[34921] | 1 | #------------------------------------------------------------------------------
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| 2 | # File: FITS.pm
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| 3 | #
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| 4 | # Description: Read Flexible Image Transport System metadata
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| 5 | #
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| 6 | # Revisions: 2018/03/07 - P. Harvey Created
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| 7 | #
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| 8 | # References: 1) https://fits.gsfc.nasa.gov/fits_standard.html
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| 9 | #------------------------------------------------------------------------------
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| 10 |
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| 11 | package Image::ExifTool::FITS;
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| 12 |
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| 13 | use strict;
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| 14 | use vars qw($VERSION);
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| 15 | use Image::ExifTool qw(:DataAccess :Utils);
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| 16 |
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| 17 | $VERSION = '1.01';
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| 18 |
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| 19 | # FITS tags (ref 1)
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| 20 | %Image::ExifTool::FITS::Main = (
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| 21 | GROUPS => { 2 => 'Image' },
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| 22 | NOTES => q{
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| 23 | This table lists some standard Flexible Image Transport System (FITS) tags,
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| 24 | but ExifTool will extract any other tags found. See
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| 25 | L<https://fits.gsfc.nasa.gov/fits_standard.html> for the specification.
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| 26 | },
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| 27 | TELESCOP => 'Telescope',
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| 28 | BACKGRND => 'Background',
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| 29 | INSTRUME => 'Instrument',
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| 30 | OBJECT => 'Object',
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| 31 | OBSERVER => 'Observer',
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| 32 | DATE => { Name => 'CreateDate', Groups => { 2 => 'Time' } },
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| 33 | AUTHOR => { Name => 'Author', Groups => { 2 => 'Author' } },
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| 34 | REFERENC => 'Reference',
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| 35 | 'DATE-OBS'=> { Name => 'ObservationDate', Groups => { 2 => 'Time' } },
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| 36 | 'TIME-OBS'=> { Name => 'ObservationTime', Groups => { 2 => 'Time' } },
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| 37 | 'DATE-END'=> { Name => 'ObservationDateEnd', Groups => { 2 => 'Time' } },
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| 38 | 'TIME-END'=> { Name => 'ObservationTimeEnd', Groups => { 2 => 'Time' } },
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| 39 | COMMENT => 'Comment',
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| 40 | HISTORY => 'History',
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| 41 | );
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| 42 |
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| 43 | #------------------------------------------------------------------------------
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| 44 | # Read information in a FITS document
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| 45 | # Inputs: 0) ExifTool ref, 1) dirInfo ref
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| 46 | # Returns: 1 on success, 0 if this wasn't a valid FITS file
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| 47 | sub ProcessFITS($$)
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| 48 | {
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| 49 | my ($et, $dirInfo) = @_;
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| 50 | my $raf = $$dirInfo{RAF};
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| 51 | my ($buff, $tag, $continue);
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| 52 |
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| 53 | return 0 unless $raf->Read($buff, 80) == 80 and $buff =~ /^SIMPLE = {20}T/;
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| 54 | $et->SetFileType();
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| 55 | my $tagTablePtr = GetTagTable('Image::ExifTool::FITS::Main');
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| 56 |
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| 57 | for (;;) {
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| 58 | $raf->Read($buff, 80) == 80 or $et->Warn('Truncated FITS header'), last;
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| 59 | my $key = substr($buff, 0, 8);
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| 60 | $key =~ s/ +$//; # remove trailing space from key
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| 61 | if ($key eq 'CONTINUE') {
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| 62 | defined $continue or $et->WarnOnce('Unexpected FITS CONTINUE keyword'), next;
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| 63 | } else {
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| 64 | if (defined $continue) {
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| 65 | # the previous value wasn't continued, so store with the trailing '&'
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| 66 | $et->HandleTag($tagTablePtr, $tag, $continue . '&');
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| 67 | undef $continue;
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| 68 | }
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| 69 | last if $key eq 'END';
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| 70 | # make sure the key is valid
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| 71 | $key =~ /^[-_A-Z0-9]*$/ or $et->Warn('Format error in FITS header'), last;
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| 72 | # ignore lines other than tags, COMMENT or HISTORY
