From: decoder [mailto:[EMAIL PROTECTED]
> Hello all,
>
>
> since 3.5.0 RC1 was released, we fixed many bugs, thanks to the many
> testers and bug reporters :) so big thanks.
Excellent work. Thank you for your efforts in bringing it to us.
Anyway, I'm wondering why the image hashing is made that way, leading to:
1) a variable-length key and
2) possibly even a very long one (depending on focr_hash_max).
This pretty inefficient to handle on SQL backends and, infact, FuzzyOcr.mysql
must define the "key" columns as varchar(255)...
I see that the "problem" is due to the way the hashing is calculate in
FuzzyOcr/Hashing.pm:
<code-snip>
my $cnt = 0;
my $c = scalar(@stdout_data);
my $s = (stat($pfile))[7] || 0;
$hash = sprintf "%d:%d:%d:%d",$s,
defined $pic->{height} ? $pic->{height} : 0,
defined $pic->{width} ? $pic->{width} : 0,
$c;
if ($Threshold{max_hash}) {
foreach (@stdout_data) {
$_ =~ s/ +/ /g;
my(@d) = split(' ', $_);
$hash .= sprintf("::%d:%d:%d:%d:%d",@d);
if ($cnt++ ge $Threshold{max_hash}) {
last;
}
}
}
</code-snip>
Why not use some form of digest? In example, something like this could be more
interesting to me:
<code-snip>
my $cnt = 0;
my $c = scalar(@stdout_data);
my $s = (stat($pfile))[7] || 0;
$hash = sprintf "%d:%d:%d:%d",$s,
defined $pic->{height} ? $pic->{height} : 0,
defined $pic->{width} ? $pic->{width} : 0,
$c;
if ($Threshold{max_hash}) {
use Digest;
my $hctx = Digest->new('MD5');
my $clrcnt = 0;
foreach (@stdout_data) {
my(@d) = split(/ +/, $_);
$hctx->add(pack('CCCN', $d[0], $d[1], $d[2], $d[4]));
if (++$clrcnt >= $Threshold{max_hash}) {
last;
}
}
$hctx->add(pack('N', $clrcnt));
$hash .= '::' . $hctx->hexdigest;
}
</code-snip>
Which basicly creates a digest on the first (most frequent)
$Threshold{max_hash} palette colors instead of simply enumerating them. The
output will be around 40-45 characters and will stick with this length
irregardless of the value of the focr_hash_max setting.
Please note I'm not a perl wizard no a SA developer, so there is space for
optimizations here. In example, Digest->new('MD5') could probably even be
globally definited and there initialized, and a $hctx->reset issued when a new
digest have to be computed.
What are your thoughts about?
Regards,
giampaolo
