necessary.

At a Minimum

The ColorSync Manager allows your application to preserve high fidelity to the original colors of an image--whether the image was created using your application or another--by supporting the use of embedded profiles. Your application can take advantage of a profile embedded along with an image, matching the original colors of the device used to create the image to those of the destination display or printer. Even if your application doesn't support some of the more advanced features the ColorSync Manager affords, such as soft proofing, you should color match images using the source profile, if one is identified and available.

At a minimum, your application should preserve images tagged with a profile by not stripping out picture comments used to embed profiles or by leaving profiles in documents that use other methods to include them.

It is important for your application to tag an image with the profile for the device used to create the image and to preserve existing tagging because a picture that is not tagged assumes use of the system profile. If the picture is moved to a different system that uses a different system profile, the picture will be drawn differently. "Providing Minimal ColorSync Support" (page 4-15) explains how to preserve embedded profiles, and "Embedding Profiles and Profile Identifiers" (page 4-32) explains how to tag an image. Some of these features are described in greater detail in the rest of this chapter.

Storing and Handling Profiles

Profiles for use with the ColorSync Manager are stored in the ColorSync(TM) Profiles folder within the Preferences folder of the System Folder. When you install the ColorSync Manager, the ColorSync(TM) Profiles folder contains a selection of display profiles for all Apple color monitors.

The ColorSync Manager provides a control panel, the ColorSync System Profile control panel, to allow the user to select the profile corresponding to the system's display. This profile then becomes the system profile. Your application specifies the profiles for color matching when the application calls a ColorSync Manager function. For most functions, the ColorSync Manager uses the system profile as the default profile if your application doesn't specify a profile. Some functions require that you explicitly specify a profile by reference.

Device drivers for ColorSync-supportive input and output devices, such as scanners and printers, may install the profiles they use in the ColorSync(TM) Profiles folder, making them available to your application for color matching or gamut checking. If your application creates device-linked profiles, as described in "Creating and Using Device-Linked Profiles" (page 4-52), you should place them in the ColorSync(TM) Profiles folder.

Your application can provide the interface to allow your user to choose a profile for a specific device. Using the ColorSync Manager functions, your application can search the ColorSync(TM) Profiles folder and display information about available profiles to your user.

These features are described in greater detail in the rest of this chapter. As described in "Providing Minimal ColorSync Support" (page 4-15), your application should, at a minimum, leave profile information intact in the documents and pictures that it imports or copies into its own documents.