<?php
/**
 * Exifer 1.7
 * Extracts EXIF information from digital photos.
 * 
 * Originally created by:
 * Copyright © 2005 Jake Olefsky
 * http:// www.offsky.com/software/exif/index.php
 * jake@olefsky.com
 * 
 * This program is free software; you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. http:// www.gnu.org/copyleft/gpl.html
 * 
 * SUMMARY:
 * This script will correctly parse all of the EXIF data included in images taken
 * with digital cameras.  It will read the IDF0, IDF1, SubIDF and InteroperabilityIFD
 * fields as well as parsing some of the MakerNote fields that vary depending on
 * camera make and model.  This script parses more tags than the internal PHP exif
 * implementation and it will correctly identify and decode what all the values mean.
 * This version will correctly parse the MakerNote field for Nikon, Olympus, and Canon
 * digital cameras.  Others will follow.
 * 
 * TESTED WITH:
 * - Nikon CoolPix 700
 * - Nikon CoolPix E3200
 * - Nikon CoolPix 4500
 * - Nikon CoolPix 950
 * - Nikon Coolpix 5700
 * - Canon PowerShot S200
 * - Canon PowerShot S110
 * - Olympus C2040Z
 * - Olympus C960
 * - Olumpus E-300
 * - Olympus E-410
 * - Olympus E-500
 * - Olympus E-510
 * - Olympus E-3
 * - Canon Ixus
 * - Canon EOS 300D
 * - Canon Digital Rebel
 * - Canon EOS 10D
 * - Canon PowerShot G2
 * - FujiFilm DX 10
 * - FujiFilm MX-1200
 * - FujiFilm FinePix2400
 * - FujiFilm FinePix2600
 * - FujiFilm FinePix S602
 * - FujiFilm FinePix40i
 * - Sony D700
 * - Sony Cybershot
 * - Kodak DC210
 * - Kodak DC240
 * - Kodak DC4800
 * - Kodak DX3215
 * - Ricoh RDC-5300
 * - Sanyo VPC-G250
 * - Sanyo VPC-SX550
 * - Epson 3100z
 * 
 * VERSION HISTORY:
 * 
 * 1.0    September 23, 2002
 * - First Public Release
 * 
 * 1.1    January 25, 2003
 * 
 * - Gracefully handled the error case where you pass an empty string to this library
 * - Fixed an inconsistency in the Olympus Camera parsing module
 * - Added support for parsing the MakerNote of Canon images.
 * - Modified how the imagefile is opened so it works for windows machines.
 * - Correctly parses the FocalPlaneResolutionUnit and PhotometricInterpretation fields
 * - Negative rational numbers are properly displayed
 * - Strange old cameras that use Motorola endineness are now properly supported
 * - Tested with several more cameras
 * 
 * Potential Problem: Negative Shorts and Negative Longs may not be correctly displayed, but I
 * have not yet found an example of negative shorts or longs being used.
 * 
 * 1.2    March 30, 2003
 * 
 * - Fixed an error that was displayed if you edited your image with WinXP's image viewer
 * - Fixed a bug that caused some images saved from 3rd party software to not parse correctly
 * - Changed the ExposureTime tag to display in fractional seconds rather than decimal
 * - Updated the ShutterSpeedValue tag to have the units of 'sec'
 * - Added support for parsing the MakeNote of FujiFilm images
 * - Added support for parsing the MakeNote of Sanyo images
 * - Fixed a bug with parsing some Olympus MakerNote tags
 * - Tested with several more cameras
 * 
 * 1.3    June 15, 2003
 * 
 * - Fixed Canon MakerNote support for some models
 *   (Canon has very difficult and inconsistent MakerNote syntax)
 * - Negative signed shorts and negative signed longs are properly displayed
 * - Several more tags are defined
 * - More information in my comments about what each tag is
 * - Parses and Displays GPS information if available
 * - Tested with several more cameras
 * 
 * 1.4    September 14, 2003
 * 
 * - This software is now licensed under the GNU General Public License
 * - Exposure time is now correctly displayed when the numerator is 10
 * - Fixed the calculation and display of ShutterSpeedValue, ApertureValue and MaxApertureValue
 * - Fixed a bug with the GPS code
 * - Tested with several more cameras
 * 
 * 	1.5    February 18, 2005
 * 
 * - It now gracefully deals with a passed in file that cannot be found.
 * - Fixed a GPS bug for the parsing of Altitude and other signed rational numbers
 * - Defined more values for Canon cameras.
 * - Added 'bulb' detection for ShutterSpeed
 * -  Made script loading a little faster and less memory intensive.
 * - Bug fixes
 * - Better error reporting
 * - Graceful failure for files with corrupt exif info.
 * - QuickTime (including iPhoto) messes up the Makernote tag for certain photos (no workaround yet)
 * - Now reads exif information when the jpeg markers are out of order
 * - Gives raw data output for IPTC, COM and APP2 fields which are sometimes set by other applications
 * - Improvements to Nikon Makernote parsing
 * 
 * 1.6    March 25th, 2007 [Zenphoto]
 * 
 * - Adopted into the Zenphoto gallery project, at http://www.zenphoto.org
 * - Fixed a bug where strings had trailing null bytes.
 * - Formatted selected strings better.
 * - Added calculation of 35mm-equivalent focal length when possible.
 * - Cleaned up code for readability and efficiency.
 * 
 * 1.7    April 11th, 2008 [Zenphoto]
 * 
 * - Fixed bug with newer Olympus cameras where number of fields was miscalculated leading to bad performance.
 * - More logical fraction calculation for shutter speed.
 * 
 * 2009: For all further changes, see the Zenphoto change logs.
 * 
 */

/**
 * Converts from Intel to Motorola endien.  Just reverses the bytes (assumes hex is passed in)
 * 
 * @staticvar array $cache
 * @param type $intel
 * @return array
 */
function intel2Moto($intel) {
	static $cache = array();
	if (isset($cache[$intel])) {
		return $cache[$intel];
	}

	$cache[$intel] = '';
	$len  = strlen($intel);
	if ($len > 1000) { // an unreasonable length, override it.
		$len = 1000;
	}
	for($i = 0; $i <= $len; $i += 2) {
		$cache[$intel] .= substr($intel, $len-$i, 2);
	}
	return $cache[$intel];
}

