Provided by: jhead_2.88-2_i386 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 file

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.  Renaming is
              by default restricted to files whose names  consist  largely  of
              digits.   This effectively restricts renaming to files that have
              not already been manually renamed,  as  the  default  sequential
              names  from  digital cameras consist largely of digits.  Use the
              -nf option to force renaming of all  files.   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.

       -nf    Same as ’-n’ but renames files regardless of original file name.

       -ta<+|-><timediff>
              Adjust time stored in the  Exif  header  by  h:mm  backwards  or
              forwards.  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.

              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

              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 -r *.jpg
              jhead -cmd jpegtran -progressive &i > &o -r *.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.