/libjpeg.php
PHP | 277 lines | 234 code | 11 blank | 32 comment | 49 complexity | 3056f504940ba762be744ded8d3fc469 MD5 | raw file
Possible License(s): GPL-2.0
- <?php
- function get_jpeg_header_data( &$buff, $buff_len, $want=null ) {
- $data = buffer_read( $buff, $buff_len, 2, true ); // Read the first two characters
- // Check that the first two characters are 0xFF 0xDA (SOI - Start of image)
- if ( $data != "\xFF\xD8" ) {
- // No SOI (FF D8) at start of file - This probably isn't a JPEG file - close file and return;
- return false;
- }
- $data = buffer_read( $buff, $buff_len, 2 ); // Read the third character
- // Check that the third character is 0xFF (Start of first segment header)
- if ( $data{0} != "\xFF" ) {
- // NO FF found - close file and return - JPEG is probably corrupted
- return false;
- }
- // Cycle through the file until, one of:
- // 1) an EOI (End of image) marker is hit,
- // 2) we have hit the compressed image data (no more headers are allowed after data)
- // 3) or end of file is hit
- $headerdata = array();
- $hit_compressed_image_data = FALSE;
- while ( ( $data{1} != "\xD9" ) && ( !$hit_compressed_image_data) && ( $data != '' ) ) {
- // Found a segment to look at.
- // Check that the segment marker is not a Restart marker - restart markers don't have size or data after them
- if ( ( ord($data{1}) < 0xD0 ) || ( ord($data{1}) > 0xD7 ) ) {
- // Segment isn't a Restart marker
- $sizestr = buffer_read( $buff, $buff_len, 2 ); // Read the next two bytes (size)
- if ( null === $sizestr )
- break;
- $decodedsize = unpack ("nsize", $sizestr); // convert the size bytes to an integer
- // Read the segment data with length indicated by the previously read size
- $segdata = buffer_read( $buff, $buff_len, $decodedsize['size'] - 2 );
- // Store the segment information in the output array
- if ( !$want || $want == ord($data{1}) ) {
- $headerdata[] = (object)array(
- "SegType" => ord($data{1}),
- "SegName" => $GLOBALS[ "JPEG_Segment_Names" ][ ord($data{1}) ],
- "SegDesc" => $GLOBALS[ "JPEG_Segment_Descriptions" ][ ord($data{1}) ],
- "SegData" => $segdata
- );
- }
- }
- // If this is a SOS (Start Of Scan) segment, then there is no more header data - the compressed image data follows
- if ( $data{1} == "\xDA" ) {
- $hit_compressed_image_data = true;
- } else {
- // Not an SOS - Read the next two bytes - should be the segment marker for the next segment
- $data = buffer_read( $buff, $buff_len, 2 );
- // Check that the first byte of the two is 0xFF as it should be for a marker
- if ( $data{0} != "\xFF" ) {
- // NO FF found - close file and return - JPEG is probably corrupted
- return false;
- }
- }
- }
- return $headerdata;
- }
- function buffer_read( &$buff, $buff_len, $len, $new=false ) {
- static $pointer = 0;
- if ( $new )
- $pointer = 0;
- if ( $pointer + $len > $buff_len ) {
- $len = $buff_len - $pointer;
- if ( $len < 1 )
- return null;
- }
- // substr() is slower and doubles the peak memory usage
- $data = '';
- while ( $len-- )
- $data .= $buff[$pointer++];
- return $data;
