Provided by: jhead_3.04-1ubuntu0.2_amd64 bug

NAME

       jhead - Digicam JPEG Exif header manipulation tool

SYNOPSIS

       jhead [ options ] [ file...  ]

DESCRIPTION

       jhead  is  used  to  display and manipulate data contained in the Exif header of JPEG images from digital
       cameras.  By default, jhead displays the more useful camera settings from the  file  in  a  user-friendly
       format.

       jhead can also be used to manipulate some aspects of the image relating to JPEG and Exif headers, such as
       changing the internal timestamps, removing the thumbnail, or transferring Exif headers back  into  edited
       images after graphical editors deleted the Exif header.  jhead can also be used to launch other programs,
       similar in style to the UNIX find command, but much simpler.

GENERAL METADATA OPTIONS

       -te file
              Transplant Exif header from a JPEG (with Exif header) in file into the image that is  manipulated.
              This  option  is  useful  if  you  like  to edit the photos but still want the Exif header on your
              photos.  As most photo editing programs will wipe out the Exif header, this option can be used  to
              re-copy them back from original copies after editing the photos.

              This  feature  has  an  interesting  'relative  path'  option  for  specifying the thumbnail name.
              Whenever the <name> contains the characters '&i', will substitute the original  filename for  this
              name.  This  allows  creating  a  jhead  'relative  name'  when doing a whole batch  of files. For
              example, the incantation:

              jhead -te "originals/&i" *.jpg

              would transfer the exif header for each .jpg file in the originals directory  by  the  same  name,
              Both  Win32  and  most  Unix  shells  treat the '&' character in a special way, so you have to put
              quotes around that command line option for the '&' to even be passed to the program.

       -dc    Delete comment field from the JPEG header.  Note that the comment is not part of the Exif header.

       -de    Delete the Exif header entirely.  Leaves other metadata sections intact.

       -di    Delete the IPTC section, if present.  Leaves other metadata sections intact.

       -dx    Delete the XMP section, if present.  Leaves other metadata sections intact.

       -du    Delete sections of jpeg that are not Exif, not comment, and  otherwise  not  contributing  to  the
              image either - such as data that photoshop might leave in the image.

       -purejpg
              Delete  all JPEG sections that aren't necessary for rendering the image.  Strips any metadata that
              various applications may have left in the image.  A combination of the -de -dc and -du options.

       -mkexif
              Creates minimal exif header. Exif header contains date/time,  and  empty  thumbnail  fields  only.
              Date/time set to file time by default. Use with -rgt option if you want the exif header to contain
              a thumbnail. Note that exif header creation is very limited at this time, and no other fields  can
              be added to the exif header this way.

       -ce    Edit the JPEG header comment field (note, this comment field is outside the Exif structure and can
              be part of Exif and non Exif style JPEG images).

              A temporary file containing the comment is created and a text editor is launched to edit the file.
              The  editor  is  specified in the EDITOR environment variable.  If none is specified notepad or vi
              are used under Windows and Unix respectively.  After the editor exits,  the  data  is  transferred
              back into the image, and the temporary file deleted.

       -cs file
              Save comment section to a file

       -ci file
              Replace comment with text from file

       -cl string
              Replace comment with specified string from command line

DATE / TIME MANIPULATION OPTIONS

       -ft    Sets the file's system time stamp to what is stored in the Exif header.

       -dsft  Sets the Exif timestamp to the file's timestamp. Requires an Exif header to pre-exist. Use -mkexif
              option to create one if needed.

       -n[format_string]
              This option causes files to be renamed and/ or mmoved using the date  information  from  the  Exif
              header  "DateTimeOriginal"  field.   If the file is not an Exif file, or the DateTimeOriginal does
              not contain a valid value, the file date is used.  If the new name contains a '/',  this  will  be
              interpreted as a new path, and the file will be moved accordingly.

              If  the  format_string is omitted, the file will be renamed to MMDD-HHMMSS.  Note that this scheme
              doesn't include the year (I never have photos from different years together anyway).

              If a format_string is provided, it will be passed to the strftime function as the  format  string.
              In  addition,  if  the  format string contains '%f', this will substitute the original name of the
              file (minus extension).  '%i' will substitute a sequence number.  Leading zeros can  be  specified
              like with printf - i.e. '%04i' pads the number to 4 digits using leading zeros.

              If  the  name  includes '/', this is interpreted as a new path for the file.  If the new path does
              not exist, the path will be created.

              If the target name already exists, the name will be appended with "a", "b", "c", etc,  unless  the
              name ends with a letter, in which case it will be appended with "0", "1", "2", etc.

              This  feature is especially useful if more than one digital camera was used to take pictures of an
              event.  By renaming them to a scheme according to date, they will automatically appear in order of
              taking  in  most  directory  listings  and  image  browsers.  Alternatively, if your image browser
              supports listing by file time, you can use the -ft option to set the file time  to  the  time  the
              photo was taken.