/**
 * Looks up the name of the tag
 * 
 * @param string $tag
 * @return string
 */
function lookup_tag($tag) {
	switch($tag) {
		// used by IFD0 'Camera Tags'
		case '000b': $tag = 'ACDComment'; break;               // text string up to 999 bytes long
		case '00fe': $tag = 'ImageType'; break;                // integer -2147483648 to 2147483647
		case '0106': $tag = 'PhotometricInterpret'; break;     // ?? Please send sample image with this tag
		case '010e': $tag = 'ImageDescription'; break;         // text string up to 999 bytes long
		case '010f': $tag = 'Make'; break;                     // text string up to 999 bytes long
		case '0110': $tag = 'Model'; break;                    // text string up to 999 bytes long
		case '0112': $tag = 'Orientation'; break;              // integer values 1-9
		case '0115': $tag = 'SamplePerPixel'; break;           // integer 0-65535
		case '011a': $tag = 'xResolution'; break;              // positive rational number
		case '011b': $tag = 'yResolution'; break;              // positive rational number
		case '011c': $tag = 'PlanarConfig'; break;             // integer values 1-2
		case '0128': $tag = 'ResolutionUnit'; break;           // integer values 1-3
		case '0131': $tag = 'Software'; break;                 // text string up to 999 bytes long
		case '0132': $tag = 'DateTime'; break;                 // YYYY:MM:DD HH:MM:SS
		case '013b': $tag = 'Artist'; break;                   // text string up to 999 bytes long
		case '013c': $tag = 'HostComputer'; break;             // text string
		case '013e': $tag = 'WhitePoint'; break;               // two positive rational numbers
		case '013f': $tag = 'PrimaryChromaticities'; break;    // six positive rational numbers
		case '0211': $tag = 'YCbCrCoefficients'; break;        // three positive rational numbers
		case '0213': $tag = 'YCbCrPositioning'; break;         // integer values 1-2
		case '0214': $tag = 'ReferenceBlackWhite'; break;      // six positive rational numbers
		case '8298': $tag = 'Copyright'; break;                // text string up to 999 bytes long
		case '8649': $tag = 'PhotoshopSettings'; break;        // ??
		case '8769': $tag = 'ExifOffset'; break;               // positive integer
		case '8825': $tag = 'GPSInfoOffset'; break;
		case '9286': $tag = 'UserCommentOld'; break;           // ??
		// used by Exif SubIFD 'Image Tags'
		case '829a': $tag = 'ExposureTime'; break;             // seconds or fraction of seconds 1/x
		case '829d': $tag = 'FNumber'; break;                  // positive rational number
		case '8822': $tag = 'ExposureProgram'; break;          // integer value 1-9
		case '8824': $tag = 'SpectralSensitivity'; break;      // ??
		case '8827': $tag = 'ISOSpeedRatings'; break;          // integer 0-65535
		case '8830': $tag = 'SensitivityType'; break;          // integer 0-7
		case '8832': $tag = 'RecommendedExposureIndex'; break; // ???
		case '9000': $tag = 'ExifVersion'; break;              // ??
		case '9003': $tag = 'DateTimeOriginal'; break;         // YYYY:MM:DD HH:MM:SS
		case '9004': $tag = 'DateTimeDigitized'; break;        // YYYY:MM:DD HH:MM:SS
		case '9101': $tag = 'ComponentsConfiguration'; break;  // ??
		case '9102': $tag = 'CompressedBitsPerPixel'; break;   // positive rational number
		case '9201': $tag = 'ShutterSpeedValue'; break;        // seconds or fraction of seconds 1/x
		case '9202': $tag = 'ApertureValue'; break;            // positive rational number
		case '9203': $tag = 'BrightnessValue'; break;          // positive rational number
		case '9204': $tag = 'ExposureBiasValue'; break;        // positive rational number (EV)
		case '9205': $tag = 'MaxApertureValue'; break;         // positive rational number
		case '9206': $tag = 'SubjectDistance'; break;          // positive rational number (meters)
		case '9207': $tag = 'MeteringMode'; break;             // integer 1-6 and 255
		case '9208': $tag = 'LightSource'; break;              // integer 1-255
		case '9209': $tag = 'Flash'; break;                    // integer 1-255
		case '920a': $tag = 'FocalLength'; break;              // positive rational number (mm)
		case '9213': $tag = 'ImageHistory'; break;             // text string up to 999 bytes long
		case '927c': $tag = 'MakerNote'; break;                // a bunch of data
		case '9286': $tag = 'UserComment'; break;              // text string
		case '9290': $tag = 'SubsecTime'; break;               // text string up to 999 bytes long
		case '9291': $tag = 'SubsecTimeOriginal'; break;       // text string up to 999 bytes long
		case '9292': $tag = 'SubsecTimeDigitized'; break;      // text string up to 999 bytes long
		case 'a000': $tag = 'FlashPixVersion'; break;          // ??
		case 'a001': $tag = 'ColorSpace'; break;               // values 1 or 65535
		case 'a002': $tag = 'ExifImageWidth'; break;           // ingeter 1-65535
		case 'a003': $tag = 'ExifImageHeight'; break;          // ingeter 1-65535
		case 'a004': $tag = 'RelatedSoundFile'; break;         // text string 12 bytes long
		case 'a005': $tag = 'ExifInteroperabilityOffset'; break;    // positive integer
		case 'a20c': $tag = 'SpacialFreqResponse'; break;      // ??
		case 'a20b': $tag = 'FlashEnergy'; break;              // positive rational number
		case 'a20e': $tag = 'FocalPlaneXResolution'; break;    // positive rational number
		case 'a20f': $tag = 'FocalPlaneYResolution'; break;    // positive rational number
		case 'a210': $tag = 'FocalPlaneResolutionUnit'; break; // values 1-3
		case 'a214': $tag = 'SubjectLocation'; break;          // two integers 0-65535
		case 'a215': $tag = 'ExposureIndex'; break;            // positive rational number
		case 'a217': $tag = 'SensingMethod'; break;            // values 1-8
		case 'a300': $tag = 'FileSource'; break;               // integer
		case 'a301': $tag = 'SceneType'; break;                // integer
		case 'a302': $tag = 'CFAPattern'; break;               // undefined data type
		case 'a401': $tag = 'CustomerRender'; break;           // values 0 or 1
		case 'a402': $tag = 'ExposureMode'; break;             // values 0-2
		case 'a403': $tag = 'WhiteBalance'; break;             // values 0 or 1
		case 'a404': $tag = 'DigitalZoomRatio'; break;         // positive rational number
		case 'a405': $tag = 'FocalLengthIn35mmFilm'; break;
		case 'a406': $tag = 'SceneCaptureMode'; break;         // values 0-3
		case 'a407': $tag = 'GainControl'; break;              // values 0-4
		case 'a408': $tag = 'Contrast'; break;                 // values 0-2
		case 'a409': $tag = 'Saturation'; break;               // values 0-2
		case 'a40a': $tag = 'Sharpness'; break;                // values 0-2
		case 'a434': $tag = 'LensInfo'; break;

