start a jpeg dump tool
Tony Cook
5 years ago
| 0 | #!perl | |
| 1 | use strict; | |
| 2 | use Getopt::Long; | |
| 3 | ||
| 4 | my $dumpall = 0; | |
| 5 | my $exiffile; | |
| 6 | GetOptions(dumpall => \$dumpall, | |
| 7 | "e|exif=s" => \$exiffile); | |
| 8 | ||
| 9 | my $file = shift | |
| 10 | or die "Usage: $0 filename\n"; | |
| 11 | ||
| 12 | open my $fh, "<", $file | |
| 13 | or die "$0: cannot open '$file': $!\n"; | |
| 14 | ||
| 15 | binmode $fh; | |
| 16 | ||
| 17 | ||
| 18 | while (!eof($fh)) { | |
| 19 | my $chead; | |
| 20 | unless (read($fh, $chead, 2) == 2) { | |
| 21 | eof $fh or die "Failed to read start of chunk: $!"; | |
| 22 | last; | |
| 23 | } | |
| 24 | if ($chead eq "\xFF\xD8") { | |
| 25 | print "Start of image\n"; | |
| 26 | } | |
| 27 | elsif ($chead =~ /^\xFF[\xE0-\xEF]$/) { | |
| 28 | # APP0-APP15 | |
| 29 | my $clen; | |
| 30 | unless (read($fh, $clen, 2) == 2) { | |
| 31 | die "Couldn't read length for APPn\n"; | |
| 32 | } | |
| 33 | my $len = unpack("S>", $clen); | |
| 34 | my $appdata; | |
| 35 | unless (read($fh, $appdata, $len-2) == $len-2) { | |
| 36 | print "length ", length $appdata, " expected $len\n"; | |
| 37 | die "Couldn't read application data for APPn\n"; | |
| 38 | } | |
| 39 | if ($chead eq "\xFF\xE0") { | |
| 40 | # APP0 | |
| 41 | my $type = substr($appdata, 0, 5, ''); | |
| 42 | print "APP0 ", $type =~ tr/\0//dr, "\n"; | |
| 43 | if ($type eq "JFIF\0") { | |
| 44 | my ($version, $units, $xdens, $ydens, $tx, $ty, $rest) = | |
| 45 | unpack("S>CS>S>CCa*", $appdata); | |
| 46 | printf " Version: %x\n", $version; | |
| 47 | print " Units: $units\n"; | |
| 48 | print " Density: $xdens x $ydens\n"; | |
| 49 | print " Thumbnail: $tx x $ty\n"; | |
| 50 | } | |
| 51 | else { | |
| 52 | # more to do | |
| 53 | } | |
| 54 | } | |
| 55 | elsif ($chead eq "\xFF\xE1") { | |
| 56 | # APP1 | |
| 57 | if ($appdata =~ s/^Exif\0.//) { | |
| 58 | print " EXIF data\n"; | |
| 59 | if ($exiffile) { | |
| 60 | open my $eh, ">", $exiffile | |
| 61 | or die "Cannot create $exiffile: $!\n"; | |
| 62 | binmode $eh; | |
| 63 | print $eh $appdata; | |
| 64 | close $eh | |
| 65 | or die "Cannot close $exiffile: $!\n"; | |
| 66 | } | |
| 67 | } | |
| 68 | } | |
| 69 | } | |
| 70 | else { | |
| 71 | die "I don't know how to handle ", unpack("H*", $chead), "\n"; | |
| 72 | } | |
| 73 | } | |
| 74 | ||
| 75 | =head HEAD | |
| 76 | ||
| 77 | jpegdump.pl - dump the structure of a JPEG image file. | |
| 78 | ||
| 79 | =head1 SYNOPSIS | |
| 80 | ||
| 81 | perl jpegdump.pl [-dumpall] [-exif=exifdata] filename | |
| 82 | ||
| 83 | =head1 DESCRIPTION | |
| 84 | ||
| 85 | Dumps the structure of a JPEG image file. | |
| 86 | ||
| 87 | Options: | |
| 88 | ||
| 89 | =over | |
| 90 | ||
| 91 | =item * | |
| 92 | ||
| 93 | C<-dumpall> - dump the entire contents of each chunk rather than just | |
| 94 | the leading bytes. Currently unimplemented. | |
| 95 | ||
| 96 | =item * | |
| 97 | ||
| 98 | C<< -exif I<filename> >> - extract the EXIF blob to a file. | |
| 99 | ||
| 100 | =back | |
| 101 | ||
| 102 | This is incomplete, I mostly wrote it to extract the EXIF blob, but I | |
| 103 | expect I'll finish it at some point. | |
| 104 | ||
| 105 | =cut |