Backup of Flash/SWF/spec/Bitmaps(No. 1)

Bitmaps

The SWF file format specification supports a variety of bitmap formats.
All bitmaps are compressed to reduce file size.
Lossy compression, best for imprecise images such as photographs, is provided by JPEG bitmaps; lossless compression, best for precise images such as diagrams, icons, or screen captures, is provided by ZLIB bitmaps.
Both types of bitmaps can optionally contain alpha channel (opacity) information.
The JPEG format, officially defined as ITU T.81 or ISO/IEC 10918-1, is an open standard developed by the Independent Joint Photographic Experts Group.
The JPEG format is not described in this document.
For general information on the JPEG format, see JPEG at www.jpeg.org/.
For a specification of the JPEG format, see the International Telecommunication Union at www.itu.int/ and search for recommendation T.81.
The JPEG data in SWF files is encoded using the JPEG Interchange Format specified in Annex B.
Flash Player also understands the popular JFIF format, an extension of the JPEG Interchange Format.
In all cases where arrays of non-JPEG pixel data are stored in bitmap tags, the pixels appear in row-major order, reading like English text, proceeding left to right within rows and top to bottom overall.