Imagick::blackThresholdImage

(PECL imagick 2, PECL imagick 3)

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

Description

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.

Parameters

threshold: The threshold below which everything turns black

Return Values

Returns true on success.

Changelog

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

Examples

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();
}

?>

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User Contributed Notes 2 notes

down

Iddles ¶

13 years ago

You need to pass this function a colour:

<?php

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

?>

E.g. this blackens any pixel which isn't pure white.

down

elmer at web-axis dot net ¶

16 years ago

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();

?>

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