		// used by Interoperability IFD
		case '0001': $tag = 'InteroperabilityIndex'; break;    // text string 3 bytes long
		case '0002': $tag = 'InteroperabilityVersion'; break;  // datatype undefined
		case '1000': $tag = 'RelatedImageFileFormat'; break;   // text string up to 999 bytes long
		case '1001': $tag = 'RelatedImageWidth'; break;        // integer in range 0-65535
		case '1002': $tag = 'RelatedImageLength'; break;       // integer in range 0-65535

		// used by IFD1 'Thumbnail'
		case '0100': $tag = 'ImageWidth'; break;               // integer in range 0-65535
		case '0101': $tag = 'ImageLength'; break;              // integer in range 0-65535
		case '0102': $tag = 'BitsPerSample'; break;            // integers in range 0-65535
		case '0103': $tag = 'Compression'; break;              // values 1 or 6
		case '0106': $tag = 'PhotometricInterpretation'; break;// values 0-4
		case '010e': $tag = 'ThumbnailDescription'; break;     // text string up to 999 bytes long
		case '010f': $tag = 'ThumbnailMake'; break;            // text string up to 999 bytes long
		case '0110': $tag = 'ThumbnailModel'; break;           // text string up to 999 bytes long
		case '0111': $tag = 'StripOffsets'; break;             // ??
		case '0112': $tag = 'ThumbnailOrientation'; break;     // integer 1-9
		case '0115': $tag = 'SamplesPerPixel'; break;          // ??
		case '0116': $tag = 'RowsPerStrip'; break;             // ??
		case '0117': $tag = 'StripByteCounts'; break;          // ??
		case '011a': $tag = 'ThumbnailXResolution'; break;     // positive rational number
		case '011b': $tag = 'ThumbnailYResolution'; break;     // positive rational number
		case '011c': $tag = 'PlanarConfiguration'; break;      // values 1 or 2
		case '0128': $tag = 'ThumbnailResolutionUnit'; break;  // values 1-3
		case '0201': $tag = 'JpegIFOffset'; break;
		case '0202': $tag = 'JpegIFByteCount'; break;
		case '0212': $tag = 'YCbCrSubSampling'; break;

		// misc
		case '00ff': $tag = 'SubfileType'; break;
		case '012d': $tag = 'TransferFunction'; break;
		case '013d': $tag = 'Predictor'; break;
		case '0142': $tag = 'TileWidth'; break;
		case '0143': $tag = 'TileLength'; break;
		case '0144': $tag = 'TileOffsets'; break;
		case '0145': $tag = 'TileByteCounts'; break;
		case '014a': $tag = 'SubIFDs'; break;
		case '015b': $tag = 'JPEGTables'; break;
		case '828d': $tag = 'CFARepeatPatternDim'; break;
		case '828e': $tag = 'CFAPattern'; break;
		case '828f': $tag = 'BatteryLevel'; break;
		case '83bb': $tag = 'IPTC/NAA'; break;
		case '8773': $tag = 'InterColorProfile'; break;

		case '8828': $tag = 'OECF'; break;
		case '8829': $tag = 'Interlace'; break;
		case '882a': $tag = 'TimeZoneOffset'; break;
		case '882b': $tag = 'SelfTimerMode'; break;
		case '920b': $tag = 'FlashEnergy'; break;
		case '920c': $tag = 'SpatialFrequencyResponse'; break;
		case '920d': $tag = 'Noise'; break;
		case '9211': $tag = 'ImageNumber'; break;
		case '9212': $tag = 'SecurityClassification'; break;
		case '9214': $tag = 'SubjectLocation'; break;
		case '9215': $tag = 'ExposureIndex'; break;
		case '9216': $tag = 'TIFF/EPStandardID'; break;
		case 'a20b': $tag = 'FlashEnergy'; break;

		default: $tag = 'unknown:'.$tag; break;
	}
	return $tag;

}

/**
 * Looks up the datatype
 * 
 * @param type $type
 * @param type $size
 * @return string
 */
function lookup_type(&$type,&$size) {
	switch($type) {
		case '0001': $type = 'UBYTE'; $size=1; break;
		case '0002': $type = 'ASCII'; $size=1; break;
		case '0003': $type = 'USHORT'; $size=2; break;
		case '0004': $type = 'ULONG'; $size=4; break;
		case '0005': $type = 'URATIONAL'; $size=8; break;
		case '0006': $type = 'SBYTE'; $size=1; break;
		case '0007': $type = 'UNDEFINED'; $size=1; break;
		case '0008': $type = 'SSHORT'; $size=2; break;
		case '0009': $type = 'SLONG'; $size=4; break;
		case '000a': $type = 'SRATIONAL'; $size=8; break;
		case '000b': $type = 'FLOAT'; $size=4; break;
		case '000c': $type = 'DOUBLE'; $size=8; break;
		default: $type = 'error:'.$type; $size=0; break;
	}
	return $type;
}

/**
 * truncates unreasonable read data requests.
 * 
 * @param type $bytesofdata
 * @return type
 */
function validSize($bytesofdata) {
	return min(8191,max(0,$bytesofdata));
}

/**
 * processes a irrational number
 * 
 * @param type $data
 * @param type $type
 * @param type $intel
 * @return string
 */
function unRational($data, $type, $intel) {
		$data = bin2hex($data);
		if ($intel == 1) {
			$data = intel2Moto($data);
			$top = hexdec(substr($data,8,8));   // intel stores them bottom-top
			$bottom = hexdec(substr($data,0,8));  // intel stores them bottom-top
		} else {
			$top = hexdec(substr($data,0,8));        // motorola stores them top-bottom
			$bottom = hexdec(substr($data,8,8));      // motorola stores them top-bottom
		}
		if ($type == 'SRATIONAL' && $top > 2147483647) $top = $top - 4294967296;    // this makes the number signed instead of unsigned
		if ($bottom != 0)
			$data=$top/$bottom;
		else
			if ($top == 0)
				$data = 0;
			else
				$data = $top.'/'.$bottom;
	return $data;
}

