Provided by: jhead_3.03-1_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 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.  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.