includes/Exif.php

   1 <?php
   2 if (defined('MEDIAWIKI')) {
   3 /**
   4  * @package MediaWiki
   5  * @subpackage Metadata
   6  *
   7  * @author Ævar Arnfjörð Bjarmason <avarab@gmail.com>
   8  * @copyright Copyright © 2005, Ævar Arnfjörð Bjarmason
   9  * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License along
  22  * with this program; if not, write to the Free Software Foundation, Inc.,
  23  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  24  * http://www.gnu.org/copyleft/gpl.html
  25  *
  26  * @link http://exif.org/Exif2-2.PDF The Exif 2.2 specification
  27  * @bug 1555, 1947
  28  */
  29
  30 /**#@+
  31  * Exif tag type definition
  32  */
  33 define('MW_EXIF_BYTE', 1);              # An 8-bit unsigned integer.
  34 define('MW_EXIF_ASCII', 2);             # An 8-bit byte containing one 7-bit ASCII code. The final byte is terminated with NULL.
  35 define('MW_EXIF_SHORT', 3);             # A 16-bit (2-byte) unsigned integer.
  36 define('MW_EXIF_LONG', 4);              # A 32-bit (4-byte) unsigned integer.
  37 define('MW_EXIF_RATIONAL', 5);          # Two LONGs. The first LONG is the numerator and the second LONG expresses the denominator
  38 define('MW_EXIF_UNDEFINED', 7);         # An 8-bit byte that can take any value depending on the field definition
  39 define('MW_EXIF_SLONG', 9);             # A 32-bit (4-byte) signed integer (2's complement notation),
  40 define('MW_EXIF_SRATIONAL', 10);        # Two SLONGs. The first SLONG is the numerator and the second SLONG is the denominator.
  41 /**#@-*/
  42
  43
  44 /**
  45  * @package MediaWiki
  46  * @subpackage Metadata
  47  */
  48 class Exif {
  49         /**#@+
  50          * @var array
  51          */
  52
  53         /**
  54          * Exif tags grouped by category, the tagname itself is the key and the type
  55          * is the value, in the case of more than one possible value type they are
  56          * seperated by commas.
  57          *
  58          * @access private
  59          */
  60         var $mExif;
  61
  62         /**
  63          * A one dimentional array of all Exif tags
  64          */
  65         var $mFlatExif;
  66
  67         /**#@-*/
  68
  69         /**
  70          * Constructor
  71          */
  72         function Exif() {
  73                 /**
  74                  * Page numbers here refer to pages in the EXIF 2.2 standard
  75                  *
  76                  * @link http://exif.org/Exif2-2.PDF The Exif 2.2 specification
  77                  */
  78                 $this->mExif = array(
  79                         # TIFF Rev. 6.0 Attribute Information (p22)
  80                         'tiff' => array(
  81                                 # Tags relating to image structure
  82                                 'structure' => array(
  83                                         'ImageWidth' => MW_EXIF_SHORT.','.MW_EXIF_LONG,         # Image width
  84                                         'ImageLength' => MW_EXIF_SHORT.','.MW_EXIF_LONG,        # Image height
  85                                         'BitsPerSample' => MW_EXIF_SHORT,                       # Number of bits per component
  86                                         # "When a primary image is JPEG compressed, this designation is not"
  87                                         # "necessary and is omitted." (p23)
  88                                         'Compression' => MW_EXIF_SHORT,                         # Compression scheme #p23
  89                                         'PhotometricInterpretation' => MW_EXIF_SHORT,           # Pixel composition #p23
  90                                         'Orientation' => MW_EXIF_SHORT,                         # Orientation of image #p24
  91                                         'SamplesPerPixel' => MW_EXIF_SHORT,                     # Number of components
  92                                         'PlanarConfiguration' => MW_EXIF_SHORT,                 # Image data arrangement #p24
  93                                         'YCbCrSubSampling' => MW_EXIF_SHORT,                    # Subsampling ratio of Y to C #p24
  94                                         'YCbCrPositioning' => MW_EXIF_SHORT,                    # Y and C positioning #p24-25
  95                                         'XResolution' => MW_EXIF_RATIONAL,                      # Image resolution in width direction
  96                                         'YResolution' => MW_EXIF_RATIONAL,                      # Image resolution in height direction
  97                                         'ResolutionUnit' => MW_EXIF_SHORT,                      # Unit of X and Y resolution #(p26)
  98                                 ),
  99