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| 73 | next unless substr($buff,8,2) eq '= ' or $key eq 'COMMENT' or $key eq 'HISTORY';
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| 74 | # save tag name (avoiding potential conflict with ExifTool variables)
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| 75 | $tag = $Image::ExifTool::specialTags{$key} ? "_$key" : $key;
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| 76 | # add to tag table if necessary
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| 77 | unless ($$tagTablePtr{$tag}) {
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| 78 | my $name = ucfirst lc $tag; # make tag name lower case with leading capital
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| 79 | $name =~ s/_(.)/\U$1/g; # remove all '_' and capitalize subsequent letter
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| 80 | AddTagToTable($tagTablePtr, $tag, { Name => $name });
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| 81 | }
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| 82 | }
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| 83 | my $val = substr($buff, 10);
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| 84 | # parse quoted values
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| 85 | if ($val =~ /^'(.*?)'(.*)/) {
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| 86 | ($val, $buff) = ($1, $2);
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| 87 | while ($buff =~ /^('.*?)'(.*)/) { # handle escaped quotes
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| 88 | $val .= $1;
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| 89 | $buff = $2;
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| 90 | }
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| 91 | $val =~ s/ +$//; # remove trailing spaces
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| 92 | if (defined $continue) {
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| 93 | $val = $continue . $val;
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| 94 | undef $continue;
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| 95 | }
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| 96 | # check for possible continuation, removing trailing '&'
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| 97 | $val =~ s/\&$// and $continue = $val, next;
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| 98 | } elsif (defined $continue) {
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| 99 | $et->WarnOnce('Invalid FITS CONTINUE value');
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| 100 | next;
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| 101 | } else {
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| 102 | $val =~ s/ *(\/.*)?$//; # remove trailing spaces and comment
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| 103 | next unless length $val; # ignore undefined values
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| 104 | $val =~ s/^ +//; # remove leading spaces
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| 105 | # re-format floating-point values to use 'e'
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| 106 | $val =~ tr/DE/e/ if $val =~ /^[+-]?(?=\d|\.\d)\d*(\.\d*)?([ED]([+-]?\d+))?$/;
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| 107 | }
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| 108 | $et->HandleTag($tagTablePtr, $tag, $val);
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| 109 | }
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| 110 | return 1;
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| 111 | }
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| 112 |
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| 113 | 1; # end
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| 114 |
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| 115 | __END__
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| 116 |
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| 117 | =head1 NAME
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| 118 |
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| 119 | Image::ExifTool::FITS - Read Flexible Image Transport System metadata
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| 120 |
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| 121 | =head1 SYNOPSIS
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| 122 |
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| 123 | This module is used by Image::ExifTool
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| 124 |
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| 125 | =head1 DESCRIPTION
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| 126 |
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| 127 | This module contains definitions required by Image::ExifTool to read meta
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| 128 | information from FITS (Flexible Image Transport System) images.
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| 129 |
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| 130 | =head1 AUTHOR
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| 131 |
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| 132 | Copyright 2003-2021, Phil Harvey (philharvey66 at gmail.com)
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| 133 |
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| 134 | This library is free software; you can redistribute it and/or modify it
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| 135 | under the same terms as Perl itself.
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| 136 |
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| 137 | =head1 REFERENCES
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| 138 |
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| 139 | =over 4
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| 140 |
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| 141 | =item L<https://fits.gsfc.nasa.gov/fits_standard.html>
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| 142 |
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| 143 | =back
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| 144 |
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| 145 | =head1 SEE ALSO
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| 146 |
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| 147 | L<Image::ExifTool::TagNames/FITS Tags>,
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| 148 | L<Image::ExifTool(3pm)|Image::ExifTool>
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| 149 |
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| 150 | =cut
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| 151 |
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