1JHEAD(1) General Commands Manual JHEAD(1)
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6 jhead - Digicam JPEG Exif header manipulation tool
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9 jhead [ options ] [ file... ]
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13 jhead is used to display and manipulate data contained in the Exif
14 header of JPEG images from digital cameras. By default, jhead displays
15 the more useful camera settings from the file in a user-friendly for‐
16 mat.
17 jhead can also be used to manipulate some aspects of the image relating
19 to JPEG and Exif headers, such as changing the internal timestamps,
20 removing the thumbnail, or transferring Exif headers back into edited
21 images after graphical editors deleted the Exif header. jhead can also
22 be used to launch other programs, similar in style to the UNIX find
23 command, but much simpler.
24
28 -te file
29 Transplant Exif header from a JPEG (with Exif header) in file
30 into the image that is manipulated. This option is useful if
31 you like to edit the photos but still want the Exif header on
32 your photos. As most photo editing programs will wipe out the
33 Exif header, this option can be used to re-copy them back from
34 original copies after editing the photos.
35 This feature has an interesting 'relative path' option for spec‐
38 ifying the thumbnail name. Whenever the <name> contains the
39 characters '&i', jhead will substitute the original filename
40 for this name. This allows creating a incantation:
41 jhead -te originalsi *.jpg
43 would transfer the exif header for each .jpg file in the origi‐
45 nals directory by the same name, Both Win32 and most Unix shells
46 treat the '&' character in a special way, so you have to put
47 quotes around that command line option for the
48 -dc Delete comment field from the JPEG header. Note that the com‐
51 ment is not part of the Exif header.
52 -de Delete the Exif header entirely. Leaves other metadata sections
54 intact.
55 -di Delete the IPTC section, if preent. Leaves other metadata sec‐
57 tions intact.
58 -dx Delete the XMP section, if preent. Leaves other metadata sec‐
60 tions intact.
61 -du Delete sections of jpeg that are not Exif, not comment, and oth‐
63 erwise not contributing to the image either - such as data that
64 photoshop might leave in the image.
65 -purejpg
67 Delete all JPEG sections that aren't necessary for rendering the
68 image. Strips any metadata that various applications may have
69 left in the image. A combintion of the -de -dc and -du options.
70 -mkexif
72 Creates minimal exif header. Exif header contains date/time, and
73 empty thumbnail fields only. Date/time set to file time by
74 default. use with -rgt option if you want the exif header to
75 contain a thumbnail. Note that exif header creation is very lim‐
76 ited at this time, and no other fields can be added to the exif
77 header this way.
78 -ce Edit the JPEG header comment field (note, this comment field is
80 outside the Exif structure and can be part of Exif and non Exif
81 style JPEG images).
82 A temporary file containing the comment is created and a text
84 editor is launched to edit the file. The editor is specified in
85 the EDITOR environment variable. if none is specified notpead
86 or vi are used under Windows and Unix respectively. After the
87 editor exits, the data is transferred back into the image, and
88 the temporary file deleted.
89 -cs file
91 Save comment section to a file
92 -ci file
94 Replace comment with text from file
95 -cl string
97 Replace comment with specified string from command line file
98
103 -ft Sets the file's system time stamp to what is stored in the Exif
104 header.
105 -dsft Sets the Exif timestamp to the file's timestamp. Requires an
107 Exif header to pre-exist. Use -mkexif option to create one if
108 needed.
109 -n[format_string]
111 This option causes files to be renamed using the date informa‐
112 tion from the Exif header "DateTimeOriginal" field. If the file
113 is not an Exif file, or the DateTimeOriginal does not contain a
114 valid value, the file date is used. Renaming is by default
115 restricted to files whose names consist largely of digits. This
116 effectively restricts renaming to files that have not already
117 been manually renamed, as the default sequential names from dig‐
118 ital cameras consist largely of digits. Use the -nf option to
119 force renaming of all files.