 100                                 # Tags relating to recording offset
 101                                 'offset' => array(
 102                                         'StripOffsets' => MW_EXIF_SHORT.','.MW_EXIF_LONG,                       # Image data location
 103                                         'RowsPerStrip' => MW_EXIF_SHORT.','.MW_EXIF_LONG,                       # Number of rows per strip
 104                                         'StripByteCounts' => MW_EXIF_SHORT.','.MW_EXIF_LONG,                    # Bytes per compressed strip
 105                                         'JPEGInterchangeFormat' => MW_EXIF_SHORT.','.MW_EXIF_LONG,              # Offset to JPEG SOI
 106                                         'JPEGInterchangeFormatLength' => MW_EXIF_SHORT.','.MW_EXIF_LONG,        # Bytes of JPEG data
 107                                 ),
 108
 109                                 # Tags relating to image data characteristics
 110                                 'characteristics' => array(
 111                                         'TransferFunction' => MW_EXIF_SHORT,            # Transfer function
 112                                         'WhitePoint' => MW_EXIF_RATIONAL,               # White point chromaticity
 113                                         'PrimaryChromaticities' => MW_EXIF_RATIONAL,    # Chromaticities of primarities
 114                                         'YCbCrCoefficients' => MW_EXIF_RATIONAL,        # Color space transformation matrix coefficients #p27
 115                                         'ReferenceBlackWhite' => MW_EXIF_RATIONAL       # Pair of black and white reference values
 116                                 ),
 117
 118                                 # Other tags
 119                                 'other' => array(
 120                                         'DateTime' => MW_EXIF_ASCII,            # File change date and time
 121                                         'ImageDescription' => MW_EXIF_ASCII,    # Image title
 122                                         'Make' => MW_EXIF_ASCII,                # Image input equipment manufacturer
 123                                         'Model' => MW_EXIF_ASCII,               # Image input equipment model
 124                                         'Software' => MW_EXIF_ASCII,            # Software used
 125                                         'Artist' => MW_EXIF_ASCII,              # Person who created the image
 126                                         'Copyright' => MW_EXIF_ASCII,           # Copyright holder
 127                                 ),
 128                         ),
 129
 130                         # Exif IFD Attribute Information (p30-31)
 131                         'exif' => array(
 132                                 # Tags relating to version
 133                                 'version' => array(
 134                                         # TODO: NOTE: Nonexistence of this field is taken to mean nonconformance
 135                                         # to the EXIF 2.1 AND 2.2 standards
 136                                         'ExifVersion' => MW_EXIF_UNDEFINED,     # Exif version
 137                                         'FlashpixVersion' => MW_EXIF_UNDEFINED, # Supported Flashpix version #p32
 138                                 ),
 139
 140                                 # Tags relating to Image Data Characteristics
 141                                 'characteristics' => array(
 142                                         'ColorSpace' => MW_EXIF_SHORT,          # Color space information #p32
 143                                 ),
 144
 145                                 # Tags relating to image configuration
 146                                 'configuration' => array(
 147                                         'ComponentsConfiguration' => MW_EXIF_UNDEFINED,         # Meaning of each component #p33
 148                                         'CompressedBitsPerPixel' => MW_EXIF_RATIONAL,           # Image compression mode
 149                                         'PixelYDimension' => MW_EXIF_SHORT.','.MW_EXIF_LONG,    # Valid image width
 150                                         'PixelXDimension' => MW_EXIF_SHORT.','.MW_EXIF_LONG,    # Valind image height
 151                                 ),
 152
 153                                 # Tags relating to related user information
 154                                 'user' => array(
 155                                         'MakerNote' => MW_EXIF_UNDEFINED,                       # Manufacturer notes
 156                                         'UserComment' => MW_EXIF_UNDEFINED,                     # User comments #p34
 157                                 ),
 158
 159                                 # Tags relating to related file information
