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Help with PHP BD imaging functionality [message #182484]

Wed, 07 August 2013 23:53

Ed Jay
Messages: 7
Registered: August 2013

Karma:

Junior Member

I'm trying to highlight a portion of a grayscale image, with the
highlighting color applied to pixels within a range of level only. I'm not
getting the result I seek.

While the grayscale values within the range possibly yield the highlight
color, the entire image is masked with the color from the last
imagecolorallocate.

My code follows, and the 'Process of interest' is the offending culprit.

How do I highlight the value-region of interest with the background of my
choosing?

$source_image = $_GET['source'];
$threshold = $_GET['threshold'];
$range = $_GET['range'];

$starting_img = imagecreatefromjpeg($source_image);
$img_data = getimagesize($source_image);
$width = $img_data[0];
$height = $img_data[1];
$final = imagecreatetruecolor($img_data[0],$img_data[1]);

$gray_threshold = 1*$threshold;
$gray_range = 1*$range;
$gray_top = ($gray_threshold + $gray_range);
if ($gray_top > 255) {$gray_top = 255;}
$highlight_color = imagecolorallocate($final,0,0,255);

//Process of interest:

for($x=0; $x<$width; $x++){
for($y=0; $y<$height; $y++){

$gray =(imagecolorat($final,$x,$y) >> 16) & 0xFF;
if (($gray > $gray_threshold) && ($gray < $gray_top)) {$gray =
$highlight_color;}
$gray2 = imagecolorallocate($final,$gray,$gray,$gray);
imagesetpixel($final, $x,$y,$gray2);

}
}

header('Content-Type: image/jpeg');
imagejpeg($final);
imagedestroy($starting_img);
imagedestroy($final);

Thanks in advance,
--
Ed Jay (remove 'M' to respond by email)

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[Message index]

		Help with PHP BD imaging functionality By: Ed Jay on Wed, 07 August 2013 23:53
		Re: Help with PHP BD imaging functionality By: The Natural Philosoph on Thu, 08 August 2013 07:58
		Re: Help with PHP BD imaging functionality By: Ed Jay on Thu, 08 August 2013 12:01
		Re: Help with PHP BD imaging functionality By: The Natural Philosoph on Thu, 08 August 2013 13:12
		Re: Help with PHP BD imaging functionality By: Christoph Michael Bec on Thu, 08 August 2013 23:13
		Re: Help with PHP BD imaging functionality By: Jerry Stuckle on Thu, 08 August 2013 12:55

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