              Some of the more useful arguments for strftime are:

              %H Hour in 24-hour format (00 - 23)
              %j Day of year as decimal number (001 - 366)
              %m Month as decimal number (01 - 12)
              %M Minute as decimal number (00 - 59)
              %S Second as decimal number (00 - 59)
              %w Weekday as decimal number (0 - 6; Sunday is 0)
              %y Year without century, as decimal number (00 - 99)
              %Y Year with century, as decimal number

              Example:

              jhead -n%Y%m%d-%H%M%S *.jpg

              This will rename files matched by *.jpg in the format YYYYMMDD-HHMMSS

              For  a full listing of strftime arguments, look up the strftime in them man pages.  Note that some
              arguments to the strftime function (not listed here) produce strings with characters such  as  ':'
              that may not be valid as part of a filename on some systems.

       -ta<+|-><timediff>
              Adjust  time  stored  in  the Exif header by h:mm forwards or backwards.  Useful when having taken
              pictures with the wrong time set on the camera, such as after travelling  across  time  zones,  or
              when daylight savings time has changed.

              Examples:

              Add 1 hourand 5 minutes to the time
              jhead -ta+1:05

              Decrease time by one second:
              jhead -ta-0:0:1

              This  option  changes  all  Date/time fields in the exif header, including "DateTimeOriginal" (tag
              0x9003) and "DateTimeDigitized" (tag 0x9004).

       -da<newdate>-<olddate>

              Works like -ta, but for specifying large date offsets, to be used when fixing dates  from  cameras
              where  the date was set incorrectly, such as having date and time reset by battery removal on some
              cameras

              Because different months and years have different numbers of days in them,  a  simple  offset  for
              months,  days, years would lead to unexpected results at times.  The time offset is thus specified
              as a difference between two dates, so that  jhead  can  figure  out  exactly  how  many  days  the
              timestamp  needs  to  be adjusted by, including leap years and daylight savings time changes.  The
              dates are specified as yyyy:mm:dd.  For sub-day adjustments, a time of day can also  be  included,
              by specifying yyyy:nn:dd/hh:mm or yyyy:mm:dd/hh:mm:ss

              Examples:

              Year on camera was set to 2005 instead of 2004 for pictures taken in April
              jhead -da2004:03:01-2005:03:01

              Default camera date is 2002:01:01, and date was reset on 2005:05:29 at 11:21 am
              jhead -da2005:05:29/11:21-2002:01:01

       -ts    Sets  the  time  stored in the Exif header to what is specified on the command line.  Time must be
              specified as: yyyy:mm:dd-hh:mm:ss

       -ds    Sets the date stored in the Exif header to what is specified on the command line.  Can be used  to
              set date, just year and month, or just year.  Date is specified as: yyyy:mm:dd, yyyy:mm, or yyyy

THUMBNAIL MANIPULATION OPTIONS

       -dt    Delete  thumbnails  from  the  Exif  header,  but leave the interesting parts intact.  This option
              truncates the thumbnail from the Exif header, provided that the thumbnail is the last part of  the
              Exif  header (which so far as I know is always the case).  Exif headers have a built-in thumbnail,
              which typically occupies around 10k of space.  This thumbnail is used by digital cameras.  Windows
              XP  may also use this thumbnail if present (but it doesn't need it).  The thumbnails are too small
              to use even full screen on the digicam's LCD.  I have not encountered any adverse side effects  of
              deleting  the  thumbnails,  even from the software provided with my old Olympus digicam.  Use with
              caution.

       -st file
              Save the integral thumbnail to file The thumbnail lives inside the Exif header, and is a very low-
              res JPEG image.  Note that making any changes to a photo, except for with some programs, generally
              wipes out the Exif header and with it the thumbnail.

              The thumbnail is too low res to really use for very much.

              This feature has an  interesting  'relative  path'  option  for  specifying  the  thumbnail  name.
              Whenever  the  name  for  file  contains  the characters  '&i', jhead will substitute the original
              filename for this name.  This allows creating a 'relative name' when doing a whole batch of files.
              For example, the incantation:

              jhead -st "thumbnails/&i" *.jpg

              would  create  a  thumbnail  for  each  .jpg  file  in  the thumbnails directory by the same name,
              (provided that the thumbnails directory exists, of course).  Both Win32 and UNIX shells treat  the
              '&'character  in  a special way, so you have to put quotes around that command line option for the
              '&' to even be passed to the program.

              If a '-' is specified for the output file, the thumbnail is sent to stdout. (UNIX build only)

       -rt    Replace thumbnails from the Exif header.  This only works if the exif header  already  contains  a
              thumbnail,  and  the thumbnail is at the end of the header (both always the case if the photo came
              from a digital camera)

       -rgt size
              Regenerate exif thumbnail.  'size' specifies maximum height or  width  of  thumbnail.   Relies  on
              'mogrify'  program  (from  ImageMagick) to regenerate the thumbnail.  This only works if the image
              already contains a thumbnail.