/**
 * processes a rational number
 * 
 * @param type $data
 * @param type $type
 * @param type $intel
 * @return type
 */
function rational($data, $type, $intel) {
	if (($type == 'USHORT' || $type == 'SSHORT')) {
		$data = substr($data, 0, 2);
	}
	$data = bin2hex($data);
	if ($intel == 1) {
		$data = intel2Moto($data);
	}
	$data = hexdec($data);
	if ($type == 'SSHORT' && $data > 32767)
		$data = $data - 65536;	// this makes the number signed instead of unsigned
	if ($type == 'SLONG' && $data > 2147483647)
		$data = $data - 4294967296;	// this makes the number signed instead of unsigned
	return $data;
}

/**
 * Formats Data for the data type
 * 
 * @param type $type
 * @param type $tag
 * @param type $intel
 * @param type $data
 * @return type
 */
function formatData($type, $tag, $intel, $data) {
	switch ($type) {
		case 'ASCII':
			if (($pos = strpos($data, chr(0))) !== false) { // Search for a null byte and stop there.
				$data = substr($data, 0, $pos);
			}
			if ($tag == '010f')
				$data = ucwords(strtolower(trim($data))); // Format certain kinds of strings nicely (Camera make etc.)
			break;
		case 'URATIONAL':
		case 'SRATIONAL':
			switch ($tag) {
				case '011a': // XResolution
				case '011b': // YResolution
					$data = round(unRational($data,$type,$intel)).' dots per ResolutionUnit';
					break;
				case '829a': // Exposure Time
					$data = formatExposure(unRational($data,$type,$intel));
					break;
				case '829d': // FNumber
					$data = 'f/'.round(unRational($data,$type,$intel),2);
					break;
				case '9204': // ExposureBiasValue
					$data = round(unRational($data,$type,$intel), 2) . ' EV';
					break;
				case '9205': // ApertureValue
				case '9202': // MaxApertureValue
					// ApertureValue is given in the APEX Mode. Many thanks to Matthieu Froment for this code
					// The formula is : Aperture = 2*log2(FNumber) <=> FNumber = e((Aperture.ln(2))/2)
					$datum = exp((unRational($data,$type,$intel)*log(2))/2);
					$data = 'f/'.round($datum, 1);// Focal is given with a precision of 1 digit.
					break;
				case '920a': // FocalLength
					$data = unRational($data,$type,$intel).' mm';
					break;
				case '9201': // ShutterSpeedValue
					// The ShutterSpeedValue is given in the APEX mode. Many thanks to Matthieu Froment for this code
					// The formula is : Shutter = - log2(exposureTime) (Appendix C of EXIF spec.)
					// Where shutter is in APEX, log2(exposure) = ln(exposure)/ln(2)
					// So final formula is : exposure = exp(-ln(2).shutter)
					// The formula can be developed : exposure = 1/(exp(ln(2).shutter))
					$datum = exp(unRational($data,$type,$intel) * log(2));
					if ($datum != 0) $datum = 1/$datum;
					$data = formatExposure($datum);
					break;
				default:
					$data = unRational($data,$type,$intel);
					break;
			}
			break;
		case 'USHORT':
		case 'SSHORT':
		case 'ULONG':
		case 'SLONG':
		case 'FLOAT':
		case 'DOUBLE':
			$data = rational($data,$type,$intel);
			switch ($tag) {
				case '0112':	// Orientation
					// Example of how all of these tag formatters should be...
					switch ($data) {
						case 0	:		// not set, presume normal
						case 1  :   $data = gettext('1: Normal (0 deg)');      break;
						case 2  :   $data = gettext('2: Mirrored');            break;
						case 3  :   $data = gettext('3: Upside-down');          break;
						case 4  :   $data = gettext('4: Upside-down Mirrored'); break;
						case 5  :   $data = gettext('5: 90 deg CW Mirrored');  break;
						case 6  :   $data = gettext('6: 90 deg CCW');          break;
						case 7  :   $data = gettext('7: 90 deg CCW Mirrored'); break;
						case 8  :   $data = gettext('8: 90 deg CW');           break;
						default :   $data = sprintf(gettext('%d: Unknown'),$data);	break;
					}
					break;
				case '0128':	// ResolutionUnit
				case 'a210':	// FocalPlaneResolutionUnit
				case '0128':	// ThumbnailResolutionUnit
					switch ($data) {
						case 1:	$data = gettext('No Unit');	break;
						case 2:	$data = gettext('Inch');	break;
						case 3:	$data = gettext('Centimeter');	break;
						case 4:	$data = gettext('Millimeter');	break;
						case 5:	$data = gettext('Micrometer');	break;
					}
					break;
				case '0213':	// YCbCrPositioning
					switch ($data) {
						case 1:	$data = gettext('Center of Pixel Array');	break;
						case 2:	$data = gettext('Datum Point');	break;
					}
					break;
				case '8822':	// ExposureProgram
					switch ($data) {
						case 1:		$data = gettext('Manual');	break;
						case 2:		$data = gettext('Program');	break;
						case 3:		$data = gettext('Aperture Priority');	break;
						case 4:		$data = gettext('Shutter Priority');	break;
						case 5:		$data = gettext('Program Creative');	break;
						case 6:		$data = gettext('Program Action');	break;
						case 7:		$data = gettext('Portrait');	break;
						case 8:		$data = gettext('Landscape');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case '8830':	// SensitivityType
					switch ($data) {
						case 1:		$data = gettext('Standard Output Sensitivity');	break;
						case 2:		$data = gettext('Recommended Exposure Index');	break;
						case 3:		$data = gettext('ISO Speed');	break;
						case 4:		$data = gettext('Standard Output Sensitivity and Recommended Exposure Index');	break;
						case 5:		$data = gettext('Standard Output Sensitivity and ISO Speed');	break;
						case 6:		$data = gettext('Recommended Exposure Index and ISO Speed');	break;
						case 7:		$data = gettext('Standard Output Sensitivity, Recommended Exposure Index and ISO Speed');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case '9207':	// MeteringMode
					switch ($data) {
						case 1:		$data = gettext('Average');	break;
						case 2:		$data = gettext('Center Weighted Average');	break;
						case 3:		$data = gettext('Spot');	break;
						case 4:		$data = gettext('Multi-Spot');	break;
						case 5:		$data = gettext('Pattern');	break;
						case 6:		$data = gettext('Partial');	break;
						case 255:	$data = gettext('Other');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case '9208':	// LightSource
					switch ($data) {
						case 1:			$data = gettext('Daylight');	break;
						case 2:			$data = gettext('Fluorescent');	break;
						case 3:			$data = gettext('Tungsten');	break;	// 3 Tungsten (Incandescent light)
													// 4 Flash
													// 9 Fine Weather
						case 10:		$data = gettext('Flash');	break;	// 10 Cloudy Weather
													// 11 Shade
													// 12 Daylight Fluorescent (D 5700 - 7100K)
													// 13 Day White Fluorescent (N 4600 - 5400K)
													// 14 Cool White Fluorescent (W 3900 -4500K)
													// 15 White Fluorescent (WW 3200 - 3700K)
													// 10 Flash
						case 17:		$data = gettext('Standard Light A');	break;
						case 18:		$data = gettext('Standard Light B');	break;
						case 19:		$data = gettext('Standard Light C');	break;
						case 20:		$data = gettext('D55');	break;
						case 21:		$data = gettext('D65');	break;
						case 22:		$data = gettext('D75');	break;
						case 23:		$data = gettext('D50');	break;
						case 24:		$data = gettext('ISO Studio Tungsten');	break;
						case 255:		$data = gettext('Other');	break;
						default:		$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case '9209':	// Flash
					switch ($data) {


