


JHEAD(1)                                                 JHEAD(1)


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 for-
       mat.

       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 spec-
              ifying  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  origi-
              nals directory by the same name, Both Win32 and most Unix shells
              treat the command line option for the '&' to even be  passed  to
              the program.


       -dc    Delete  comment  field from the JPEG header.  Note that the com-
              ment 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



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JHEAD(1)                                                 JHEAD(1)


              sections intact.

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

       -du    Delete sections of jpeg that are not Exif, not comment, and oth-
              erwise 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 lim-
              ited 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



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JHEAD(1)                                                 JHEAD(1)


              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 con-
              tains 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 strf-
              time 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 cre-
              ated.

              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  cam-
              era  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




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JHEAD(1)                                                 JHEAD(1)


              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  sys-
              tems.


       -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  for-
              wards.   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  "DateTimeDigi-
              tized" (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  speci-
              fied 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,



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JHEAD(1)                                                 JHEAD(1)


              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 interest-
              ing 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 spec-
              ifying  the thumbnail name.  Whenever the name for file contains
              the characters  '&i', jhead will substitute the  original  file-
              name 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 direc-
              tory 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

              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 ImageMag-
              ick) to regenerate the thumbnail.  This only works if the  image
              already contains a thumbnail.



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JHEAD(1)                                                 JHEAD(1)


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 distribu-
              tions.  For windows, you need to get a copy of it.  After  rota-
              tion, the orientation tag of the Exif header is set to '1' (nor-
              mal 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 use-
              ful with newer Canon cameras, that set the orientation tag auto-
              matically 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, thumb-
              nails and rotation  tags can get very out of sync from manipula-
              tion  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 sec-
              onds, 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  struc-
              ture.

       -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 fol-
              lowing  command will list only images that are from an S100 cam-
              era:

              jhead -model S100 *.jpg



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JHEAD(1)                                                 JHEAD(1)


              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  pro-
              cessed.

              The  Exif  section  of each file is read before running the com-
              mand, 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  fol-
              lowing 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  dis-
              cernible  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.



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JHEAD(1)                                                 JHEAD(1)


       Some Canon digital SLR cameras fail to adjust the effective sensor res-
       olution 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.










































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