Imagick::thresholdImage()

(PECL imagick 2.0.0)

Changes the value of individual pixels based on a threshold

说明

Imagick::thresholdImage(float $threshold[,int $channel= Imagick::CHANNEL_DEFAULT]): bool

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.

参数

$threshold

$channel

返回值

成功时返回TRUE。

范例

Example #1 Imagick::thresholdImage()

<?php
function thresholdimage($imagePath, $threshold, $channel) {
    $imagick = new \Imagick(realpath($imagePath));
    $imagick->thresholdimage($threshold * \Imagick::getQuantum(), $channel);
    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}
?>

getQuantumRange() can be handy here:
<?php
$i = new Imagick($imageFile);
$max = $i->getQuantumRange();
$max = $max["quantumRangeLong"]; 
$i->thresholdImage(0.77 * $max);
?>