						case 0:
						case 16:
						case 24:
						case 32:
						case 64:
						case 80:		$data = gettext('No Flash');	break;
						case 1:			$data = gettext('Flash');	break;
						case 5:			$data = gettext('Flash, strobe return light not detected');	break;
						case 7:			$data = gettext('Flash, strobe return light detected');	break;
						case 9:			$data = gettext('Compulsory Flash');	break;
						case 13:		$data = gettext('Compulsory Flash, Return light not detected');	break;
						case 15:		$data = gettext('Compulsory Flash, Return light detected');	break;
						case 25:		$data = gettext('Flash, Auto-Mode');	break;
						case 29:		$data = gettext('Flash, Auto-Mode, Return light not detected');	break;
						case 31:		$data = gettext('Flash, Auto-Mode, Return light detected');	break;
						case 65:		$data = gettext('Red Eye');	break;
						case 69:		$data = gettext('Red Eye, Return light not detected');	break;
						case 71:		$data = gettext('Red Eye, Return light detected');	break;
						case 73:		$data = gettext('Red Eye, Compulsory Flash');	break;
						case 77:		$data = gettext('Red Eye, Compulsory Flash, Return light not detected');	break;
						case 79:		$data = gettext('Red Eye, Compulsory Flash, Return light detected');	break;
						case 89:		$data = gettext('Red Eye, Auto-Mode');	break;
						case 93:		$data = gettext('Red Eye, Auto-Mode, Return light not detected');	break;
						case 95:		$data = gettext('Red Eye, Auto-Mode, Return light detected');	break;
						default:		$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case 'a001':	// ColorSpace
					if ($data == 1)         $data = gettext('sRGB');
					else                    $data = gettext('Uncalibrated');
					break;
				case 'a002':	// ExifImageWidth
				case 'a003':	// ExifImageHeight
					$data = $data. ' '.gettext('pixels');
					break;
				case '0103':	// Compression
					switch ($data) {
						case 1:		$data = gettext('No Compression');	break;
						case 6:		$data = gettext('Jpeg Compression');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case 'a217':	// SensingMethod
					switch ($data) {
						case 1:		$data = gettext('Not defined');	break;
						case 2:		$data = gettext('One Chip Color Area Sensor');	break;
						case 3:		$data = gettext('Two Chip Color Area Sensor');	break;
						case 4:		$data = gettext('Three Chip Color Area Sensor');	break;
						case 5:		$data = gettext('Color Sequential Area Sensor');	break;
						case 7:		$data = gettext('Trilinear Sensor');	break;
						case 8:		$data = gettext('Color Sequential Linear Sensor');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				case '0106':	// PhotometricInterpretation
					switch ($data) {
						case 1:		$data = gettext('Monochrome');	break;
						case 2:		$data = gettext('RGB');	break;
						case 6:		$data = gettext('YCbCr');	break;
						default:	$data = gettext('Unknown').': '.$data;	break;
					}
					break;
				//case "a408":	// Contrast
				//case "a40a":	//Sharpness
				//	switch($data) {
				//		case 0: $data="Normal"; break;
				//		case 1: $data="Soft"; break;
				//		case 2: $data="Hard"; break;
				//		default: $data="Unknown"; break;
				//	}
				//	break;
				//case "a409":	// Saturation
				//	switch($data) {
				//		case 0: $data="Normal"; break;
				//		case 1: $data="Low saturation"; break;
				//		case 2: $data="High saturation"; break;
				//		default: $data="Unknown"; break;
				//	}
				//	break;
				//case "a402":	// Exposure Mode
				//	switch($data) {
				//		case 0: $data="Auto exposure"; break;
				//		case 1: $data="Manual exposure"; break;
				//		case 2: $data="Auto bracket"; break;
				//		default: $data="Unknown"; break;
				//	}
				//	break;
			}
			break;
		case 'UNDEFINED':
			switch ($tag) {
				case '9000':	// ExifVersion
				case 'a000':	// FlashPixVersion
				case '0002':	// InteroperabilityVersion
					$data=gettext('version').' '.$data/100;
					break;
				case 'a300':	// FileSource
					$data = bin2hex($data);
					$data = str_replace('00','',$data);
					$data = str_replace('03',gettext('Digital Still Camera'),$data);
					break;
				case 'a301':	// SceneType
					$data = bin2hex($data);
					$data = str_replace('00','',$data);
					$data = str_replace('01',gettext('Directly Photographed'),$data);
					break;
				case '9101':	// ComponentsConfiguration
					$data = bin2hex($data);
					$data = str_replace('01','Y',$data);
					$data = str_replace('02','Cb',$data);
					$data = str_replace('03','Cr',$data);
					$data = str_replace('04','R',$data);
					$data = str_replace('05','G',$data);
					$data = str_replace('06','B',$data);
					$data = str_replace('00','',$data);
					break;
				//case "9286":	//UserComment
				//	$encoding	= rtrim(substr($data, 0, 8));
				//	$data		= rtrim(substr($data, 8));
				//	break;
			}
			break;
		default:
			$data = bin2hex($data);
			if ($intel == 1) $data = intel2Moto($data);
			break;
	}
	return $data;
}

