:
##########################################################################
# Title      :	exifinfo - print EXIF information of an image file
# Author     :	Heiner Steven <heiner.steven@odn.de>
# Date       :	2004-01-09
# Category   :	Graphics
# Requires   :	identify
# SCCS-Id.   :	@(#) exifinfo	1.4 13/05/01
##########################################################################
# Description
#
# Caveats
#    o	EXIF tags that would result in invalid shell variable names
#	should be rewritten, e.g. by replacing invalid characters with a
#	'_' character
#    o	Individual tag names (e.g. "ImageWidth") should be allowed
#
# Bibiliography
#    o	exif.org: "Specifications"
#	http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
#    o	TsuruZoh Tachibanaya: "Description of Exif file format",
#	http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
#
# Output example (identify 5.5.4)
#   EXIF_Make='EASTMAN KODAK COMPANY'
#   EXIF_Model='KODAK DX4530 ZOOM DIGITAL CAMERA'
#   EXIF_Orientation='1'
#   EXIF_XResolution='230/1'
#   EXIF_YResolution='230/1'
#   EXIF_ResolutionUnit='2'
#   EXIF_YCbCrPositioning='1'
#   EXIF_ExifOffset='506'
#   EXIF_ExposureTime='1/30'
#   EXIF_FNumber='28/10'
#   EXIF_ExposureProgram='2'
#   EXIF_ExifVersion='0220'
#   EXIF_DateTimeOriginal='2003:01:03 08:41:52'
#   EXIF_DateTimeDigitized='2003:01:03 08:41:52'
#   EXIF_ComponentsConfiguration='...'
#   EXIF_ShutterSpeedValue='50/10'
#   EXIF_ApertureValue='3/1'
#   EXIF_ExposureBiasValue='0/1000'
#   EXIF_MaxApertureValue='30/10'
#   EXIF_MeteringMode='5'
#   EXIF_LightSource='0'
#   EXIF_Flash='25'
#   EXIF_FocalLength='80/10'
#   EXIF_MakerNote='KDK0002IDX4530  ..'
#   EXIF_FlashPixVersion='0100'
#   EXIF_ColorSpace='1'
#   EXIF_ExifImageWidth='2580'
#   EXIF_ExifImageLength='1932'
#   EXIF_InteroperabilityOffset='2320'
#   EXIF_unknown='R98'
#   EXIF_unknown='0100'
#   EXIF_ExposureIndex='140/1'
#   EXIF_SensingMethod='2'
#   EXIF_FileSource='.'
#   EXIF_SceneType='.'
#   EXIF_unknown='0'
#   EXIF_unknown='0'
#   EXIF_unknown='0'
#   EXIF_unknown='0/100'
#   EXIF_unknown='38'
#   EXIF_unknown='0'
#   EXIF_unknown='1'
#   EXIF_unknown='0'
#   EXIF_unknown='0'
#   EXIF_unknown='0'
#   EXIF_unknown='0'
##########################################################################

PN=`basename "$0"`			# Program name
VER='1.4'

usage () {
    echo >&2 "$PN - print EXIF information of an image file, $VER
usage: $PN [-p prefix] image [image ...]
    -p:  variable prefix (default is \"EXIF_\")

Prints the EXIF information from the image files. The output is printed
as "var=value" pairs in a way suitable as input to the shell, e.g.

	eval \`$PN image.jpg\`

can be used to set variables e.g. \"EXIF_ExifVersion\". Note that EXIF
tags with names that would be invalid shell variable names are silently
ignored."
    exit 1
}

msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

fatal () { msg "$@"; exit 1; }

Prefix=
while getopts :hp: opt
do
    case "$opt" in
    	p)	Prefix=$OPTARG;;
	h)	usage;;
	?)	usage;;
    esac
done
shift `expr $OPTIND - 1`

[ $# -lt 1 ] && usage

prefix=${Prefix:-EXIF_}
info='*'

for file
do
    # Explanation of the "sed" expressions:
    #	 o  remove all lines not containing a "="
    #	 o  remove "exif:" prefix appearing with e.g. identify(1) 6.7.7
    #	 o  remove all lines containing tag names that would form invalid
    #	    shell variable names
    #	 o  quote all apostrophy characters ' as '\''
    #	 o  add an apostrophy at the front and the end of the value
    #	    string
    #    o  write the variable name prefix in front of each variable

    identify -format "%[EXIF:$info]" "$file" |
    	sed \
	    	-e 's/^exif://g'	\
		-e '/^[^=]*$/d'		\
		-e '/[^A-Za-z0-9_=][^=]*=/d'	\
		-e "s/'/'\\\\''/g"	\
		-e "s/=/='/"		\
		-e "s/\$/'/"		\
		-e "s/^/$prefix/"
done