 160                                 'related' => array(
 161                                         'RelatedSoundFile' => MW_EXIF_ASCII,                    # Related audio file
 162                                 ),
 163
 164                                 # Tags relating to date and time
 165                                 'dateandtime' => array(
 166                                         'DateTimeOriginal' => MW_EXIF_ASCII,                    # Date and time of original data generation #p36
 167                                         'DateTimeDigitized' => MW_EXIF_ASCII,                   # Date and time of original data generation
 168                                         'SubSecTime' => MW_EXIF_ASCII,                          # DateTime subseconds
 169                                         'SubSecTimeOriginal' => MW_EXIF_ASCII,                  # DateTimeOriginal subseconds
 170                                         'SubSecTimeDigitized' => MW_EXIF_ASCII,                 # DateTimeDigitized subseconds
 171                                 ),
 172
 173                                 # Tags relating to picture-taking conditions (p31)
 174                                 'conditions' => array(
 175                                         'ExposureTime' => MW_EXIF_RATIONAL,                     # Exposure time
 176                                         'FNumber' => MW_EXIF_RATIONAL,                          # F Number
 177                                         'ExposureProgram' => MW_EXIF_SHORT,                     # Exposure Program #p38
 178                                         'SpectralSensitivity' => MW_EXIF_ASCII,                 # Spectral sensitivity
 179                                         'ISOSpeedRatings' => MW_EXIF_SHORT,                     # ISO speed rating
 180                                         'OECF' => MW_EXIF_UNDEFINED,                            # Optoelectronic conversion factor
 181                                         'ShutterSpeedValue' => MW_EXIF_SRATIONAL,               # Shutter speed
 182                                         'ApertureValue' => MW_EXIF_RATIONAL,                    # Aperture
 183                                         'BrightnessValue' => MW_EXIF_SRATIONAL,                 # Brightness
 184                                         'ExposureBiasValue' => MW_EXIF_SRATIONAL,               # Exposure bias
 185                                         'MaxApertureValue' => MW_EXIF_RATIONAL,                 # Maximum land aperture
 186                                         'SubjectDistance' => MW_EXIF_RATIONAL,                  # Subject distance
 187                                         'MeteringMode' => MW_EXIF_SHORT,                        # Metering mode #p40
 188                                         'LightSource' => MW_EXIF_SHORT,                         # Light source #p40-41
 189                                         'Flash' => MW_EXIF_SHORT,                               # Flash #p41-42
 190                                         'FocalLength' => MW_EXIF_RATIONAL,                      # Lens focal length
 191                                         'SubjectArea' => MW_EXIF_SHORT,                         # Subject area
 192                                         'FlashEnergy' => MW_EXIF_RATIONAL,                      # Flash energy
 193                                         'SpatialFrequencyResponse' => MW_EXIF_UNDEFINED,        # Spatial frequency response
 194                                         'FocalPlaneXResolution' => MW_EXIF_RATIONAL,            # Focal plane X resolution
 195                                         'FocalPlaneYResolution' => MW_EXIF_RATIONAL,            # Focal plane Y resolution
 196                                         'FocalPlaneResolutionUnit' => MW_EXIF_SHORT,            # Focal plane resolution unit
 197                                         'SubjectLocation' => MW_EXIF_SHORT,                     # Subject location
 198                                         'ExposureIndex' => MW_EXIF_RATIONAL,                    # Exposure index
 199                                         'SensingMethod' => MW_EXIF_SHORT,                       # Sensing method #p46
 200                                         'FileSource' => MW_EXIF_UNDEFINED,                      # File source #p47
 201                                         'SceneType' => MW_EXIF_UNDEFINED,                       # Scene type #p47
 202                                         'CFAPattern' => MW_EXIF_UNDEFINED,                      # CFA pattern
 203                                         'CustomRendered' => MW_EXIF_SHORT,                      # Custom image processing #p48
