Inside Macintosh: QuickTime
The Image Compression Manager provides your application with an interface for compressing and decompressing images and sequences of images that is independent of devices and algorithms.
Uncompressed image data requires a large amount of storage space. Storing a single 640-by-480 pixel image in 32-bit color can require as much as 1.2 MB. Sequences of images, like those that might be contained in a QuickTime movie, demand substantially more storage than single images. This is true even for sequences that consist of fairly small images, because the movie consists of such a large number of those images. Consequently, minimizing the storage requirements for image data is an important consideration for any application that works with images or sequences of images.
The Image Compression Manager allows your application to
The Image Compression Manager compresses images by invoking image compressor components and decompresses images using image decompressor components. Compressor and decompressor components are code resources that present a standard interface to the Image Compression Manager and provide image-compression and image-decompression services, respectively. The Image Compression Manager receives application requests and coordinates the actions of the appropriate components. The components perform the actual compression and decompression. Compressor and decompressor components are standard components and are managed by the Component Manager. For detailed information about creating compressor and decompressor components, see Inside Macintosh: QuickTime Components .
Because the Image Compression Manager is independent of specific compression algorithms and drivers, it provides a number of advantages to developers of image- compression algorithms. Specifically, compressor and decompressor components can