Imagick
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Imagick::blackThresholdImage

(PECL imagick 2.0.0)

Imagick::blackThresholdImage — Forces all pixels below the threshold into black

说明

bool Imagick::blackThresholdImage ( mixed $threshold )

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

Imagick
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PHP手册 - N: Forces all pixels below the threshold into black

用户评论:

Iddles (07-Jul-2011 01:35)

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 11:33)

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();
?>