 204                                         'ExposureMode' => MW_EXIF_SHORT,                        # Exposure mode #p48
 205                                         'WhiteBalance' => MW_EXIF_SHORT,                        # White Balance #p49
 206                                         'DigitalZoomRatio' => MW_EXIF_RATIONAL,                 # Digital zoom ration
 207                                         'FocalLengthIn35mmFilm' => MW_EXIF_SHORT,               # Focal length in 35 mm film
 208                                         'SceneCaptureType' => MW_EXIF_SHORT,                    # Scene capture type #p49
 209                                         'GainControl' => MW_EXIF_RATIONAL,                      # Scene control #p49-50
 210                                         'Contrast' => MW_EXIF_SHORT,                            # Contrast #p50
 211                                         'Saturation' => MW_EXIF_SHORT,                          # Saturation #p50
 212                                         'Sharpness' => MW_EXIF_SHORT,                           # Sharpness #p50
 213                                         'DeviceSettingDescription' => MW_EXIF_UNDEFINED,        # Desice settings description
 214                                         'SubjectDistanceRange' => MW_EXIF_SHORT,                # Subject distance range #p51
 215                                 ),
 216
 217                                 'other' => array(
 218                                         'ImageUniqueID' => MW_EXIF_ASCII,       # Unique image ID
 219                                 ),
 220                         ),
 221
 222                         # GPS Attribute Information (p52)
 223                         'gps' => array(
 224                                 'GPSVersionID' => MW_EXIF_BYTE,                 # GPS tag version
 225                                 'GPSLatitudeRef' => MW_EXIF_ASCII,              # North or South Latitude #p52-53
 226                                 'GPSLatitude' => MW_EXIF_RATIONAL,              # Latitude
 227                                 'GPSLongitudeRef' => MW_EXIF_ASCII,             # East or West Longitude #p53
 228                                 'GPSLongitude' => MW_EXIF_RATIONAL,             # Longitude
 229                                 'GPSAltitudeRef' => MW_EXIF_BYTE,               # Altitude reference
 230                                 'GPSAltitude' => MW_EXIF_RATIONAL,              # Altitude
 231                                 'GPSTimeStamp' => MW_EXIF_RATIONAL,             # GPS time (atomic clock)
 232                                 'GPSSatellites' => MW_EXIF_ASCII,               # Satellites used for measurement
 233                                 'GPSStatus' => MW_EXIF_ASCII,                   # Receiver status #p54
 234                                 'GPSMeasureMode' => MW_EXIF_ASCII,              # Measurement mode #p54-55
 235                                 'GPSDOP' => MW_EXIF_RATIONAL,                   # Measurement precision
 236                                 'GPSSpeedRef' => MW_EXIF_ASCII,                 # Speed unit #p55
 237                                 'GPSSpeed' => MW_EXIF_RATIONAL,                 # Speed of GPS receiver
 238                                 'GPSTrackRef' => MW_EXIF_ASCII,                 # Reference for direction of movement #p55
 239                                 'GPSTrack' => MW_EXIF_RATIONAL,                 # Direction of movement
 240                                 'GPSImgDirectionRef' => MW_EXIF_ASCII,          # Reference for direction of image #p56
 241                                 'GPSImgDirection' => MW_EXIF_RATIONAL,          # Direction of image
 242                                 'GPSMapDatum' => MW_EXIF_ASCII,                 # Geodetic survey data used
 243                                 'GPSDestLatitudeRef' => MW_EXIF_ASCII,          # Reference for latitude of destination #p56
 244                                 'GPSDestLatitude' => MW_EXIF_RATIONAL,          # Latitude destination
 245                                 'GPSDestLongitudeRef' => MW_EXIF_ASCII,         # Reference for longitude of destination #p57
 246                                 'GPSDestLongitude' => MW_EXIF_RATIONAL,         # Longitude of destination
 247                                 'GPSDestBearingRef' => MW_EXIF_ASCII,           # Reference for bearing of destination #p57
 248                                 'GPSDestBearing' => MW_EXIF_RATIONAL,           # Bearing of destination
 249                                 'GPSDestDistanceRef' => MW_EXIF_ASCII,          # Reference for distance to destination #p57-58
 250                                 'GPSDestDistance' => MW_EXIF_RATIONAL,          # Distance to destination