- }
- // The names of the JPEG segment markers, indexed by their marker number
- $GLOBALS[ "JPEG_Segment_Names" ] = array(
- 0xC0 => "SOF0", 0xC1 => "SOF1", 0xC2 => "SOF2", 0xC3 => "SOF3",
- 0xC5 => "SOF5", 0xC6 => "SOF6", 0xC7 => "SOF7", 0xC8 => "JPG",
- 0xC9 => "SOF9", 0xCA => "SOF10", 0xCB => "SOF11", 0xCD => "SOF13",
- 0xCE => "SOF14", 0xCF => "SOF15",
- 0xC4 => "DHT", 0xCC => "DAC",
- 0xD0 => "RST0", 0xD1 => "RST1", 0xD2 => "RST2", 0xD3 => "RST3",
- 0xD4 => "RST4", 0xD5 => "RST5", 0xD6 => "RST6", 0xD7 => "RST7",
- 0xD8 => "SOI", 0xD9 => "EOI", 0xDA => "SOS", 0xDB => "DQT",
- 0xDC => "DNL", 0xDD => "DRI", 0xDE => "DHP", 0xDF => "EXP",
- 0xE0 => "APP0", 0xE1 => "APP1", 0xE2 => "APP2", 0xE3 => "APP3",
- 0xE4 => "APP4", 0xE5 => "APP5", 0xE6 => "APP6", 0xE7 => "APP7",
- 0xE8 => "APP8", 0xE9 => "APP9", 0xEA => "APP10", 0xEB => "APP11",
- 0xEC => "APP12", 0xED => "APP13", 0xEE => "APP14", 0xEF => "APP15",
- 0xF0 => "JPG0", 0xF1 => "JPG1", 0xF2 => "JPG2", 0xF3 => "JPG3",
- 0xF4 => "JPG4", 0xF5 => "JPG5", 0xF6 => "JPG6", 0xF7 => "JPG7",
- 0xF8 => "JPG8", 0xF9 => "JPG9", 0xFA => "JPG10", 0xFB => "JPG11",
- 0xFC => "JPG12", 0xFD => "JPG13",
- 0xFE => "COM", 0x01 => "TEM", 0x02 => "RES",
- );
- // The descriptions of the JPEG segment markers, indexed by their marker number
- $GLOBALS[ "JPEG_Segment_Descriptions" ] = array(
- /* JIF Marker byte pairs in JPEG Interchange Format sequence */
- 0xC0 => "Start Of Frame (SOF) Huffman - Baseline DCT",
- 0xC1 => "Start Of Frame (SOF) Huffman - Extended sequential DCT",
- 0xC2 => "Start Of Frame Huffman - Progressive DCT (SOF2)",
- 0xC3 => "Start Of Frame Huffman - Spatial (sequential) lossless (SOF3)",
- 0xC5 => "Start Of Frame Huffman - Differential sequential DCT (SOF5)",
- 0xC6 => "Start Of Frame Huffman - Differential progressive DCT (SOF6)",
- 0xC7 => "Start Of Frame Huffman - Differential spatial (SOF7)",
- 0xC8 => "Start Of Frame Arithmetic - Reserved for JPEG extensions (JPG)",
- 0xC9 => "Start Of Frame Arithmetic - Extended sequential DCT (SOF9)",
- 0xCA => "Start Of Frame Arithmetic - Progressive DCT (SOF10)",
- 0xCB => "Start Of Frame Arithmetic - Spatial (sequential) lossless (SOF11)",
- 0xCD => "Start Of Frame Arithmetic - Differential sequential DCT (SOF13)",
- 0xCE => "Start Of Frame Arithmetic - Differential progressive DCT (SOF14)",
- 0xCF => "Start Of Frame Arithmetic - Differential spatial (SOF15)",
- 0xC4 => "Define Huffman Table(s) (DHT)",
- 0xCC => "Define Arithmetic coding conditioning(s) (DAC)",
- 0xD0 => "Restart with modulo 8 count 0 (RST0)",
- 0xD1 => "Restart with modulo 8 count 1 (RST1)",
- 0xD2 => "Restart with modulo 8 count 2 (RST2)",
- 0xD3 => "Restart with modulo 8 count 3 (RST3)",
- 0xD4 => "Restart with modulo 8 count 4 (RST4)",
- 0xD5 => "Restart with modulo 8 count 5 (RST5)",
- 0xD6 => "Restart with modulo 8 count 6 (RST6)",
- 0xD7 => "Restart with modulo 8 count 7 (RST7)",
- 0xD8 => "Start of Image (SOI)",
- 0xD9 => "End of Image (EOI)",
- 0xDA => "Start of Scan (SOS)",
- 0xDB => "Define quantization Table(s) (DQT)",