ROTATION OPTIONS

       -autorot
              Using the 'Orientation' tag of the Exif header, rotate the image  so  that  it  is  upright.   The
              program  jpegtran  is  used  to  perform  the  rotation.  This  program  is  present in most Linux
              distributions.  For windows, you need to get a copy of it.  After rotation, the orientation tag of
              the  Exif  header is set to '1' (normal orientation).  The thumbnail is also rotated. Other fields
              of the Exif header, including dimensions are untouched, but the JPEG  height/width  are  adjusted.
              This  feature  is  especially  useful  with  newer  Canon  cameras,  that  set the orientation tag
              automatically using a gravity sensor.

       -norot Clears the rotation field in the Exif header without altering the image.   Useful  if  the  images
              were  previously  rotated without clearing the Exif rotation tag, as some image browsers will auto
              rotate images when the rotation tag is set.  Sometimes, thumbnails and rotation  tags can get very
              out  of  sync from manipulation with various tools.  To reset it all use -norot with -rgt to clear
              this out.

OUTPUT VERBOSITY CONTROL

       -h     Displays summary of command line options.

       -v     Makes the program even more verbose than it already  is.   Like  DOS  programs,  and  unlike  UNIX
              programs, Jhead gives feedback as to what it is doing, even when nothing goes wrong.  Windows user
              that I am, when something doesn't give me feedback for 20 seconds, I assume its crashed.

       -q     No output on success, more like Unix programs.

       -V     Print version info and compilation date.  -exifmap Show a map of the bytes  in  the  exif  header.
              Useful when analyzing strange exif headers, not of much use to non software developers.

       -se    Suppress error messages relating to corrupt Exif header structure.

       -c     Concise output.  This causes picture info to be summarized on one line instead of several.  Useful
              for grep-ing through images, as well as importing into spread sheets (data is space delimited with
              quotes as text qualifier).

FILE MATCHING OPTIONS

       -model Restricts  processing  of  files  to  those  whose  camera  model,  as indicated by the Exif image
              information, contains the substring specified in the argument after '-model'.   For  example,  the
              following command will list only images that are from an S100 camera:

              jhead -model S100 *.jpg

              I  use  this  option to restrict my JPEG recompensing to those images that came from my Canon S100
              digicam, (see the -cmd option).

       -exonly
              Skip all files that don't have an Exif header.  Photos straight from a digital camera have an Exif
              header, whereas many photo manipulation tools discard the Exif header.

       -cmd   Executes the specified command on each JPEG file to be processed.

              The Exif section of each file is read before running the command, and reinserted after the command
              finishes.

              The specified command invoked separately for each JPEG that is processed, even if  multiple  files
              are specified (explicitly or by wild card).

              Example use:

              Having a whole directory of photos from my S100, I run the following commands:

              jhead -cmd "mogrify -quality 80 &i" -model S100 *.jpg
              jhead -cmd "jpegtran -progressive &i > &o" *.jpg

              The first command mogrifies all JPEGs in the tree that indicate that they are from a Canon S100 in
              their Exif header to 80% quality at the same resolution.  This is a 'lossy' process, so I only run
              it  on  files  that are from the Canon, and only run it once.  The next command then takes a JPEGs
              and converts them to progressive JPEGs.  The result  is  the  same  images,  with  no  discernible
              differences, stored in half the space.  This produces substantial savings on some cameras.

SEE ALSO

       jpegtran(1), mogrify(1), rdjpgcom(1), wrjpgcom(1)

AUTHOR

       Matthias Wandel

BUGS

       After  jhead  runs a program to rotate or resize an image, the image dimensions and thumbnail in the Exif
       header are not adjusted.

       Modifying of Exif header data is very limited, as Jhead internally only has a read only implementation of
       the  file  system contained in the Exif header.  For example, there is no way to replace the thumbnail or
       edit the Exif comment in the Exif header.  There is also no way to create minimal exif headers.

       Some Canon digital SLR cameras fail to adjust the effective sensor resolution when shooting at less  than
       full  resolution,  causing  jhead  to incorrectly miscalculate the sensor width and 35mm equivalent focal
       length.  The same can result from resizing photos with Photoshop, which will manipulate parts of the exif
       header.  This is often reported as a bug in Jhead, but Jhead can't do much about incorrect data.

       Send bug reports to mwandel at sentex dot net.

COPYING PERMISSIONS

       Jhead  is  'public  domain'.   You  may  freely  copy jhead, and reuse part or all of its code in free or
       proprietary programs.   I do however request that you do not post my e-mail address  in  ways  that  spam
       robots can harvest it.