/**
 * 
 * @param type $data
 * @return type
 */
function formatExposure($data) {
	if (strpos($data, '/') === false) {
		if ($data >= 1) {
			return round($data, 2) . ' sec';
		} else {
			$n = 0;
			$d = 0;
			ConvertToFraction($data, $n, $d);
			return $n . '/' . $d . ' sec';
		}
	} else {
		return gettext('Bulb');
	}
}

/**
 * Reads one standard IFD entry
 * 
 * @param type $result
 * @param type $in
 * @param type $seek
 * @param type $intel
 * @param type $ifd_name
 * @param type $globalOffset
 * @return type
 */
function read_entry(&$result, $in, $seek, $intel, $ifd_name, $globalOffset) {
	if (feof($in)) { // test to make sure we can still read.
		$result['Errors'] = $result['Errors'] + 1;
		return;
	}
	
	// 2 byte tag
	$tag = bin2hex(fread($in, 2));
	if ($intel == 1)
		$tag = intel2Moto($tag);
	$tag_name = lookup_tag($tag);

	// 2 byte datatype
	$type = bin2hex(fread($in, 2));
	if ($intel == 1)
		$type = intel2Moto($type);
	lookup_type($type, $size);

	if (strpos($tag_name, 'unknown:') !== false && strpos($type, 'error:') !== false) { // we have an error
		$result['Errors'] = $result['Errors'] + 1;
		return;
	}

	// 4 byte number of elements
	$count = bin2hex(fread($in, 4));
	if ($intel == 1)
		$count = intel2Moto($count);
	$bytesofdata = validSize($size * hexdec($count));

	// 4 byte value or pointer to value if larger than 4 bytes
	$value = fread($in, 4);

	if ($bytesofdata <= 4) {	 // if datatype is 4 bytes or less, its the value
		$data = substr($value, 0, $bytesofdata);
	} else if ($bytesofdata < 100000) {				// otherwise its a pointer to the value, so lets go get it
		$value = bin2hex($value);
		if ($intel == 1)
			$value = intel2Moto($value);
		$v = fseek($seek, $globalOffset + hexdec($value));	// offsets are from TIFF header which is 12 bytes from the start of the file
		if ($v == 0) {
			$data = fread($seek, $bytesofdata);
		} else if ($v == -1) {
			$result['Errors'] = $result['Errors'] + 1;
		}
	} else { // bytesofdata was too big, so the exif had an error
		$result['Errors'] = $result['Errors'] + 1;
		return;
	}
	if ($tag_name == 'MakerNote') { // if its a maker tag, we need to parse this specially
		$make = '';
		if (array_key_exists('Make', $result['IFD0'])) {
			$make = $result['IFD0']['Make'];
		}
		if ($result['VerboseOutput'] == 1) {
			$result[$ifd_name]['MakerNote']['RawData'] = $data;
		}
		if (preg_match('/NIKON/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/nikon.php');
			parseNikon($data, $result);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else if (preg_match('/OLYMPUS/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/olympus.php');
			parseOlympus($data, $result, $seek, $globalOffset);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else if (preg_match('/Canon/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/canon.php');
			parseCanon($data, $result, $seek, $globalOffset);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else if (preg_match('/FUJIFILM/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/fujifilm.php');
			parseFujifilm($data, $result);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else if (preg_match('/SANYO/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/sanyo.php');
			parseSanyo($data, $result, $seek, $globalOffset);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else if (preg_match('/Panasonic/i', $make)) {
			require_once(dirname(__FILE__) . '/makers/panasonic.php');
			parsePanasonic($data, $result, $seek, $globalOffset);
			$result[$ifd_name]['KnownMaker'] = 1;
		} else {
			$result[$ifd_name]['KnownMaker'] = 0;
		}
	} else if ($tag_name == 'GPSInfoOffset') {
		require_once(dirname(__FILE__) . '/makers/gps.php');
		$formated_data = formatData($type, $tag, $intel, $data);
		$result[$ifd_name]['GPSInfo'] = $formated_data;
		parseGPS($data, $result, $formated_data, $seek, $globalOffset);
	} else {
		// Format the data depending on the type and tag
		$formated_data = formatData($type, $tag, $intel, $data);

		$result[$ifd_name][$tag_name] = $formated_data;

		if ($result['VerboseOutput'] == 1) {
			if ($type == 'URATIONAL' || $type == 'SRATIONAL' || $type == 'USHORT' || $type == 'SSHORT' || $type == 'ULONG' || $type == 'SLONG' || $type == 'FLOAT' || $type == 'DOUBLE') {
				$data = bin2hex($data);
				if ($intel == 1)
					$data = intel2Moto($data);
			}
			$result[$ifd_name][$tag_name . '_Verbose']['RawData'] = $data;
			$result[$ifd_name][$tag_name . '_Verbose']['Type'] = $type;
			$result[$ifd_name][$tag_name . '_Verbose']['Bytes'] = $bytesofdata;
		}
	}
}

/**
 * Pass in a file and this reads the EXIF data
 * 
 * Usefull resources
 * 
 * - http:// www.ba.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
 * - http:// www.w3.org/Graphics/JPEG/jfif.txt
 * - http:// exif.org/
 * - http:// www.ozhiker.com/electronics/pjmt/library/list_contents.php4
 * - http:// www.ozhiker.com/electronics/pjmt/jpeg_info/makernotes.html
 * - http:// pel.sourceforge.net/
 * - http:// us2.php.net/manual/en/function.exif-read-data.php
 * 
 * @param string $path
 * @param int $verbose
 * @return int
 */
function read_exif_data_raw($path, $verbose) {
	$result = array();
	if ($path == '' || $path == 'none')
		return;

	$in = @fopen($path, 'rb'); // the b is for windows machines to open in binary mode
	$seek = @fopen($path, 'rb'); // There may be an elegant way to do this with one file handle.