- 0xDC => "Define Number of Lines (DNL)",
- 0xDD => "Define Restart Interval (DRI)",
- 0xDE => "Define Hierarchical progression (DHP)",
- 0xDF => "Expand Reference Component(s) (EXP)",
- 0xE0 => "Application Field 0 (APP0) - usually JFIF or JFXX",
- 0xE1 => "Application Field 1 (APP1) - usually EXIF or XMP/RDF",
- 0xE2 => "Application Field 2 (APP2) - usually Flashpix",
- 0xE3 => "Application Field 3 (APP3)",
- 0xE4 => "Application Field 4 (APP4)",
- 0xE5 => "Application Field 5 (APP5)",
- 0xE6 => "Application Field 6 (APP6)",
- 0xE7 => "Application Field 7 (APP7)",
- 0xE8 => "Application Field 8 (APP8)",
- 0xE9 => "Application Field 9 (APP9)",
- 0xEA => "Application Field 10 (APP10)",
- 0xEB => "Application Field 11 (APP11)",
- 0xEC => "Application Field 12 (APP12) - usually [picture info]",
- 0xED => "Application Field 13 (APP13) - usually photoshop IRB / IPTC",
- 0xEE => "Application Field 14 (APP14)",
- 0xEF => "Application Field 15 (APP15)",
- 0xF0 => "Reserved for JPEG extensions (JPG0)",
- 0xF1 => "Reserved for JPEG extensions (JPG1)",
- 0xF2 => "Reserved for JPEG extensions (JPG2)",
- 0xF3 => "Reserved for JPEG extensions (JPG3)",
- 0xF4 => "Reserved for JPEG extensions (JPG4)",
- 0xF5 => "Reserved for JPEG extensions (JPG5)",
- 0xF6 => "Reserved for JPEG extensions (JPG6)",
- 0xF7 => "Reserved for JPEG extensions (JPG7)",
- 0xF8 => "Reserved for JPEG extensions (JPG8)",
- 0xF9 => "Reserved for JPEG extensions (JPG9)",
- 0xFA => "Reserved for JPEG extensions (JPG10)",
- 0xFB => "Reserved for JPEG extensions (JPG11)",
- 0xFC => "Reserved for JPEG extensions (JPG12)",
- 0xFD => "Reserved for JPEG extensions (JPG13)",
- 0xFE => "Comment (COM)",
- 0x01 => "For temp private use arith code (TEM)",
- 0x02 => "Reserved (RES)",
- );
- /**
- * Most of this function is taken directly from the source code for imagemagick
- * and how it handles identify -verbose $filename to present you with a Quality
- * number. This number should be considered approximate. It's essentially
- * based upon the numbers used to perform compression on the original image
- * data...
- *
- * See: http://www.obrador.com/essentialjpeg/headerinfo.htm
- * See: http://www.impulseadventure.com/photo/jpeg-quantization.html
- * See: http://www.impulseadventure.com/photo/jpeg-huffman-coding.html
- */
- function get_jpeg_quality( &$buff, $buff_len = null ) {
- $tables = array(
- 'multi' => array(
- 'hash' => array(
- 1020, 1015, 932, 848, 780, 735, 702, 679, 660, 645,
- 632, 623, 613, 607, 600, 594, 589, 585, 581, 571,
- 555, 542, 529, 514, 494, 474, 457, 439, 424, 410,
- 397, 386, 373, 364, 351, 341, 334, 324, 317, 309,
- 299, 294, 287, 279, 274, 267, 262, 257, 251, 247,
- 243, 237, 232, 227, 222, 217, 213, 207, 202, 198,
- 192, 188, 183, 177, 173, 168, 163, 157, 153, 148,
- 143, 139, 132, 128, 125, 119, 115, 108, 104, 99,
- 94, 90, 84, 79, 74, 70, 64, 59, 55, 49,
- 45, 40, 34, 30, 25, 20, 15, 11, 6, 4,
- 0
- ), // hash
- 'sums' => array (
- 32640, 32635, 32266, 31495, 30665, 29804, 29146, 28599, 28104,
