Imagick::blackThresholdImage

(PECL imagick 2, PECL imagick 3)

Imagick::blackThresholdImageForces all pixels below the threshold into black

说明

public Imagick::blackThresholdImage ( mixed $threshold ) : bool

Is like Imagick::thresholdImage() but forces all pixels below the threshold into black while leaving all pixels above the threshold unchanged.

参数

threshold

The threshold below which everything turns black

返回值

成功时返回 true

更新日志

版本 说明
PECL imagick 2.1.0 Now allows a string representing the color as a parameter. Previous versions allow only an ImagickPixel object.

范例

Example #1 Imagick::blackThresholdImage()

<?php
function blackThresholdImage($imagePath$thresholdColor) {
    
$imagick = new \Imagick(realpath($imagePath));
    
$imagick->blackthresholdimage($thresholdColor);
    
header("Content-Type: image/jpg");
    echo 
$imagick->getImageBlob();
}

?>

User Contributed Notes

Iddles 06-Jul-2011 05:35
You need to pass this function a colour:

<?php

$img
->blackThresholdImage( "#FFFFFF" );

?>

E.g. this blackens any pixel which isn't pure white.
elmer at web-axis dot net 30-Nov-2008 03:33
Here's a example of this function:

<?php
  $img
= new Imagick();
 
$img->readImage($image_file_name);
 
$img->blackThresholdImage('grey');
 
$img->writeImage($thumb_file_name);
 
$img->clear();
 
$img->destroy();
?>