 251                                 'GPSProcessingMethod' => MW_EXIF_UNDEFINED,     # Name of GPS processing method
 252                                 'GPSAreaInformation' => MW_EXIF_UNDEFINED,      # Name of GPS area
 253                                 'GPSDateStamp' => MW_EXIF_ASCII,                # GPS date
 254                                 'GPSDifferential' => MW_EXIF_SHORT,             # GPS differential correction
 255                         ),
 256                 );
 257
 258                 $this->makeFlatExifTags();
 259         }
 260
 261         /**
 262          * Generate a flat list of the exif tags
 263          */
 264         function makeFlatExifTags() {
 265                 $this->extractTags( $this->mExif );
 266         }
 267
 268         /**
 269          * A recursing extractor function used by makeFlatExifTags()
 270          *
 271          * Note: This used to use an array_walk function, but it made PHP5
 272          * segfault, see `cvs diff -u -r 1.4 -r 1.5 Exif.php`
 273          */
 274         function extractTags( $tagset ) {
 275                 foreach( $tagset as $key => $val ) {
 276                         if( is_array( $val ) ) {
 277                                 $this->extractTags( $val );
 278                         } else {
 279                                 $this->mFlatExif[$key] = $val;
 280                         }
 281                 }
 282         }
 283
 284          /**
 285           * The version of the output format
 286           *
 287           * Before the actual metadata information is saved in the database we
 288           * strip some of it since we don't want to save things like thumbnails
 289           * which usually accompany Exif data. This value gets saved in the
 290           * database along with the actual Exif data, and if the version in the
 291           * database doesn't equal the value returned by this function the Exif
 292           * data is regenerated.
 293           *
 294           * @return int
 295           */
 296         function version() {
 297                 return 1; // We don't need no bloddy constants!
 298         }
 299
 300         /**#@+
 301          * Validates if a tag value is of the type it should be according to the Exif spec
 302          *
 303          * @param mixed $in The input value to check
 304          * @return bool
 305          */
 306         function isByte( $in ) {
 307                 $fname = 'isByte';
 308                 if ( is_numeric( $in ) && $in >= 0 && $in <= 255 ) {
 309                         wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 310                         return true;
 311                 } else {
 312                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 313                         return false;
 314                 }
 315         }
 316
 317         function isASCII( $in ) {
 318                 wfDebug("Exif::isASCII: input was '$in'\n");
 319                 return true; // TODO: FIXME
 320         }
 321
 322         function isShort( $in ) {
 323                 $fname = 'isShort';
 324                 if ( is_numeric( $in ) && $in >= 0 && $in <= 65536 ) {
 325                         wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 326                         return true;
 327                 } else {
 328                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 329                         return false;
 330                 }
 331         }
 332
 333         function isLong( $in ) {
 334                 $fname = 'isLong';
 335                 if ( is_numeric( $in ) && $in >= 0 && $in <= 4294967296 ) {
 336                         wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 337                         return true;
 338                 } else {
 339                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 340                         return false;
 341                 }
 342         }
 343
 344         function isRational( $in ) {
 345                 $fname = 'isRational';
 346                 $a = explode( '/', $in, 2 );
 347                 if ( $this->isLong( $a[0] ) && $this->isLong( $a[1] ) ) {
 348                         wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 349                         return true;
 350                 } else {
 351                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 352                         return false;
 353                 }
 354         }
 355
 356         /**
 357          * In order not to output binary gibberish such as raw thumbnails we
 358          * return false here
 359          *
 360          * @todo We might actually want to display some of the UNDEFINED
 361          *       stuff, but we strip it for now.