120 If the format_string is omitted, the file will be renamed to
122 MMDD-HHMMSS. Note that this scheme doesn't include the year (I
123 never have photos from different years together anyway).
124 If a format_string is provided, it will be passed to the strf‐
126 time function as the format string. In addition, if the format
127 string contains '%f', this will substitute the original name of
128 the file (minus extension). '%i' will substitute a sequence
129 number. Leading zeros can be specified like with printf - i.e.
130 '%04i' pads the number to 4 digits using leading zeros.
131 If the target name already exists, the name will be appended
133 with "a", "b", "c", etc, unless the name ends with a letter, in
134 which case it will be appended with "0", "1", "2", etc.
135 This feature is especially useful if more than one digital cam‐
137 era was used to take pictures of an event. By renaming them to
138 a scheme according to date, they will automatically appear in
139 order of taking in most directory listings and image browsers.
140 Alternatively, if your image browser supports listing by file
141 time, you can use the -ft option to set the file time to the
142 time the photo was taken.
143 Some of the more useful arguments for strftime are:
145 %H Hour in 24-hour format (00 - 23)
147 %j Day of year as decimal number (001 - 366)
148 %m Month as decimal number (01 - 12)
149 %M Minute as decimal number (00 - 59)
150 %S Second as decimal number (00 - 59)
151 %w Weekday as decimal number (0 - 6; Sunday is 0)
152 %y Year without century, as decimal number (00 - 99)
153 %Y Year with century, as decimal number
154 Example:
156 jhead -n%Y%m%d-%H%M%S *.jpg This will rename files matched by
158 *.jpg in the format YYYYMMDD-HHMMSS
159 For a full listing of strftime arguments, look up the strftime
161 in them man pages. Note that some arguments to the strftime
162 function (not listed here) produce strings with characters such
163 as '/' and ':' that may not be valid as part of a filename on
164 various systems.
165 -nf Same as '-n' but renames files regardless of original file name.
168 -ta<+|-><timediff>
172 Adjust time stored in the Exif header by h:mm backwards or for‐
173 wards. Useful when having taken pictures with the wrong time
174 set on the camera, such as after travelling across time zones,
175 or when daylight savings time has changed.
176 This option changes all Date/time fileds in the exif header,
178 including "DateTimeOriginal" (tag 0x9003) and "DateTimeDigi‐
179 tized" (tag 0x9004).
180 -da<newdate>-<olddate>
182 Works like -ta, but for specifying large date offsets, to be
184 used when fixing dates from cameras where the date was set
185 incorrectly, such as having date and time reset by battery
186 removal on some cameras
187 Because different months and years have different numbers of
189 days in them, a simple offset for months, days, years would lead
190 to unexpected results at times. The time offset is thus speci‐
191 fied as a difference between two dates, so that jhead can figure
192 out exactly how many days the timestamp needs to be adjusted by,
193 including leap years and daylight savings time changes. The
194 dates are specified as yyyy:mm:dd. For sub-day adjustments, a
195 time of day can also be included, by specifying yyyy:nn:dd/hh:mm
196 or yyyy:mm:dd/hh:mm:ss
197 Examples:
199 Year on camera was set to 2005 instead of 2004 for pictures
201 taken in April
202 jhead -da2005:03:01-2004:03:01
203 Default camera date is 2002:01:01, and date was reset on
205 2005:05:29 at 11:21 am
206 jhead -da2005:05:29+11:21-2002:01:01
207 -ts Sets the time stored in the Exif header to what is specified on
209 the command line. Time must be specified as: yyyy:mm:dd-
210 hh:mm:ss
211 -ds Sets the date stored in the Exif header to what is specified on
213 the command line. Can be used to set date, just year and month,
214 or just year. Date is specified as: yyyy:mm:dd, yyyy:mm, or
215 yyyy
216
220 -dt Delete thumbnails from the Exif header, but leave the interest‐
221 ing parts intact. This option truncates the thumbnail from the
222 Exif header, provided that the thumbnail is the last part of the
223 Exif header (which so far as I know is always the case). Exif
224 headers have a built-in thumbnail, which typically occupies
225 around 10k of space. This thumbnail is used by digital cameras.
