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JHEAD(1)		    General Commands Manual		      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, re-
       moving the thumbnail, or	transferring Exif headers back into edited im-
       ages  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	'&' 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  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 sec-
	      tions 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  op-
	      tions.

       -mkexif
	      Creates minimal exif header. Exif	header contains	date/time, and
	      empty thumbnail fields only. Date/time set to file time  by  de-
	      fault.  Use with -rgt option if you want the exif	header to con-
	      tain 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 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	YYYYM-
	      MDD-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  sys-
	      tems.

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

	      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, in-
	      cluding  "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 in-
	      correctly, 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,
	      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 '&' 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	Image-
	      Magick) to regenerate the	thumbnail.  This only works if the im-
	      age 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 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  im-
	      ages, as well as importing into spread sheets (data is space de-
	      limited 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

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

       -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 *.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  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  di-
       mensions	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 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.

jhead 3.04			  22 Nov 2019			      JHEAD(1)

NAME | SYNOPSIS | DESCRIPTION | GENERAL METADATA OPTIONS | DATE / TIME MANIPULATION OPTIONS | THUMBNAIL MANIPULATION OPTIONS | ROTATION OPTIONS | OUTPUT VERBOSITY CONTROL | FILE MATCHING OPTIONS | SEE ALSO | AUTHOR | BUGS | COPYING PERMISSIONS

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