User talk:BytePilot: Difference between revisions

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(Replaced content with "hi - what settings did you use for the test cake image? i didn't get the chance to do any other other night as the laser was screwed - so that's so far the only test image we…")
 
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well I've done that, but the output is not what we want.
hi - what settings did you use for the test cake image? i didn't get the chance to do any other other night as the laser was screwed - so that's so far the only test image we have.  


http://hack.rs/cgi-bin/threshold_bitwise.pl
you think it needs less power?


<pre>
is the combined-layers file on the laser's pc?


#!/usr/bin/perl -w
--[[User:AndyE|AndyE]] 18:37, 16 January 2011 (UTC)
use strict;
use CGI;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
 
my $q = CGI->new();
 
print $q->header;
print $q->start_html;
 
print $q->p("this is a thing for doing threshholding");
print $q->p("<small>or possibly <i>thresholding</i>?</small>");
 
print $q->start_form( -enctype => "multipart/form-data" );
 
print $q->p("file");
print $q->filefield('uploaded_file');
print $q->submit();
 
print $q->end_form;
 
# do we have an upload?
my $filehandle = $q->upload('uploaded_file');
if (defined $filehandle) {
 
    # do shit
    print $q->p("I'm doing shit");
 
    # no, actually do shit
    my $filename = $q->param('uploaded_file');
    my $tempfile = $q->tmpFileName($filename);
 
    foreach my $i (0 .. 7) {
 
        my $n = 2 ** ($i + 8);
 
        my @ar = ("gm",
                  "convert", "-type", "grayscale", "-colors", 256, "-operator", "ALL AND $n", "-threshold", $n-1,
                  $tempfile,
                  "/var/www/threshold_output/$filename".$i );
 
        print $q->p("$i : $n : " . join " ", @ar);
 
        system(@ar) == 0 or carp "system call failed: $?"; #safer than passing a string to system()
 
        print $q->img({src => "/threshold_output/$filename".$i});
    }
}
 
 
print $q->end_html;
 
</pre>
 
I tried doing just the "-operator ALL AND $n" part by itself, it didn't seem to do anything...
 
--[[User:AndyE|AndyE]] 14:16, 12 January 2011 (UTC)
 
Possible sytax error ?
 
<pre>
                  "convert", "-type", "grayscale", "-colors", 256, "-operator", "ALL AND $n", "-threshold", $n-1,
</pre>
Should perhaps be
<pre>
                  "convert", "-type", "grayscale", "-colors", 256, "-operator", "ALL AND", $n, "-threshold", $n-1,
</pre>
?
 
<hr>
 
yes - seems to need to be "All", "And", "Whatever". Still, here's one that kinds does what we want...
 
http://hack.rs/cgi-bin/threshold_grayscale.pl
 
<pre>
 
#!/usr/bin/perl -w
use strict;
use CGI;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use List::Util qw(max min);
 
my $q = CGI->new();
 
print $q->header;
print $q->start_html;
 
print $q->p("this is a thing for doing threshholding");
print $q->p("<small>or possibly <i>thresholding</i>?</small>");
 
print $q->start_form( -enctype => "multipart/form-data" );
 
print $q->p("file");
print $q->filefield('uploaded_file');
print $q->submit();
 
print $q->end_form;
 
# do we have an upload?
my $filehandle = $q->upload('uploaded_file');
if (defined $filehandle) {
 
    # do shit
    print $q->p("I'm doing shit");
 
    # no, actually do shit
    my $filename = $q->param('uploaded_file');
    my $tempfile = $q->tmpFileName($filename);
 
    foreach my $i (0 .. 7) {
 
        my $n = ((2 ** (8 + $i)) / 2**16 )*100; #as a percentage
 
        my @ar = ("gm",
                  # "convert", "-type", "grayscale", "-colors", 8, "-threshold", 12.5*$i ."%",
                  "convert", "-type", "grayscale", "-operator",
                    "Gray", "And", $n  ."%",
                    "-threshold", max($n -1, 0) ."%",
                  $tempfile,
                  "/var/www/threshold_output/$filename".$i );
 
        print $q->p("$i : " . join " ", @ar);
 
        system(@ar) == 0 or carp "system call failed: $?"; #safer than passing a string to system()
 
        print $q->img({src => "/threshold_output/$filename".$i});
    }
}
 
 
print $q->end_html;
 
 
 
</pre>
 
i converted the raw values to percentages of a max because it wasn't working the other way. I'm not clear on the bit depth of the greyscale image. tried setting it with -depth but still no joy. still, this version is kind of working as it is.
 
--[[User:AndyE|AndyE]] 15:12, 12 January 2011 (UTC)
 
 
 
it might be better if, rather than laz0ring the same location multiple times, we converted the image to 8 shades of grey and then picked out each shade as a seperate layer with it's own power settings. that's what i was starting to try to do in the commented-out bit above - not sure how to pick out each shade.
 
probably worth experimenting with both methods on the laser cutter
 
--[[User:AndyE|AndyE]] 15:20, 12 January 2011 (UTC)
 
Seems to work pretty darn well.
Original
[[File:brushedsteeld20.jpg]]
 
Result ater rebuilding in GIMP
[[File:Rebuilt.jpg]]
 
If we wanted to get the same resolution we'd need to pick out 256 shades of grey to laser, or better still hack the laser software to allow us to control the burn strength per pixel.
 
