JEITA CP-3451
- 2 -
3.2 Exif Image File Specification
The Exif image file specification stipulates the method of recording image data in files, and specifies the following
items:
· Structure of image data files,
· Tags used by this standard,
· Definition and management of format versions.
Features of the Exif image file specification include the following.
The file-recording format is based on existing formats. Compressed files are recorded as JPEG (ISO/IEC 10918-1)
with application marker segments (APP1 and APP2) inserted. Uncompressed files are recorded in TIFF Rev. 6.0
format. The use of existing formats means files recorded using a DSC or related system can be read directly by
commercial applications, and makes possible the use of functions for viewing and manipulating the images.
Related attribute information for both compressed and uncompressed files is stored in the tag information format
defined in TIFF Rev. 6.0. Information specific to the camera system and not defined in TIFF is stored in private tags
registered for Exif. The Exif image file specification also specifies the method for recording thumbnails. The reason
for using the TIFF Rev. 6.0 tag format in the compressed file APP1 segment is to facilitate exchange of attribute
data between Exif compressed and uncompressed files.
Compressed files can record extended data exceeding 64 Kbytes by dividing it into multiple APP2 segments. The
APP2 segment is used when recording Flashpix extensions.
Details of the Exif image file specification are given in Chapter 4 of this document.
3.3 Exif Audio File Specification
The Exif audio file specification stipulates the method of writing audio data in files, and specifies the following items:
· Structure of audio data files,
· Chunks,
· Definition and management of format versions.
Features of the Exif audio file specification include the following.
Files are recorded using the existing RIFF WAVE Form Audio File format. As data formats, PCM and m-Law PCM
(conforming to ITU-T G.711) are used for uncompressed audio data, and IMA-ADPCM for compressed audio data.
As with the image files specification, the aim is to enable direct reading, playback and manipulation of the files
using the functions in commercial applications.
Related attribute information is stored as an INFO list in the case of general attributes, and as Exif-specific chunks
in the case of attributes specific to Exif. The Exif-specific chunks are newly provided to enable necessary
information to be added by making use of chunk extensibility. The recording of data in an Exif-specific chunk is
done in the same way as for an INFO list.
Details of the Exif audio file specification are given in Chapter 5 of this document.