JEITA CP-3451
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4 Exif Image File Specification
4.1 Outline of the Exif Image File Specification
This chapter gives details of the image file specification, covering the following items:
· Format version definition,
· Specifications relating to image data,
· Basic structure of image data,
· Tags,
· JPEG marker segments,
· Specifications on data recording.
4.2 Format Version
The version of the format specified here is recorded as 4 bytes (see section 4.6.5). The address bytes are recorded
as A1, A2, B1, and B2, starting with the lowest number. A1 and A2 store the upper part of the standard version,
with the lower part stored in B1 and B2. When changes are made to the version number of this standard, the
following rules apply.
· When the changes are such that data readers can properly recognize conventional information and skip the
data that was recorded using newly added functions, the lower part of the version (B1, B2) is changed.
· When there is a possibility that a data reader implementing the old standard may operate incorrectly due to the
new specifications, the upper part of the version (A1, A2) is changed.
Players should be able to play back files of versions earlier than the supported standard.
4.3 Definition of Glossary
Terms and notation are used as follows in this standard:
· "Tag" is used as a synonym of "field",
· ".H" appended to a numerical value means it is hexadecimal notation,
· Unless otherwise indicated, other numerical values are given in decimal notation,
· The initial IFD in a file is the "0th IFD," with the next IFD being called the 1st IFD,