Notes on Exif Data Types

The Exif standard defines the following data types for comments. Usage is dependent of your development platform. To see the usage, refer to the code example for your platform.

Data type	Description
UNDEFINED	The data type is determined by the field.
SHORT	Integer
LONG	Long integer
ASCII	Character string
BYTE	Array of bytes
RATIONAL	An array of two unsigned long integers that express a fraction. The first value is the numerator, and the second is the denominator.
SRATIONAL	An array of two signed long integers that express a fraction. The first value is the numerator, and the second is the denominator.

The byte length of a comment is based on the data type. For example, an SRATIONAL with a length of 3 is an array of 6 long integers.

When a comment that requires an array is set, the array can be zero-based (where the first element has an index of 0) or one-based (where the first element has an index of 1). When you get a comment that is an array, it will always be zero-based.

Notes on Exif Data Types

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