(PECL imagick 2.0.0)
Imagick::thresholdImage — Changes the value of individual pixels based on a threshold
$threshold
[, int $channel = Imagick::CHANNEL_ALL
] )Changes the value of individual pixels based on the intensity of each pixel compared to threshold. The result is a high-contrast, two color image.
threshold
channel
成功时返回 TRUE。
php t traction dot de (2012-06-29 07:25:11)
getQuantumRange() can be handy here:
<?php
$i = new Imagick($imageFile);
$max = $i->getQuantumRange();
$max = $max["quantumRangeLong"];
$i->thresholdImage(0.77 * $max);
?>