 362          */
 363         function isUndefined( $in ) {
 364                 $fname = 'isUndefined';
 365                 wfDebug("Exif::$fname: input was '$in'\n");
 366                 return false;
 367         }
 368
 369         function isSlong( $in ) {
 370                 $fname = 'isSlong';
 371                 if ( $this->isLong( abs( $in ) ) ) {
 372                         wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 373                         return true;
 374                 } else {
 375                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 376                         return false;
 377                 }
 378         }
 379
 380         function isSrational( $in ) {
 381                 $fname = 'isSrational';
 382                 $a = explode( '/', $in, 2 );
 383                 if ( $this->isSlong( $a[0] ) && $this->isSlong( $a[1] ) ) {
 384                          wfDebug("Exif::$fname: accepted: '$in' (type: " . gettype( $in ) . ")\n");
 385                          return true;
 386                 } else {
 387                         wfDebug("Exif::$fname: rejected: '$in' (type: " . gettype( $in ) . ")\n");
 388                         return false;
 389                 }
 390         }
 391         /**#@-*/
 392
 393         /**
 394          * Validates if a tag has a legal value according to the Exif spec
 395          *
 396          * @param string $tag The tag to check
 397          * @param mixed  $val The value of the tag
 398          * @return bool
 399          */
 400         function validate( $tag, $val ) {
 401                 // Fucks up if not typecast
 402                 switch( (string)$this->mFlatExif[$tag] ) {
 403                         case (string)MW_EXIF_BYTE:
 404                                 return $this->isByte( $val );
 405                         case (string)MW_EXIF_ASCII:
 406                                 return $this->isASCII( $val );
 407                         case (string)MW_EXIF_SHORT:
 408                                 return $this->isShort( $val );
 409                         case (string)MW_EXIF_LONG:
 410                                 return $this->isLong( $val );
 411                         case (string)MW_EXIF_RATIONAL:
 412                                 return $this->isRational( $val );
 413                         case (string)MW_EXIF_UNDEFINED:
 414                                 return $this->isUndefined( $val );
 415                         case (string)MW_EXIF_SLONG:
 416                                 return $this->isSlong( $val );
 417                         case (string)MW_EXIF_SRATIONAL:
 418                                 return $this->isSrational( $val );
 419                         case (string)MW_EXIF_SHORT.','.MW_EXIF_LONG:
 420                                 return $this->isShort( $val ) || $this->isLong( $val );
 421                         default:
 422                                 wfDebug( "Exif::validate: The tag \"$tag\" had an invalid value: \"$val\"\n" );
 423                                 return false;
 424                 }
 425         }
 426
 427         /**
 428          * Numbers given by Exif user agents are often magical, that is they
 429          * should be replaced by a detailed explanation depending on their
 430          * value which most of the time are plain integers. This function
 431          * formats Exif values into human readable form.
