Hello, I am very new to perl so hopefully this is something simple. I have a script that reads a data file and creates a png image based on the data for each record in the file. The first pass through the loop the image created in 56kb, all the rest of the images are 145kb. In the while loop, I am creating a new image object for each pass. I am guessing I need to destroy the image object before creating the new one but I am not sure how.

When I first built this, every image after the first one had a black background and I had to place a white rectangle on the image first to make the background white. I think the black background is where the extra size is coming from.

Any suggestions would be appreciated.

Thanks

George

Code snippet is below: 

#!/usr/bin/perl
    use GD;
# size of image
$maxx = 600;
$maxy = 500;
$numGrids = 33;
# A background inmage to add
open (PNG,"gradient/river.png") || die;
      $mapImage = newFromPng GD::Image(\*PNG) || die;
      close PNG;

open(FILENAME,"gradient/current_r") || die "open failed";
{
   
   my @tmp;
   my @data;
   my $line1 = <FILENAME>;
   $count=0;
   while ($line2 = <FILENAME>)
   {
       @tmp = split(' ', $line2);
       @PRESOBS = @tmp;
        # create a new image
        $im = new GD::Image($maxx+50,$maxy); # enough for y axis label
+s
        $im->trueColor(1);

        # allocate some colors
        $white = $im->colorAllocate(255,255,255);
        $black = $im->colorAllocate(0,0,0);
        #$red = $im->colorAllocate(255,0,0);
        #$blue = $im->colorAllocate(0,0,255);
        $grey = $im->colorAllocate(128, 128, 128);
        #$green= $im->colorAllocate(0, 255, 0);

        # make the background transparent and interlaced

        $im->transparent($white);
        $im->interlaced('true');
# hack added to images after the first one do not have a black backgro
+und
        $im->filledRectangle(0,0,$maxx+50, $maxy, $white);


.... Code here to draw the image elements


    #Load map image
        $im->copy($mapImage, 0, $maxy/2+1, 0,0,600,250);
        # Put a black frame around the picture
        $im->rectangle(0,0,$maxx-1,$maxy-1,$black);
        $im->line(0, $maxy/2, $maxx, $maxy/2, $black);

        $png_data = $im->png;
        $hour = sprintf("%02d", $PRESOBS[0]);
        $xnum = sprintf("%d", $count);
        my $file = "EtaGradient". $xnum.".png";
        open(DISPLAY,">$file") || die "open failed";
        binmode DISPLAY;
        print DISPLAY $png_data;
        close DISPLAY;
        print "Output file = ".$file."\n";
        $count++;
    }
    close (FILENAME);
}

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In reply to Images created in a loop grow by gtm

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