226 Windows XP may also use this thumbnail if present (but it
227 doesn't need it). The thumbnails are too small to use even full
228 screen on the digicam's LCD. I have not encountered any adverse
229 side effects of deleting the thumbnails, even from the software
230 provided with my old Olympus digicam. Use with caution.
231 -st file
234 Save the integral thumbnail to file The thumbnail lives inside
235 the Exif header, and is a very low-res JPEG image. Note that
236 making any changes to a photo, except for with some programs,
237 generally wipes out the Exif header and with it the thumbnail.
238 The thumbnail is too low res to really use for very much.
240 This feature has an interesting 'relative path' option for spec‐
242 ifying the thumbnail name. Whenever the name for file contains
243 the characters '&i', jhead will substitute the original file‐
244 name for this name. This allows creating a 'relative name' when
245 doing a whole batch of files. For example, the incantation:
246 jhead -st thumbnails/&i *.jpg
248 would create a thumbnail for each .jpg file in the thumbnails
250 directory by the same name, (provided that the thumbnails direc‐
251 tory exists, of course). Both Win32 and UNIX shells treat the
252 '&'character in a special way, so you have to put quotes around
253 that command line option for the '&' to even be passed to the
254 program.
255 If a '-' is specified for the output file, the thumbnail is sent
257 to stdout. (UNIX build only)
258 -rt Replace thumbnails from the Exif header. This only works if the
261 exif header already contains a thumbnail, and the thumbnail is
262 at the end of the header (both always the case if the photo came
263 from a digital camera)
264 -rgt size
266 Regnerate exif thumbnail. Relies on 'mogrify' program (from
267 ImageMagick) to regenerate the thumbnail. This only works if
268 the image already contains a thumbail.
269
272 -autorot
273 Using the 'Orientation' tag of the Exif header, rotate the image
274 so that it is upright. The program jpegtran is used to perform
275 the rotation. This program is present in most Linux distribu‐
276 tions. For windows, you need to get a copy of it. After rota‐
277 tion, the orientation tag of the Exif header is set to '1' (nor‐
278 mal orientation). The thumbnail is also rotated. Other fields
279 of the Exif header, including dimensions are untouched, but the
280 JPEG height/width are adjusted. This feature is especially use‐
281 ful with newer Canon cameras, that set the orientation tag auto‐
282 matically using a gravity sensor.
283 -norot Clears the rotation field in the Exif header without altering
285 the image. Useful if the images were previously rotated without
286 clearing the Exif rotation tag, as some image browsers will auto
287 rotate images when the rotation tag is set. Sometimes, thun‐
288 bails and rotation tags can get very out of sync from manipula‐
289 tion with various tools. To reset it all use -norot with -rgt
290 to clear this out.
291
294 -h Displays summary of command line options.
295 -v Makes the program even more verbose than it already is. Like
297 DOS programs, and unlike UNIX programs, Jhead gives feedback as
298 to what it is doing, even when nothing goes wrong. Windows user
299 that I am, when something doesn't give me feedback for 20 sec‐
300 onds, I assume its crashed.
301 -q No output on success, more like Unix programs.
303 -V Print version info and compilation date. -exifmap Show a map of
305 the bytes in the exif header. Useful when analyzing strange exif
306 headers, not of much use to non software developers.
307 -se Suppress error messages relating to corrupt Exif header struc‐
309 ture.
310 -c Concise output. This causes picture info to be summarized on
312 one line instead of several. Useful for grep-ing through
313 images, as well as importing into spread sheets (data is space
314 delimited with quotes as text qualifier).