	$globalOffset = 0;

	if (!isset($verbose))
		$verbose = 0;

	$result['VerboseOutput'] = $verbose;
	$result['Errors'] = 0;

	if (!$in || !$seek) {	// if the path was invalid, this error will catch it
		$result['Errors'] = 1;
		$result['Error'][$result['Errors']] = gettext('The file could not be found.');
		return $result;
	}

	$GLOBALS['exiferFileSize'] = filesize($path);

	// First 2 bytes of JPEG are 0xFFD8
	$data = bin2hex(fread($in, 2));
	if ($data == 'ffd8') {
		$result['ValidJpeg'] = 1;
	} else {
		$result['ValidJpeg'] = 0;
		fseek($in, 0);
	}

	$result['ValidIPTCData'] = 0;
	$result['ValidJFIFData'] = 0;
	$result['ValidEXIFData'] = 0;
	$result['ValidAPP2Data'] = 0;
	$result['ValidCOMData'] = 0;

	if ($result['ValidJpeg'] == 1) {

		// LOOP THROUGH MARKERS TILL ffe1 EXIF Marker
		$abortCount = 0;
		$header = '\0';
		while (!feof($in) && ++$abortCount < 200) {

			// Next 2 bytes are MARKER tag (0xFF**)
			$data = bin2hex(fread($in, 2));
			$size = bin2hex(fread($in, 2));

			if ($data == 'ffc0' || $data == 'ffd9') { // Start Of Frame Marker or End of Image Marker
				break;
			} else if ($data == 'ffe0') {						 // JFIF Marker
				$result['ValidJFIFData'] = 1;
				$result['JFIF']['Size'] = hexdec($size);

				if (hexdec($size) - 2 > 0) {
					$data = fread($in, hexdec($size) - 2);
					$result['JFIF']['Data'] = $data;
				}

				$result['JFIF']['Identifier'] = substr($data, 0, 5);
				$result['JFIF']['ExtensionCode'] = bin2hex(substr($data, 6, 1));

				$globalOffset += hexdec($size) + 2;
			} else if ($data == 'ffe1') {						 // APP1 Marker : EXIF Metadata(TIFF IFD format) or JPEG Thumbnail or Adobe XMP
				$header = fread($in, 6);											// Exif block starts with 'Exif\0\0' header
				if ($header == "Exif\0\0") {										// EXIF Marker ?
					$result['ValidEXIFData'] = 1;
					$result['ValidAPP1Data'] = 1;
					$result['APP1']['Size'] = hexdec($size);
					break;
				} else {
					if (hexdec($size) - 2 > 0) {
						$data = fread($in, hexdec($size) - 2 - 6); // skip XMP or Thumbnail data, and loop again
					}
					$globalOffset += hexdec($size) + 2;
				}
			} else if ($data == 'ffe2') {						 // APP2 Marker : EXIF extension
				$result['ValidAPP2Data'] = 1;
				$result['APP2']['Size'] = hexdec($size);

				if (hexdec($size) - 2 > 0) {
					$data = fread($in, hexdec($size) - 2);
					$result['APP2']['Data'] = $data;
				}
				$globalOffset += hexdec($size) + 2;
			} else if ($data == 'ffed') {						 // IPTC Marker
				$result['ValidIPTCData'] = 1;
				$result['IPTC']['Size'] = hexdec($size);

				if (hexdec($size) - 2 > 0) {
					$data = fread($in, hexdec($size) - 2);
					$result['IPTC']['Data'] = $data;
				}
				$globalOffset += hexdec($size) + 2;
			} else if ($data == 'fffe') {						 // Comment extension Marker
				$result['ValidCOMData'] = 1;
				$result['COM']['Size'] = hexdec($size);

				if (hexdec($size) - 2 > 0) {
					$data = fread($in, hexdec($size) - 2);
					$result['COM']['Data'] = $data;
				}
				$globalOffset += hexdec($size) + 2;
			} else {																	// unknown Marker
				if (hexdec($size) - 2 > 0) {
					$data = fread($in, hexdec($size) - 2);
				}
				$globalOffset += hexdec($size) + 2;
			}
		}
		// END MARKER LOOP

		if ($header != "Exif\0\0") {
			fclose($in);
			fclose($seek);
			return $result;
		}
	} // END IF ValidJpeg
	// Then theres a TIFF header with 2 bytes of endieness (II or MM)
	$header = fread($in, 2);
	if ($header === 'II') {
		$intel = 1;
		$result['Endien'] = 'Intel';
	} else if ($header === 'MM') {
		$intel = 0;
		$result['Endien'] = 'Motorola';
	} else {
		$intel = 1; // not sure what the default should be, but this seems reasonable
		$result['Endien'] = 'Unknown';
	}

	// 2 bytes of 0x002a
	$tag = bin2hex(fread($in, 2));

	// Then 4 bytes of offset to IFD0 (usually 8 which includes all 8 bytes of TIFF header)
	$offset = bin2hex(fread($in, 4));
	if ($intel == 1)
		$offset = intel2Moto($offset);

	// Check for extremely large values here
	if (hexdec($offset) > 100000) {
		$result['ValidEXIFData'] = 0;
		fclose($in);
		fclose($seek);
		return $result;
	}

	if (hexdec($offset) > 8)
		$unknown = fread($in, hexdec($offset) - 8); // fixed this bug in 1.3

		
// add 12 to the offset to account for TIFF header
	if ($result['ValidJpeg'] == 1) {
		$globalOffset += 12;
	}


	//===========================================================
	// Start of IFD0
	$num = bin2hex(fread($in, 2));
	if ($intel == 1)
		$num = intel2Moto($num);
	$num = hexdec($num);
	$result['IFD0NumTags'] = $num;

	if ($num < 1000) { // 1000 entries is too much and is probably an error.
		for ($i = 0; $i < $num; $i++) {
			read_entry($result, $in, $seek, $intel, 'IFD0', $globalOffset);
		}
	} else {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = 'Illegal size for IFD0';
	}

	// store offset to IFD1
	$offset = bin2hex(fread($in, 4));
	if ($intel == 1)
		$offset = intel2Moto($offset);
	$result['IFD1Offset'] = hexdec($offset);

	// Check for SubIFD
	if (!isset($result['IFD0']['ExifOffset']) || $result['IFD0']['ExifOffset'] == 0) {
		fclose($in);
		fclose($seek);
		return $result;
	}

	// seek to SubIFD (Value of ExifOffset tag) above.
	$ExitOffset = $result['IFD0']['ExifOffset'];
	$v = fseek($in, $globalOffset + $ExitOffset);
	if ($v == -1) {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Could not Find SubIFD');
	}

	//===========================================================
	// Start of SubIFD
	$num = bin2hex(fread($in, 2));
	if ($intel == 1)
		$num = intel2Moto($num);
	$num = hexdec($num);
	$result['SubIFDNumTags'] = $num;

	if ($num < 1000) { // 1000 entries is too much and is probably an error.
		for ($i = 0; $i < $num; $i++) {
			read_entry($result, $in, $seek, $intel, 'SubIFD', $globalOffset);
		}
	} else {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Illegal size for SubIFD');
	}