 432          *
 433          * @param string $tag The tag to be formatted
 434          * @param mixed  $val The value of the tag
 435          * @return string
 436          */
 437         function format( $tag, $val ) {
 438                 global $wgLang;
 439
 440                 switch( $tag ) {
 441                 case 'Compression':
 442                         switch( $val ) {
 443                         case 1: case 6:
 444                                 return $this->msg( $tag, $val );
 445                         }
 446                         break;
 447
 448                 case 'PhotometricInterpretation':
 449                         switch( $val ) {
 450                         case 2: case 6:
 451                                 return $this->msg( $tag, $val );
 452                         }
 453                         break;
 454
 455                 case 'Orientation':
 456                         switch( $val ) {
 457                         case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8:
 458                                 return $this->msg( $tag, $val );
 459                         }
 460                         break;
 461
 462                 case 'PlanarConfiguration':
 463                         switch( $val ) {
 464                         case 1: case 2:
 465                                 return $this->msg( $tag, $val );
 466                         }
 467                         break;
 468
 469                 // TODO: YCbCrSubSampling
 470                 // TODO: YCbCrPositioning
 471                 // TODO: If this field does not exists use 2
 472                 case 'ResolutionUnit': #p26
 473                         switch( $val ) {
 474                         case 2: case 3:
 475                                 return $this->msg( $tag, $val );
 476                         }
 477                         break;
 478
 479                 // TODO: YCbCrCoefficients  #p27 (see annex E)
 480                 case 'ExifVersion': case 'FlashpixVersion':
 481                         return "$val"/100;
 482
 483                 case 'ColorSpace':
 484                         switch( $val ) {
 485                         case 1: case 'FFFF.H':
 486                                 return $this->msg( $tag, $val );
 487                         }
 488                         break;
 489
 490                 case 'ComponentsConfiguration':
 491                         switch( $val ) {
 492                         case 0: case 1: case 2: case 3: case 4: case 5: case 6:
 493                                 return $this->msg( $tag, $val );
 494                         }
 495                         break;
 496
 497                 case 'DateTime':
 498                 case 'DateTimeOriginal':
 499                 case 'DateTimeDigitized':
 500                         return $wgLang->timeanddate( wfTimestamp(TS_MW, $val) );
 501
 502                 case 'ExposureProgram':
 503                         switch( $val ) {
 504                         case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8:
 505                                 return $this->msg( $tag, $val );
 506                         }
 507                         break;
 508
 509                 case 'MeteringMode':
 510                         switch( $val ) {
 511                         case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 255:
 512                                 return $this->msg( $tag, $val );
 513                         }
 514                         break;
 515
 516                 case 'LightSource':
 517                         switch( $val ) {
 518                         case 0: case 1: case 2: case 3: case 4: case 9: case 10: case 11:
 519                         case 12: case 13: case 14: case 15: case 17: case 18: case 19: case 20:
 520                         case 21: case 22: case 23: case 24: case 255:
 521                                 return $this->msg( $tag, $val );
 522                         }
 523                         break;
 524
 525                 // TODO: Flash
 526                 case 'SensingMethod':
 527                         switch( $val ) {
 528                         case 1: case 2: case 3: case 4: case 5: case 7: case 8:
 529                                 return $this->msg( $tag, $val );
 530                         }
 531                         break;
 532
 533                 case 'FileSource':
 534                         switch( $val ) {
 535                         case 3:
 536                                 return $this->msg( $tag, $val );
 537                         }
 538                         break;
 539
 540                 case 'SceneType':
 541                         switch( $val ) {
 542                         case 1:
 543                                 return $this->msg( $tag, $val );
 544                         }
 545                         break;
 546
 547                 case 'CustomRendered':
 548                         switch( $val ) {
 549                         case 0: case 1:
 550                                 return $this->msg( $tag, $val );
 551                         }
 552                         break;
 553
 554                 case 'ExposureMode':
 555                         switch( $val ) {
 556                         case 0: case 1: case 2:
 557                                 return $this->msg( $tag, $val );
 558                         }
 559                         break;
 560
 561                 case 'WhiteBalance':
 562                         switch( $val ) {
 563                         case 0: case 1:
 564                                 return $this->msg( $tag, $val );
 565                         }