315
318 -model Restricts processing of files to those whose camera model, as
319 indicated by the Exif image information, contains the substring
320 specified in the argument after '-model'. For example, the fol‐
321 lowing command will list only images that are from an S100 cam‐
322 era:
323 jhead -model S100 *.jpg
325 jhead -model S100 *.jpg
327 I use this option to restrict my JPEG recompensing to those
329 images that came from my Cannon S100 digicam, (see the -cmd
330 option).
331 -exonly
333 Skip all files that don't have an Exif header. Photos straight
334 from a digital camera have an Exif header, whereas many photo
335 manipulation tools discard the Exif header.
336 -cmd Executes the specified command on each Jepg file to be pro‐
338 cessed.
339 The Exif section of each file is read before running the com‐
341 mand, and reinserted after the command finishes.
342 The specified command invoked separately for each JPEG that is
344 processed, even if multiple files are specified (explicitly or
345 by wild card). I use this option to process whole directory
346 trees of JPEGs from my digital camera with jpegtran (Independent
347 JPEG group) and ImageMagick's 'MOGRIFY' command without loosing
348 the camera settings and other info stored in the Exif headers.
349 jpegtran is useful for lossless rotation, as well as for con‐
351 verting JPEGs to progressive JPEGs (also a lossless process, but
352 results in typically 5% smaller files) I use mogrify for re-com‐
353 pressing the images I get from my Canon PowerShot S100 to 80%
354 quality. The Canon JPEGs are either way too 'high quality' for
355 the resolution, or are suboptimally encoded. Using mogrify to
356 80% produces no detectable loss in quality, with files about
357 half the size.
358 Example use:
360 Having a whole directory tree of photos from my S100, I run the
362 following commands:
363 jhead -cmd mogrify -quality 80 &i -model S100 -r *.jpg
365 jhead -cmd jpegtran -progressive &i > &o -r *.jpg
366 The first command mogrifies all JPEGs in the tree that indicate
368 that they are from a Cannon S100 in their Exif header to 80%
369 quality at the same resolution. This is a 'lossy' process, so I
370 only run it on files that are from the Canon, and only run it
371 once. The next command then takes a JPEGs and converts them to
372 progressive JPEGs. The result is the same images, with no dis‐
373 cernible differences, stored in half the space. This only pro‐
374 duces substantial savings on some cameras, such as the Canon
375 S100. The newer S110 and S300 cameras are smarter about how
376 they compress JPEG images, so re-mogrifying them may not give
377 you any savings unless you crank the quality way down. However,
378 turning them into progressive JPEG images is a lossless process
379 that typically makes image files 5% smaller.
380 Keeping the Exif header information is important to me, as I
382 like to check things like the shutter speed for some of my pho‐
383 tos, and my HTML index generating program uses the Exif tags to
384 display the JPEG images in order of taking.
385
388 jpegtran(1), mogrify(1), rdjpgcom(1), wrjpgcom(1)
389
391 Matthias Wandel
392
394 After jhead runs a program to rotate or resize an image, the image
395 dimensions and thumbnail in the Exif header are not adjusted.
396 Modifying of Exif header data is very limited, as Jhead internally only
398 has a read only implementation of the file system contained in the Exif
399 header. For example, there is no way to replace the thumbnail or edit
400 the Exif comment in the Exif header. There is also no way to create
401 minimal exif headers.
402 Some Canon digital SLR cameras fail to adjust the effective sensor res‐
404 olution when shooting at less than full resolution, causing jhead to
405 incorrectly miscalculate the sensor width and 35mm equivalent focal
406 length. The same can result from resizing photos with Photoshop, which
407 will manipulate parts of the exif header. This is often reported as a
408 bug in Jhead, but Jhead can't do much about incorrect data.
409 Send bug reports to mwandel at sentex dot net.
411
414 Jhead is 'public domain'. You may freely copy jhead, and reuse part or
415 all of its code in free or proprietary programs. I do however request
416 that you do not post my e-mail address in ways that spam robots can
417 harvest it.
418jhead 2.82 03 Apr 2008 JHEAD(1)