- 27670, 27225, 26725, 26210, 25716, 25240, 24789, 24373, 23946,
- 23572, 22846, 21801, 20842, 19949, 19121, 18386, 17651, 16998,
- 16349, 15800, 15247, 14783, 14321, 13859, 13535, 13081, 12702,
- 12423, 12056, 11779, 11513, 11135, 10955, 10676, 10392, 10208,
- 9928, 9747, 9564, 9369, 9193, 9017, 8822, 8639, 8458,
- 8270, 8084, 7896, 7710, 7527, 7347, 7156, 6977, 6788,
- 6607, 6422, 6236, 6054, 5867, 5684, 5495, 5305, 5128,
- 4945, 4751, 4638, 4442, 4248, 4065, 3888, 3698, 3509,
- 3326, 3139, 2957, 2775, 2586, 2405, 2216, 2037, 1846,
- 1666, 1483, 1297, 1109, 927, 735, 554, 375, 201,
- 128, 0
- ), // sums
- ), // multi
- 'single' => array(
- 'hash' => array(
- 510, 505, 422, 380, 355, 338, 326, 318, 311, 305,
- 300, 297, 293, 291, 288, 286, 284, 283, 281, 280,
- 279, 278, 277, 273, 262, 251, 243, 233, 225, 218,
- 211, 205, 198, 193, 186, 181, 177, 172, 168, 164,
- 158, 156, 152, 148, 145, 142, 139, 136, 133, 131,
- 129, 126, 123, 120, 118, 115, 113, 110, 107, 105,
- 102, 100, 97, 94, 92, 89, 87, 83, 81, 79,
- 76, 74, 70, 68, 66, 63, 61, 57, 55, 52,
- 50, 48, 44, 42, 39, 37, 34, 31, 29, 26,
- 24, 21, 18, 16, 13, 11, 8, 6, 3, 2,
- 0
- ), // hash
- 'sums' => array(
- 16320, 16315, 15946, 15277, 14655, 14073, 13623, 13230, 12859,
- 12560, 12240, 11861, 11456, 11081, 10714, 10360, 10027, 9679,
- 9368, 9056, 8680, 8331, 7995, 7668, 7376, 7084, 6823,
- 6562, 6345, 6125, 5939, 5756, 5571, 5421, 5240, 5086,
- 4976, 4829, 4719, 4616, 4463, 4393, 4280, 4166, 4092,
- 3980, 3909, 3835, 3755, 3688, 3621, 3541, 3467, 3396,
- 3323, 3247, 3170, 3096, 3021, 2952, 2874, 2804, 2727,
- 2657, 2583, 2509, 2437, 2362, 2290, 2211, 2136, 2068,
- 1996, 1915, 1858, 1773, 1692, 1620, 1552, 1477, 1398,
- 1326, 1251, 1179, 1109, 1031, 961, 884, 814, 736,
- 667, 592, 518, 441, 369, 292, 221, 151, 86,
- 64, 0
- ), // sums
- ), // single
- ); // tables
-
- if ( ! isset( $buff_len ) )
- $buff_len = strlen( $buff );
- $headers = get_jpeg_header_data( $buff, $buff_len, 0xDB );
- if ( !is_array( $headers ) || !count( $headers ) )
- return 100;
- $header = $headers[0];
- $quality = 0;
- if ( strlen($header->SegData) > 128 ) {
- $entry = array( 0 => array(), 1 => array() );
- foreach ( str_split( substr( $header->SegData, 1, 64) ) as $chr )
- $entry[0][] = ord($chr);
- foreach ( str_split( substr( $header->SegData, -64) ) as $chr )
- $entry[1][] = ord($chr);
- $sum = array_sum( $entry[0] ) + array_sum( $entry[1] );
- $qvalue = $entry[0][2] + $entry[0][53] + $entry[1][0] + $entry[1][63];
- $table = "multi";
- } else if ( strlen($header->SegData) > 64 ) {
- $entry = array( 0 => array() );
- foreach ( str_split( substr( $header->SegData, 1, 64) ) as $chr )
- $entry[0][] = ord($chr);
- $sum = array_sum( $entry[0] );
- $qvalue = $entry[0][2] + $entry[0][53];
- $table = "single";
- } else {
- return 100; // go with a safe value
- }
- for( $i = 0; $i <= 100; $i++ ) {
- if ( ( $qvalue < $tables[$table]['hash'][$i] ) && ( $sum < $tables[$table]['sums'][$i] ) )
- continue;
- return $i;
- }
- return 100; // go with a safe value
- }