 566                         break;
 567
 568                 case 'SceneCaptureType':
 569                         switch( $val ) {
 570                         case 0: case 1: case 2: case 3:
 571                                 return $this->msg( $tag, $val );
 572                         }
 573                         break;
 574
 575                 case 'GainControl':
 576                         switch( $val ) {
 577                         case 0: case 1: case 2: case 3: case 4:
 578                                 return $this->msg( $tag, $val );
 579                         }
 580                         break;
 581
 582                 case 'Contrast':
 583                         switch( $val ) {
 584                         case 0: case 1: case 2:
 585                                 return $this->msg( $tag, $val );
 586                         }
 587                         break;
 588
 589                 case 'Saturation':
 590                         switch( $val ) {
 591                         case 0: case 1: case 2:
 592                                 return $this->msg( $tag, $val );
 593                         }
 594                         break;
 595
 596                 case 'Sharpness':
 597                         switch( $val ) {
 598                         case 0: case 1: case 2:
 599                                 return $this->msg( $tag, $val );
 600                         }
 601                         break;
 602
 603                 case 'SubjectDistanceRange':
 604                         switch( $val ) {
 605                         case 0: case 1: case 2: case 3:
 606                                 return $this->msg( $tag, $val );
 607                         }
 608                         break;
 609
 610                 case 'GPSLatitudeRef':
 611                         switch( $val ) {
 612                         case 'N': case 'S':
 613                                 return $this->msg( $tag, $val );
 614                         }
 615                         break;
 616
 617                 case 'GPSLongitudeRef':
 618                         switch( $val ) {
 619                         case 'E': case 'W':
 620                                 return $this->msg( $tag, $val );
 621                         }
 622                         break;
 623
 624                 case 'GPSStatus':
 625                         switch( $val ) {
 626                         case 'A': case 'V':
 627                                 return $this->msg( $tag, $val );
 628                         }
 629                         break;
 630
 631                 case 'GPSMeasureMode':
 632                         switch( $val ) {
 633                         case 2: case 3:
 634                                 return $this->msg( $tag, $val );
 635                         }
 636                         break;
 637
 638                 case 'GPSSpeedRef':
 639                         switch( $val ) {
 640                         case 'K': case 'M': case 'N':
 641                                 return $this->msg( $tag, $val );
 642                         }
 643                         break;
 644
 645                 case 'GPSTrackRef':
 646                         switch( $val ) {
 647                         case 'T': case 'M':
 648                                 return $this->msg( $tag, $val );
 649                         }
 650                         break;
 651
 652                 case 'GPSImgDirectionRef':
 653                         switch( $val ) {
 654                         case 'T': case 'M':
 655                                 return $this->msg( $tag, $val );
 656                         }
 657                         break;
 658
 659                 case 'GPSDestLatitudeRef':
 660                         switch( $val ) {
 661                         case 'N': case 'S':
 662                                 return $this->msg( $tag, $val );
 663                         }
 664                         break;
 665
 666                 case 'GPSDestLongitudeRef':
 667                         switch( $val ) {
 668                         case 'E': case 'W':
 669                                 return $this->msg( $tag, $val );
 670                         }
 671                         break;
 672
 673                 case 'GPSDestBearingRef':
 674                         switch( $val ) {
 675                         case 'T': case 'M':
 676                                 return $this->msg( $tag, $val );
 677                         }
 678                         break;
 679                 case 'GPSDateStamp':
 680                         return $wgLang->date( substr( $val, 0, 4 ) . substr( $val, 5, 2 ) . substr( $val, 8, 2 ) . '000000' );
 681
 682                 // This is not in the Exif standard, just a special
 683                 // case for our purposes which enables wikis to wikify
 684                 // the make, model and software name to link to their articles.
 685                 case 'Make':
 686                 case 'Model':
 687                 case 'Software':
 688                         return wfMsg( strtolower( "exif-$tag-value" ), $val );
 689                 default:
 690                         return $val;
 691                 }
 692         }
 693
 694         /**
 695          * Conviniance function for format()
 696          *
 697          * @param string $tag The tag name to pass on
 698          * @param string $val The value of the tag
 699          * @return string A wfMsg of "exif-$tag-$val" in lower case
 700          */
 701         function msg( $tag, $val ) {
 702                 return wfMsg( strtolower("exif-$tag-$val") );
 703         }
 704 }
 705
 706 } // MEDIAWIKI