	// Add the 35mm equivalent focal length:
	if (isset($result['IFD0']['FocalLengthIn35mmFilm']) && !isset($result['SubIFD']['FocalLengthIn35mmFilm'])) { // found in the wrong place
		$result['SubIFD']['FocalLengthIn35mmFilm'] = $result['IFD0']['FocalLengthIn35mmFilm'];
	}
	if (!isset($result['SubIFD']['FocalLengthIn35mmFilm'])) {
		$result['SubIFD']['FocalLengthIn35mmFilm'] = get35mmEquivFocalLength($result);
	}

	// Check for IFD1
	if (!isset($result['IFD1Offset']) || $result['IFD1Offset'] == 0) {
		fclose($in);
		fclose($seek);
		return $result;
	}
	// seek to IFD1
	$v = fseek($in, $globalOffset + $result['IFD1Offset']);
	if ($v == -1) {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Could not Find IFD1');
	}

	//===========================================================
	// Start of IFD1
	$num = bin2hex(fread($in, 2));
	if ($intel == 1)
		$num = intel2Moto($num);
	$num = hexdec($num);
	$result['IFD1NumTags'] = $num;

	if ($num < 1000) { // 1000 entries is too much and is probably an error.
		for ($i = 0; $i < $num; $i++) {
			read_entry($result, $in, $seek, $intel, 'IFD1', $globalOffset);
		}
	} else {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Illegal size for IFD1');
	}
	// If verbose output is on, include the thumbnail raw data...
	if ($result['VerboseOutput'] == 1 && $result['IFD1']['JpegIFOffset'] > 0 && $result['IFD1']['JpegIFByteCount'] > 0) {
		$v = fseek($seek, $globalOffset + $result['IFD1']['JpegIFOffset']);
		if ($v == 0) {
			$data = fread($seek, $result['IFD1']['JpegIFByteCount']);
		} else if ($v == -1) {
			$result['Errors'] = $result['Errors'] + 1;
		}
		$result['IFD1']['ThumbnailData'] = $data;
	}


	// Check for Interoperability IFD
	if (!isset($result['SubIFD']['ExifInteroperabilityOffset']) || $result['SubIFD']['ExifInteroperabilityOffset'] == 0) {
		fclose($in);
		fclose($seek);
		return $result;
	}
	// Seek to InteroperabilityIFD
	$v = fseek($in, $globalOffset + $result['SubIFD']['ExifInteroperabilityOffset']);
	if ($v == -1) {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Could not Find InteroperabilityIFD');
	}

	//===========================================================
	// Start of InteroperabilityIFD
	$num = bin2hex(fread($in, 2));
	if ($intel == 1)
		$num = intel2Moto($num);
	$num = hexdec($num);
	$result['InteroperabilityIFDNumTags'] = $num;

	if ($num < 1000) { // 1000 entries is too much and is probably an error.
		for ($i = 0; $i < $num; $i++) {
			read_entry($result, $in, $seek, $intel, 'InteroperabilityIFD', $globalOffset);
		}
	} else {
		$result['Errors'] = $result['Errors'] + 1;
		$result['Error'][$result['Errors']] = gettext('Illegal size for InteroperabilityIFD');
	}
	fclose($in);
	fclose($seek);
	return $result;
}

/**
 * Converts a floating point number into a simple fraction.
 * 
 * @param type $v
 * @param type $n
 * @param type $d
 * @return type
 */
function ConvertToFraction($v, &$n, &$d) {
	if ($v == 0) {
		$n = 0;
		$d = 1;
		return;
	}
	for ($n = 1; $n < 100; $n++) {
		$v1 = 1 / $v * $n;
		$d = round($v1, 0);
		if (abs($d - $v1) < 0.02)
			return; // within tolarance
	}
}

/**
 * Calculates the 35mm-equivalent focal length from the reported sensor resolution
 * @author Tristan Harward (trisweb)
 * 
 * @param array $result
 * 
 * @return int
 */
function get35mmEquivFocalLength(&$result) {
	if (isset($result['SubIFD']['ExifImageWidth'])) {
		$width = $result['SubIFD']['ExifImageWidth'];
	} else {
		$width = 0;
	}
	if (isset($result['SubIFD']['ExifImageHeight'])) {
		$height = $result['SubIFD']['ExifImageHeight'];
	} else {
		$height = 0;
	}
	if (isset($result['SubIFD']['FocalPlaneResolutionUnit'])) {
		$units = $result['SubIFD']['FocalPlaneResolutionUnit'];
	} else {
		$units = '';
	}
	$unitfactor = 1;
	switch ($units) {
		case gettext('Inch') : 
			$unitfactor = 25.4;
			break;
		case gettext('Centimeter') : 
			$unitfactor = 10;
			break;
		case gettext('Millimeter') : 
			$unitfactor = 1;
			break;
		case gettext('Micrometer') : 
			$unitfactor = 0.001;
			break;
		case gettext('No Unit') : 
			$unitfactor = 25.4;
			break;
		default : 
			$unitfactor = 25.4;
	}
	if (isset($result['SubIFD']['FocalPlaneXResolution'])) {
		$xres = $result['SubIFD']['FocalPlaneXResolution'];
	} else {
		$xres = '';
	}
	if (isset($result['SubIFD']['FocalPlaneYResolution'])) {
		$yres = $result['SubIFD']['FocalPlaneYResolution'];
	} else {
		$yres = '';
	}
	if (isset($result['SubIFD']['FocalLength'])) {
		$fl = $result['SubIFD']['FocalLength'];
	} else {
		$fl = 0;
	}
	if (!empty($width) && !empty($height) && !empty($xres) && !empty($yres) && !empty($units) && !empty($fl)) {
		// Calculate CCD diagonal using Pythagoras' theorem (a² + b² = c²)
		$diagccd = sqrt(
				  pow(((intval($width) * $unitfactor) / $xres), 2)
			 	+ pow(((intval($height) * $unitfactor) / $yres), 2)
				);
		// Calculate 35mm diagonal using Pythagoras' theorem
		$diag35mm = sqrt(1872);   // 36² + 24² = 1872
		$cropfactor = $diag35mm / $diagccd;
		$equivfl = intval($fl) * $cropfactor;
		return $equivfl;
	}
	return null;
}
