The EXIF documentation file: The EXIF Package

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The EXIF documentation file | D. New
| February 12, 2002

The EXIF Package

### Abstract

Tcl EXIF extracts and parses EXIF fields from digital images.

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### Table of Contents

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### 1. Synopsis

        package provide exif 1.0

The EXIF package is a recoding of Chris Breeze's Perl package to do the same thing. This version accepts a channel as input and returns a serialized array with all the recognised fields parsed out.

There is also a function to obtain a list of all possible field names that might be present, which is useful in building GUIs that present such information.

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### 2. Details

        array set answer [exif::analyze $channel]

$channel should be an open file handle rewound to the start. It does not need to be seekable. $channel will be set to binary mode and is left wherever it happens to stop being parsed, usually at the end of the file or the start of the image data. You must open and close the stream yourself. If no error is thrown, the return value is a serialized array with informative English text about what was found in the EXIF block. Failure during parsing or I/O throw errors.

        set names [exif::fieldnames]

This returns a list of all possible field names. That is, the array returned by exif::analyze will not contain keys that are not listed in the return from exif::fieldnames. Of course, if information is missing in the image file, exif::analyze may not return all the fields listed in the return from exif::fieldnames. This function is expected to be primarily useful for building GUIs to display results. N.B.: Read the implementation of exif::fieldnames before modifying the implementation of exif::analyze.

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### 3. Copyrights

(c) 2002 Darren New

Hold harmless the author, and any lawful use is allowed.

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### 4. Acknowledgements

This code is a direct translation of version 1.3 of exif.pl by Chris Breeze. See the source for full headers, references, etc.