| Re: Help with PHP BD imaging functionality [message #182486 is a reply to message #182484] |
Thu, 08 August 2013 07:58   |
The Natural Philosoph
Messages: 993
Registered: September 2010
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Senior Member |
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On 08/08/13 00:53, Ed Jay wrote:
> 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?
is the problem less that you don't know how to make GD do what you want,
then you don't actually know how to do what you want at all?
Is what you want covered by this?
http://www.php.net/manual/en/image.examples.merged-watermark.php
>
> $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,
--
Ineptocracy
(in-ep-toc’-ra-cy) – a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.
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