jpeg -
JPEG querying and manipulation of meta data
package require Tcl 8.2
package require jpeg ? 0.4.0 ?
::jpeg::isJPEG file
::jpeg::imageInfo file
::jpeg::dimensions file
::jpeg::getThumbnail file
::jpeg::getExif file ? section ?
::jpeg::getExifFromChannel channel ? section ?
::jpeg::formatExif keys
::jpeg::exifKeys
::jpeg::removeExif file
::jpeg::stripJPEG file
::jpeg::getComments file
::jpeg::addComment file text...
::jpeg::removeComments file
::jpeg::replaceComment file text
::jpeg::debug file
::jpeg::markers channel
This package provides commands to query and modify JPEG images. JPEG
stands for Joint Photography Experts Group and is a standard
for the lossy compression of photographical images. It is specified at
LINK_HERE.
-
::jpeg::isJPEG file
-
Returns a boolean value indicating if file is a
JPEG image.
-
::jpeg::imageInfo file
-
Returns a dictionary with keys version, units,
xdensity, ydensity, xthumb, and
ythumb. The values are the associated properties of the JPEG
image in file.
Throws an error if file is not a JPEG image.
-
::jpeg::dimensions file
-
Returns the dimensions of the JPEG file as a list of the
horizontal and vertical pixel count.
Throws an error if file is not a JPEG image.
-
::jpeg::getThumbnail file
-
This procedure will return the binary thumbnail image data, if a JPEG
thumbnail is included in file, and the empty string
otherwise. Note that it is possible to include thumbnails in formats
other than JPEG although that is not common. The command finds
thumbnails that are encoded in either the JFXX or EXIF segments of the
JPEG information. If both are present the EXIF thumbnail will take precedence.
Throws an error if file is not a JPEG image.
set fh [open thumbnail.jpg w+]
fconfigure $fh -translation binary -encoding binary
puts -nonewline $fh [::jpeg::getThumbnail photo.jpg]
close $fh
-
::jpeg::getExif file ? section ?
-
section must be one of main or thumbnail.
The default is main.
Returns a dictionary containing the EXIF information for the specified section.
For example:
set exif {
Make Canon
Model {Canon DIGITAL IXUS}
DateTime {2001:06:09 15:17:32}
}
Throws an error if file is not a JPEG image.
-
::jpeg::getExifFromChannel channel ? section ?
-
This command is as per ::jpeg::getExif except that it uses a
previously opened channel. channel should be a seekable channel
and section is as described in the documentation of
::jpeg::getExif
Note: the jpeg parser expects that the start of the channel is the
start of the image data. If working with an image embedded in a
container file format it may be necessary to read the jpeg data into
a temporary container: either a temporary file or a memory channel.
-
::jpeg::formatExif keys
-
Takes a list of key-value pairs as returned by getExif and formats
many of the values into a more human readable form. As few as one key-value
may be passed in, the entire exif is not required.
foreach {key val} [::jpeg::formatExif [::jpeg::getExif photo.jpg]] {
puts "$key: $val"
}
array set exif [::jpeg::getExif photo.jpg]
puts "max f-stop: [::jpeg::formatExif [list MaxAperture $exif(MaxAperture)]]
-
::jpeg::exifKeys
-
Returns a list of the EXIF keys which are currently understood.
There may be keys present in getExif data that are not understood.
Those keys will appear in a 4 digit hexadecimal format.
-
::jpeg::removeExif file
-
Removes the Exif data segment from the specified file and replaces
it with a standard JFIF segment.
Throws an error if file is not a JPEG image.
-
::jpeg::stripJPEG file
-
Removes all metadata from the JPEG file leaving only
the image. This includes comments, EXIF segments, JFXX
segments, and application specific segments.
Throws an error if file is not a JPEG image.
-
::jpeg::getComments file
-
Returns a list containing all the JPEG comments found in
the file.
Throws an error if file is not a valid JPEG image.
-
::jpeg::addComment file text...
-
Adds one or more plain text comments to the JPEG image
in file.
Throws an error if file is not a valid JPEG image.
-
::jpeg::removeComments file
-
Removes all comments from the file specified.
Throws an error if file is not a valid JPEG image.
-
::jpeg::replaceComment file text
-
Replaces the first comment in the file with the new text.
This is merely a shortcut for ::jpeg::removeComments
and ::jpeg::addComment
Throws an error if file is not a valid JPEG image.
-
::jpeg::debug file
-
Prints everything we know about the given file in a nice format.
-
::jpeg::markers channel
-
This is an internal helper command, we document it for use by advanced
users of the package. The argument channel is an open file
handle positioned at the start of the first marker (usually 2
bytes). The command returns a list with one element for each JFIF
marker found in the file. Each element consists of a list of the
marker name, its offset in the file, and its length. The offset points
to the beginning of the sections data, not the marker itself. The
length is the length of the data from the offset listed to the start
of the next marker.
can only work with files
cant write exif data
gps exif data not parsed
makernote data not yet implemented
This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category
jpeg of the
http://sourceforge.net/tracker/?group_id=12883.
Please also report any ideas for enhancements you may have for either
package and/or documentation.
jpeg, image, comment, exif, thumbnail, jfif