1jpeg(n) JPEG image manipulation jpeg(n)
2______________________________________________________________________________
6
8 jpeg - JPEG querying and manipulation of meta data
9
11 package require Tcl 8.2
12 package require jpeg ?0.5?
14 ::jpeg::isJPEG file
16 ::jpeg::imageInfo file
18 ::jpeg::dimensions file
20 ::jpeg::getThumbnail file
22 ::jpeg::getExif file ?section?
24 ::jpeg::getExifFromChannel channel ?section?
26 ::jpeg::formatExif keys
28 ::jpeg::exifKeys
30 ::jpeg::removeExif file
32 ::jpeg::stripJPEG file
34 ::jpeg::getComments file
36 ::jpeg::addComment file text...
38 ::jpeg::removeComments file
40 ::jpeg::replaceComment file text
42 ::jpeg::debug file
44 ::jpeg::markers channel
46______________________________________________________________________________
48
50 This package provides commands to query and modify JPEG images. JPEG
51 stands for Joint Photography Experts Group and is a standard for the
52 lossy compression of photographical images. It is specified at
53 LINK_HERE.
54
56 ::jpeg::isJPEG file
57 Returns a boolean value indicating if file is a JPEG image.
58 ::jpeg::imageInfo file
60 Returns a dictionary with keys version, units, xdensity, yden‐
61 sity, xthumb, and ythumb. The values are the associated proper‐
62 ties of the JPEG image in file. Throws an error if file is not
63 a JPEG image.
64 ::jpeg::dimensions file
66 Returns the dimensions of the JPEG file as a list of the hori‐
67 zontal and vertical pixel count. Throws an error if file is not
68 a JPEG image.
69 ::jpeg::getThumbnail file
71 This procedure will return the binary thumbnail image data, if a
72 JPEG thumbnail is included in file, and the empty string other‐
73 wise. Note that it is possible to include thumbnails in formats
74 other than JPEG although that is not common. The command finds
75 thumbnails that are encoded in either the JFXX or EXIF segments
76 of the JPEG information. If both are present the EXIF thumbnail
77 will take precedence. Throws an error if file is not a JPEG im‐
78 age.
79 set fh [open thumbnail.jpg w+]
82 fconfigure $fh -translation binary -encoding binary
83 puts -nonewline $fh [::jpeg::getThumbnail photo.jpg]
84 close $fh
85 ::jpeg::getExif file ?section?
88 section must be one of main or thumbnail. The default is main.
89 Returns a dictionary containing the EXIF information for the
90 specified section. For example:
91 set exif {
95 Make Canon
96 Model {Canon DIGITAL IXUS}
97 DateTime {2001:06:09 15:17:32}
98 }
99 Throws an error if file is not a JPEG image.
102 ::jpeg::getExifFromChannel channel ?section?
104 This command is as per ::jpeg::getExif except that it uses a
105 previously opened channel. channel should be a seekable channel
106 and section is as described in the documentation of ::jpeg::ge‐
107 tExif.
108 Note: The jpeg parser expects that the start of the channel is
110 the start of the image data. If working with an image embedded
111 in a container file format it may be necessary to read the jpeg
112 data into a temporary container: either a temporary file or a
113 memory channel.
114 Attention: It is the resonsibility of the caller to close the
116 channel after its use.
117 ::jpeg::formatExif keys
119 Takes a list of key-value pairs as returned by getExif and for‐
120 mats many of the values into a more human readable form. As few
121 as one key-value may be passed in, the entire exif is not re‐
122 quired.
123 foreach {key val} [::jpeg::formatExif [::jpeg::getExif photo.jpg]] {
126 puts "$key: $val"
127 }
128 array set exif [::jpeg::getExif photo.jpg]
133 puts "max f-stop: [::jpeg::formatExif [list MaxAperture $exif(MaxAperture)]]
134 ::jpeg::exifKeys
137 Returns a list of the EXIF keys which are currently understood.
138 There may be keys present in getExif data that are not under‐
139 stood. Those keys will appear in a 4 digit hexadecimal format.
140 ::jpeg::removeExif file
142 Removes the Exif data segment from the specified file and re‐
143 places it with a standard JFIF segment. Throws an error if file
144 is not a JPEG image.
145 ::jpeg::stripJPEG file
147 Removes all metadata from the JPEG file leaving only the image.
148 This includes comments, EXIF segments, JFXX segments, and appli‐
149 cation specific segments. Throws an error if file is not a JPEG
150 image.
151 ::jpeg::getComments file
153 Returns a list containing all the JPEG comments found in the
154 file. Throws an error if file is not a valid JPEG image.
155 ::jpeg::addComment file text...
157 Adds one or more plain text comments to the JPEG image in file.
158 Throws an error if file is not a valid JPEG image.
159 ::jpeg::removeComments file
161 Removes all comments from the file specified. Throws an error
162 if file is not a valid JPEG image.
163 ::jpeg::replaceComment file text
165 Replaces the first comment in the file with the new text. This
166 is merely a shortcut for ::jpeg::removeComments and ::jpeg::add‐
167 Comment Throws an error if file is not a valid JPEG image.
168 ::jpeg::debug file
170 Prints everything we know about the given file in a nice format.
171 ::jpeg::markers channel
173 This is an internal helper command, we document it for use by
174 advanced users of the package. The argument channel is an open
175 file handle positioned at the start of the first marker (usually
176 2 bytes). The command returns a list with one element for each
177 JFIF marker found in the file. Each element consists of a list
178 of the marker name, its offset in the file, and its length. The
179 offset points to the beginning of the sections data, not the
180 marker itself. The length is the length of the data from the
181 offset listed to the start of the next marker.
182
184 can only work with files cant write exif data gps exif data not parsed
185 makernote data not yet implemented
186
188 This document, and the package it describes, will undoubtedly contain
189 bugs and other problems. Please report such in the category jpeg of
190 the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
191 also report any ideas for enhancements you may have for either package
192 and/or documentation.
193 When proposing code changes, please provide unified diffs, i.e the out‐
195 put of diff -u.
196 Note further that attachments are strongly preferred over inlined
198 patches. Attachments can be made by going to the Edit form of the
199 ticket immediately after its creation, and then using the left-most
200 button in the secondary navigation bar.
201
203 comment, exif, image, jfif, jpeg, thumbnail
204
206 File formats
207
209 Copyright (c) 2004-2005, Code: Aaron Faupell <afaupell@users.sourceforge.net>
210 Copyright (c) 2007, Code: Andreas Kupries <andreas_kupries@users.sourceforge.net>
211 Copyright (c) 2004-2009, Doc: Andreas Kupries <andreas_kupries@users.sourceforge.net>
212 Copyright (c) 2011, Code: Pat Thoyts <patthoyts@users.sourceforge.net>
213tcllib 0.5 jpeg(n)