Imagick::linearStretchImage

(PECL imagick 2.0.0)

Imagick::linearStretchImage — Stretches with saturation the image intensity

说明

Imagick::linearStretchImage ( float $blackPoint , float $whitePoint ) : bool

Stretches with saturation the image intensity.

参数

blackPoint: The image black point
whitePoint: The image white point

返回值

成功时返回 TRUE。

范例

Example #1 Imagick::linearStretchImage()


<?php
function linearStretchImage($imagePath, $blackThreshold, $whiteThreshold) {
    $imagick = new \Imagick(realpath($imagePath));
    $pixels = $imagick->getImageWidth() * $imagick->getImageHeight();
    $imagick->linearStretchImage($blackThreshold * $pixels, $whiteThreshold * $pixels);

    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}

?>

User Contributed Notes

SkepticaLee 11-Jun-2014 12:54


"Black" and "white" points here are pixel counts from the darkest and brightest ends respectively. To turn the darkest 90% of the pixels black, and the brightest 5% white, use the following:



<?php

$im = new Imagick ("some image.png");

list ($width, $height) = array_values ($im->getImageGeometry ());

$px = $width * $height;

$im->modulateImage (100, 0, 100);

$im->linearStretchImage ($px * 0.9, $px * 0.05);

$im->writeImage ("temp.jpg");

?>