Inside Macintosh: Advanced Color Imaging on the Mac OS /

Chapter 4 - Developing ColorSync-Supportive Applications

This chapter describes how you can use the ColorSync Manager to provide your users with color-matching and color gamut-checking services. Your ColorSync-supportive application can match the colors of an image created using one device to the color gamut of another device on which the image is to be rendered. Your application can allow your users to preview the results and adjust the colors of the matched image if desirable. To match or check the colors of an image across devices with different gamuts and characteristics, the ColorSync Manager uses profiles that contain information depicting a device. Using the ColorSync Manager, your application can search for and display a list or menu containing the names of available profiles for a particular device type, such as a printer, and allow your users to select the profile to define the destination device. You can modify the content of profiles to change how an image is rendered. These and other features that your application can provide using the ColorSync Manager are described in this chapter.

Note

See the preface for information on ColorSync Manager version numbers.

You need to read this chapter if your application will support the ColorSync Manager and provide your users with various color-matching and color-checking features. You should read this chapter even if you will provide only minimal support allowing your users to modify documents containing color images created using other applications that fully support the ColorSync Manager. This chapter tells you how to preserve profiles embedded in documents along with the images with which they are associated.

The features described in this chapter can also be used in developing ColorSync-supportive device drivers. Therefore, if you are developing a device driver that supports the ColorSync Manager, you should read this chapter in addition to "Developing ColorSync-Supportive Device Drivers" (page 6-3).

Before you read this chapter, you should read "Introduction to the ColorSync Manager" (page 3-3), which explains color theory and color management systems (CMSs). It provides an overview of the ColorSync Manager CMS, including the use of profiles, and also explains key terms.

While reading this chapter, you might want to refer to "ColorSync Manager Reference for Applications and Device Drivers" in Advanced Color Imaging Reference for details related to functions this chapter discusses.

Most high-level applications that support the ColorSync Manager automatically use either the color management module (CMM) specified by the source profile or the Apple-supplied default CMM, as determined internally by the CMM selection algorithm described later in this chapter. For this reason, you do not need to read the two ColorSync Manager chapters addressed to developers who provide CMMs--"Developing Color Management Modules" (page 5-3) in this book and "ColorSync Manager Reference for Color Management Modules" (page 4-3) in Advanced Color Imaging Reference. Nor do you need to read "Developing ColorSync-Supportive Device Drivers" (page 6-3) in this book. However, you should read the appendix, "ColorSync Manager Backward Compatibility."

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Chapter Contents

About ColorSync Application Development

About the ColorSync Manager Programming Interface

What Should a ColorSync-Supportive Application Do?

At a Minimum

Storing and Handling Profiles

How the ColorSync Manager Selects a CMM

Developing Your ColorSync-Supportive Application

Determining if the ColorSync Manager Is Available

Providing Minimal ColorSync Support

Obtaining Profile References

Opening a Profile and Obtaining a Reference to It

Identifying the Current Default System Profile

Matching Colors to Displays Using ColorSync With QuickDraw Operations

Matching Colors in a Picture Containing an Embedded Profile or Profile Identifier

Considerations

Matching Colors as Your User Draws a Picture

Creating a Color World for Color Matching and Checking Using the Low-Level Functions

Matching Colors Using the Low-Level Functions

Matching the Colors of a Pixel Map to the Display's Color Gamut

Matching the Colors of a Bitmap Image to the Display's Color Gamut

Embedding Profiles and Profile Identifiers

Embedded Profile Format

Embedding Different Profile Versions

The NCMUseProfileComment Function

Extracting Profiles Embedded in Pictures

Step 1: Count the Profiles in the PICT File

Step 2: Extract the Profile

Part A: Calling the Unflatten Function

Part B: Calling the Unflatten Function

Part C: Calling the Comment Procedure

Searching for Profiles in the ColorSync(TM) Profiles Folder

Checking Colors Against a Destination Device's Gamut

Creating and Using Device-Linked Profiles

Considerations

Providing Soft Proofs

Calibrating a Device

Accessing a Resource-Based Profile With a Procedure

Defining a Data Structure for a Resource-Based Profile

Setting Up a Location Structure for Procedure Access to a Resource-Based Profile

Disposing of a Resource-Based Profile Access Structure

Responding to a Procedure-Based Profile Command

Handling the Begin Access Command

Handling the Create New Access Command

Handling the Open Read Access Command

Handling the Open Write Access Command

Handling the Read Access Command

Handling the Write Access Command

Handling the Close Access Command

Handling the Abort Write Access Command

Handling the End Access Command

Searching for a Profile That Matches a Profile Identifier

Summary of the ColorSync Manager

Constants

Data Structures

Functions

Accessing Profile Files

Accessing Profile Elements

Accessing Named Color Profile Values

Matching Colors Using High-Level Functions With QuickDraw

Matching Colors Using Low-Level Functions Without QuickDraw

Using Embedded Profiles With QuickDraw

Assigning and Accessing the System Profile File

Searching External Profiles

Searching For a Profile by Profile Identifier

Converting Between Color Spaces

PostScript Color-Matching Support Functions

Locating the ColorSync(TM) Profiles Folder

Converting 2.x Profiles to 1.0 Format

Obtaining Information About a Color World

Application-Supplied Functions for the ColorSync Manager