September Morn Update

Task/Hough-transform/Julia/hough-transform.julia

@@ -0,0 +1,6 @@
+using ImageFeatures
+
+img = fill(false,5,5)
+img[3,:] .= true
+
+println(hough_transform_standard(img))

Task/Hough-transform/Perl-6/hough-transform.pl6

@@ -0,0 +1,38 @@
+use GD;
+
+my $filename = 'pentagon.ppm';
+my $in = open($filename, :r, :enc<iso-8859-1>);
+my ($type, $dim, $depth) = $in.lines[^3];
+my ($xsize,$ysize) = split ' ', $dim;
+
+my ($width, $height) = 460, 360;
+my $image = GD::Image.new($width, $height);
+
+my @canvas = [255 xx $width] xx $height;
+
+my $rmax = sqrt($xsize**2 + $ysize**2);
+my $dr   = 2 * $rmax / $height;
+my $dth  = π / $width;
+
+my $pixel = 0;
+my %cstore;
+for $in.lines.ords -> $r, $g, $b {
+    $pixel++;
+    next if $r > 130;
+
+    my $x =       $pixel % $xsize;
+    my $y = floor $pixel / $xsize;
+
+    (0..^$width).race.map: -> $k {
+        my $th = $dth*$k;
+        my $r = ($x*cos($th) + $y*sin($th));
+        my $iry = ($height/2 + ($r/$dr).round(1)).Int;
+        my $c = '#' ~ (@canvas[$iry][$k]--).base(16) x 3;
+        %cstore{$c} = $image.colorAllocate($c) if %cstore{$c}:!exists;
+        $image.pixel($k, $iry, %cstore{$c});
+    }
+}
+
+my $png_fh = $image.open("hough-transform.png", "wb");
+$image.output($png_fh, GD_PNG);
+$png_fh.close;

Task/Hough-transform/Perl/hough-transform.pl

@@ -0,0 +1,39 @@
+use Imager;
+
+use constant pi => 3.14159265;
+
+sub hough {
+    my($im)     = shift;
+    my($width)  = shift || 460;
+    my($height) = shift || 360;
+    $height = 2 * int $height/2;
+
+    $height = 2 * int $height/2;
+    my($xsize, $ysize) = ($im->getwidth, $im->getheight);
+    my $ht = Imager->new(xsize => $width, ysize => $height);
+    for my $i (0..$height-1) { for my $j (0..$width-1) { $canvas[$i][$j] = 255 } }
+    $ht->box(filled => 1, color => 'white');
+
+    $rmax = sqrt($xsize**2 + $ysize**2);
+    $dr   = 2 * $rmax / $height;
+    $dth  = pi / $width;
+
+    for $x (0..$xsize-1) {
+      for $y (0..$ysize-1) {
+        my $col = $im->getpixel(x => $x, y => $y);
+        my($r,$g,$b) = $col->rgba;
+        next if $r==255; # && $g==255 && $b==255;
+        for $k (0..$width) {
+            $th = $dth*$k;
+            $r = ($x*cos($th) + $y*sin($th));
+            $iry = ($height/2 + int($r/$dr + 0.5));
+            $ht->setpixel(x => $k, y => $iry, color => [ ($canvas[$iry][$k]--) x 3] );
+        }
+      }
+    }
+    return $ht;
+}
+
+my $img = Imager->new;
+$img->read(file => 'ref/pentagon.png') or die "Cannot read: ", $img->errstr;
+$ht->write(file => 'hough_transform.png');

Task/Hough-transform/Phix/hough-transform.phix

@@ -0,0 +1,53 @@
+-- demo\rosetta\Hough_transform.exw
+include pGUI.e
+
+function hypot(atom a,b) return sqrt(a*a+b*b) end function
+
+function hough_transform(imImage im, integer width=460, height=360)
+    height = 2*floor(height / 2)
+    integer xsize = im_width(im),
+            ysize = im_width(im)
+    sequence ht = repeat(repeat(repeat(255,3),width),height)
+    sequence canvas = repeat(repeat(255,width),height)
+    atom rmax = hypot(xsize, ysize),
+         dr = 2*(rmax / height),
+         dth = (PI / width)
+    for y=0 to ysize-1 do
+        for x=0 to xsize-1 do
+            integer {r,g,b} = im_pixel(im, x, y)
+            if r!=255 then
+                for k=1 to width do
+                    atom th = dth*(k-1),
+                         r2 = (x*cos(th) + y*sin(th))
+                    integer iry = (height/2 + floor(r2/dr + 0.5))+1,
+                            cik = canvas[iry][k] - 1
+                    canvas[iry][k] = cik
+                    ht[iry][k] = repeat(cik,3)
+                end for
+            end if
+        end for
+    end for
+    ht = flatten(ht) -- (needed by IupImageRGB)
+    Ihandle new_img = IupImageRGB(width, height, ht)
+    return new_img
+end function
+
+IupOpen()
+
+atom pError = allocate(machine_word())
+imImage im1 = imFileImageLoadBitmap("Pentagon.png",0,pError)
+if im1=NULL then ?"error opening Pentagon.png" abort(0) end if
+Ihandln image1 = IupImageFromImImage(im1),
+        image2 = hough_transform(im1),
+        label1 = IupLabel(),
+        label2 = IupLabel()
+IupSetAttributeHandle(label1, "IMAGE", image1)
+IupSetAttributeHandle(label2, "IMAGE", image2)
+
+Ihandle dlg = IupDialog(IupHbox({label1, label2}))
+IupSetAttribute(dlg, "TITLE", "Hough transform")
+IupCloseOnEscape(dlg)
+IupShow(dlg)
+
+IupMainLoop()
+IupClose()