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PHP | Imagick levelImage() Function

  • Last Updated : 08 Aug, 2019

The Imagick::levelImage() function is an inbuilt function in PHP which is used to adjust the levels of an image.

Syntax:

bool Imagick::levelImage( $blackPoint, $gamma, 
                   $whitePoint, $channel = Imagick::CHANNEL_DEFAULT ) 

Parameters: This function accepts four parameters as mentioned above and described below:

  • blackPoint: This parameter holds the black point of an image.
  • gamma: This parameter holds the value of gamma.
  • whitePoint: This parameter holds the white point of an image.
  • channel: This parameter holds the channel constant that is valid for channel mode. Use bit-wise operator to combine more then one channel.

Return Value: This function returns TRUE on success.

Errors/Exceptions: This function throws ImagickException on error.



Below program illustrates the Imagick::levelImage() function in PHP:

Program:




<?php
  
// Store the image into variable
$imagick=
  
// Declare new Imagick object
$imagick = new \Imagick($imagick);
  
// Use Imagick::newPseudoImage() function to create
// a new image using ImageMagick pseudo-formats
$imagick->newPseudoimage(700, 250, 'radial-gradient:red-blue');
  
// Function to set image format
$imagick->setFormat('png');
  
//  Use Imagick::getQuantum() function to
// return the ImageMagick quantum range
$quantum = $imagick->getQuantum();
  
// Use Imagick::levelImage() function
$imagick->levelImage($blackPoint / 100, $gamma, $quantum * $whitePoint / 100);
   
header("Content-Type: image/png");
  
// Display the image as output
echo $imagick->getImageBlob();
  
?>

Output:

Reference: https://www.php.net/manual/en/imagick.levelimage.php

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