ocpaul20 Posted September 8, 2010 Share Posted September 8, 2010 I am trying to produce a thresholded image with only an rgb value of zero or 255. As you can see, although I only output 0 and 255, I am finding that if I output as jpg file, I get other values in there as well. If I output as gif, I also get other values in there too. I am sure I am doing something stupid as there must be a way to do this. My test file is this attached jpg greyscale file. Is there a way to process this test file so that only 0 or 255 appears in the output image please? Thanks. Here is my program <?php $url = 'greyscale_image.jpg'; $outfile = 'greyscaleout'; $src = imagecreatefromjpeg($url); $w = imagesx($src);$h = imagesy($src); $loband = 80;$hiband = 255; $im_r = imagecreatetruecolor($w,$h); imagefill($im_r,0,0,imagecolorallocate($im_r,255,0,0)); $im_j = imagecreatetruecolor($w,$h); imagefill($im_j,0,0,imagecolorallocate($im_j,255,0,0)); for ($x=0;$x<$w;$x++) { for ($y=0;$y<$h;$y++) { $idx = imagecolorat($src,$x,$y); $rgb = imagecolorsforindex($src,$idx); // this is safest (for gifs) rather than some calculation - apparently $r =$rgb['red']; $g = $rgb['green']; $b = $rgb['blue']; $gryout = $r; if ($r <= $loband) { $gryout = 0; // everything less than= loband is black } if ($r > $loband) { $gryout = 255; // everything else is white } if ( ($gryout == 0) || ($gryout == 255) ) { // only zero or 255 allowed $idx = imagecolorallocate($im_r,$gryout,$gryout,$gryout); imagesetpixel($im_r,$x,$y,$idx); // imagesetpixel($im_j,$x,$y,$idx); // $idx2 = imagecolorat($im_r,$x,$y);// if ($idx != $idx2) { die($idx2." at x,y ".$x.",".$y); } $rgb = imagecolorsforindex($im_r,$idx); // this is safest (for gifs) rather than some calculation - apparently $r =$rgb['red']; $g = $rgb['green']; $b = $rgb['blue']; if ($r != 0) { if ($r != 255) { die($r." at x,y ".$x.",".$y); } } } else { die('<br>Grey going out to image is '.$gryout); } } } imagegif($im_r,$outfile.'.gif');imagedestroy($im_r); imagejpeg($im_j,$outfile.'.jpg');imagedestroy($im_j); // ========================== // done the writing, now check it // ========================== // $outfile = 'greyscale_image'; // test using original $src = imagecreatefromjpeg($outfile.'.jpg'); $w = imagesx($src);$h = imagesy($src); $errcount = 0; $x = 0; while($x<$w) { $y = 0; while($y<$h) { $idx = imagecolorat($src,$x,$y);// $rgb = imagecolorsforindex($src,$idx); // this is safest (for gifs) rather than some calculation $r =$rgb['red']; $g = $rgb['green']; $b = $rgb['blue']; if ($r != 0) { if ($r != 255) { echo sprintf('<br>r(%d,%d) r=%d g=%d b=%d',$x,$y,$r,$g,$b);$errcount++; } } if ($g != 0) { if ($g != 255) { echo sprintf('<br>g(%d,%d) r=%d g=%d b=%d',$x,$y,$r,$g,$b);$errcount++; } } if ($b != 0) { if ($b != 255) { echo sprintf('<br>b(%d,%d) r=%d g=%d b=%d',$x,$y,$r,$g,$b);$errcount++; } } if ($errcount > 10) {break 2;} $y++; } $x++; } if ($errcount == 0) {die( ' Checked OK' );} die( ' Checked NOT OK' ); // ================= ?> [attachment deleted by admin] Quote Link to comment Share on other sites More sharing options...
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