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ignace

Performance image scanning

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Hi,

 

I'm writing a script that scans images for numberplate edges in different angles. The below script works and picks up the edges in ~2 seconds. I'm curious if I can improve this to find the edges even faster.

 

real    0m1.917s
user    0m1.767s
sys     0m0.125s

<?php

require __DIR__ . '/../vendor/autoload.php';

use Imagine\Image\Palette\Color\ColorInterface;
use Imagine\Image\PointInterface;
use Imagine\Image\ImageInterface;
use Imagine\Image\Point;

$topLeft = $bottomLeft = [99999, 0];
$topRight = $bottomRight = [0, 99999];

$gatherer = function (ColorInterface $color, PointInterface $point, ImageInterface $image) use (&$topLeft, &$topRight, &$bottomLeft, &$bottomRight) {

    if ($color->getAlpha() == 0) {
        return;
    }

    $x = $point->getX();
    $y = $point->getY();

    $top    = $image->getColorAt(new Point($x, $y - 1))->isOpaque();
    $bottom = $image->getColorAt(new Point($x, $y + 1))->isOpaque();
    $left   = $image->getColorAt(new Point($x - 1, $y))->isOpaque();
    $right  = $image->getColorAt(new Point($x + 1, $y))->isOpaque();

    if (!$top && !$left && $bottom && $right && $x < $topLeft[0]) {
        $topLeft = [$x, $y];
    }

    if (!$top && !$right && $bottom && $left && $x > $topRight[0]) {
        $topRight = [$x, $y];
    }

    if (!$bottom && !$left && $top && $right && $x < $bottomLeft[0]) {
        $bottomLeft = [$x, $y];
    }

    if (!$bottom && !$right && $top && $left && $x > $bottomRight[0]) {
        $bottomRight = [$x, $y];
    }
};

//$img = (new \Imagine\Gd\Imagine())->open(__DIR__ . '/numberplate-test.png');
$img = (new \Imagine\Gd\Imagine())->open(__DIR__ . '/numberplate-test2.png');

for ($top = 640; $top < 900; $top++) {
    for ($left = 340; $left < 1580; $left++) {
        $point = new Point($left, $top);

        $gatherer($img->getColorAt($point), $point, $img);
    }
}

var_dump($topLeft, $topRight, $bottomLeft, $bottomRight);

post-22476-0-74816000-1487582759_thumb.png

post-22476-0-24703200-1487582766_thumb.png

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