Q+A CENTER

Feature

The JAI Top 10: Sun Engineers Answer Tough Questions about Java Advanced Imaging API

by Brian Burkhalter

October 2002

Brian Burkhalter, JAI.
There's one constant in technology: it's always changing. The Java Advanced Imaging (JAI) API is no exception. We receive many inquiries about this optional Java package for advanced image processing applications. This Q&A provides responses to some of the most frequently asked questions and briefly introduces JAI . To download JAI, you can join the JAI Interest Group. To find out more about JAI, please refer to the JAI home page at http://java.sun.com/products/java-media/jai/index.html. The current version of JAI is 1.1.1_01 with version 1.1.2 scheduled for release later in 2002.

1. How can I perform an image processing operation using JAI?
If the operation is one of the more than 100 operations provided intrinsically by JAI, it will correspond to a class in the package javax.media.jai.operator and implement the javax.media.jai.OperationDescriptor interface. By convention, the name of each operation matches the prefix of its OperationDescriptor class, so for operation "Warp" this would be "WarpOperationDescriptor." The HTML documentation or "javadoc" of these OperationDescriptors provides a textual description of the operation as well as the name, class, and default value of each parameter. The simplest way to instantiate a rendered JAI operation is to use the create(operationName,ParameterBlock,RenderingHints) method of the class javax.media.jai.JAI. The arguments of this method provide the name, sources, and parameters of the operation, as well as "hints" regarding desired image layout, tile caching, etc.

2. What if JAI does not include an operation I need?
All operations in JAI are plug-ins. This permits developers to extend the API by defining new operations and their implementations. Each operation may have multiple, priority-ordered implementations. This allows for special case implementations with assigned higher priority to attempt to handle processing for a given operation with fallback to a general purpose implementation. This is, in fact, what JAI itself does with its own native acceleration programmed for the OS and CPU, which falls back to the Java implementation for cases which cannot be handled by the native implementation. All intrinsic JAI operations have complete Java versions.\