IllQ2SanQ.pl
From Bioinformatics Core Wiki
#!/usr/bin/perl -w
# AUTHOR: Joseph Fass
# LAST REVISED: August 2009
#
# The Bioinformatics Core at UC Davis Genome Center
# http://bioinformatics.ucdavis.edu
# Copyright (c) 2009 The Regents of University of California, Davis Campus.
# All rights reserved.
# IllQ2SanQ.pl converts Illumina (>= 1.3 pipeline) fastq format to Sanger fastq format
while (<>) {
$head1 = $_;
$seq = <>;
$head2 = <>;
$qual = <>;
print $head1.$seq.$head2;
chomp $qual;
@Q = split(//,$qual);
for ($i=0; $i<=$#Q; $i++) {
print chr( ord($Q[$i]) - 31 );
}
print "\n";
}