 
Below is another example. It generates N times a B&W bitmap. Each is then fed to the laser and overlaid. So the darkest point gets N shots; the lightest just one or two. Note the log/lin mappings - which sort of do not apply to all materials!
 
<pre>
#!/usr/bin/perl
use GD;
 
# Number of successive burns
#
my $N = 4;
 
die "Syntax: $0 <image.png>"
unless $#ARGV==0;
my ($file) = @ARGV;
 
$in = GD::Image->new($file)
or die "Could not load '$file': $!\n";
 
$gray = new GD::Image($in->width, $in->height);
my @lin=();
map { $lin[$_] = $gray->colorAllocate($_,$_,$_); } (0 .. 255); ## linear - not eye or laser.
 
map {
        # calculate a cutoff point on an exp. scale. as this is what the burn
        # intensity versus grayness sort of is.
        #
push @coff,int(10 ** log($_)/log($N) + 0.5);
 
        # create output layer
my $layer = GD::Image->newPalette($gray->width, $gray->height);
$layer->colorAllocate(255,255,255) == 0 or die $.;
$layer->colorAllocate(0,0,0) == 1 or die $.;
push @out,$layer;
} (1 .. $N);
 
my @histogram = ();
 
for(my $x = 0; $x < $gray->width; $x++) {
for(my $y = 0; $y < $gray->height; $y++) {
my ($r,$g,$b) = $in->rgb($in->getPixel($x,$y));
# my $val = $g;
my $val = int((2*$r + 4*$g + $b)/7 + 0.5);
for(my $i = 0; $i < $N; $i++) {
$gray->setPixel($x,$y,$lin[ $val ]);
next unless $val > $coff[$i];
$out[$i]->setPixel($x,$y,1);
$histogram[$i]++;
};
};
};
map {
print "Layer $_\t$histogram[$_]\n";
} (0 .. $N-1);
 
open(FH,">gray.png") or die $!; print FH $gray->png; close(FH);
for(my $i = 0; $i < $N; $i++) {
open(FH,">layer_$i.png") or die $!;
print FH $out[$i]->png;
close(FH);
};
 
exit 0;
 
use SNMP;
 
&SNMP::initMib();
foreach my $oid (keys(%SNMP::MIB)) {
print "OID=", $oid, "\n";
        print "\tTYPE=", $SNMP::MIB{$oid}{'type'},
"\n\tLABEL=",$SNMP::MIB{$oid}{'label'}, "\n";
        print "\tDESCRIPTION=", $SNMP::MIB{$oid}{'description'}, "\n";
    }
</pre>
 
 
<hr>
 
OK, well its good to see that it's working more-or-less.
 
I've been trying to get it to accept a value instead of a percentage - it will - have to assume that MaxRGB = 256 (which depends on the settings when GraphicsMagick was compiled - so in a way it would be more portable to do it as a percentage - but values less than 1% appear to be rounded by GM).
 
so anyway, if we assume MaxRGB = 256 then it works OK.
 
http://hack.rs/cgi-bin/threshold_grayscale.pl
 
<pre>
 
#!/usr/bin/perl -w
use strict;
use CGI;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use List::Util qw(max min);
 
my $q = CGI->new();
 
print $q->header;
print $q->start_html;
 
print $q->p("this is a thing for doing threshholding");
print $q->p("<small>or possibly <i>thresholding</i>?</small>");
 
print $q->start_form( -enctype => "multipart/form-data" );
 
print $q->p("file");
print $q->filefield('uploaded_file');
print $q->submit();
 
print $q->end_form;
 
# do we have an upload?
my $filehandle = $q->upload('uploaded_file');
if (defined $filehandle) {
 
    # do shit
    print $q->p("I'm doing shit");
 
    # no, actually do shit
    my ($filename, $extension) = ($q->param('uploaded_file') =~ /^(\S+)\.(\S+)$/);
    my $tempfile = $q->tmpFileName($q->param('uploaded_file'));
 
    foreach my $i (0 .. 7) {
 
        my $n = 2 ** $i;
 
        my $outfile = "$filename"."_$i.$extension";
 
        my @ar = ("gm",
                  "convert",
                    "-operator", "Gray", "And", $n ,
                    "-operator", "Gray", "Threshold",  $n - 1  ,
                  $tempfile,
                  "/var/www/threshold_output/$outfile" );
 
        print $q->p("$i : " . join " ", @ar);
 
        system(@ar) == 0 or die "system call failed: $? $!"; #safer than passing a string to system(),
                                                            # because doing it this way bypasses the shell
 
        print $q->img({src => "/threshold_output/$outfile"});
    }
}
 
 
print $q->end_html;
 
</pre>
 
--[[User:AndyE|AndyE]] 12:21, 13 January 2011 (UTC)
 
<hr>

Latest revision as of 18:37, 16 January 2011

hi - what settings did you use for the test cake image? i didn't get the chance to do any other other night as the laser was screwed - so that's so far the only test image we have.

you think it needs less power?

is the combined-layers file on the laser's pc?

--AndyE 18:37, 16 January 2011 (UTC)

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