PHP | Imagick getImageChannelExtrema() Function

The Imagick::getImageChannelExtrema() function is an inbuilt function in PHP which is used to get the extrema for one or more image channels. Extrema are the points at which a maximum or minimum value of a function is observed. It returns an associative array with the keys “minima” and “maxima”.

Syntax:

array Imagick::getImageChannelExtrema(int $channel)

Parameters: This function accepts single parameter $channel which specifies the channel constant that is valid for your channel mode. Use bitwise operator to combine channeltype constants.

Exceptions: This function throws ImagickException on error.

Return Value: This function returns TRUE on success.

Below programs illustrate the Imagick::getImageChannelExtrema() function in PHP:

Program 1:

<?php

// Create new imagick object
$imagick = new Imagick(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-13.png');

// Get the extrema with CHANNEL constant as 0
// which corresponds to imagick::CHANNEL_UNDEFINED
$extrema = $imagick->getImageChannelExtrema(0);
print_r($extrema);
?>

Output:

Array ( [minima] => 0 [maxima] => -9223372036854775808 )

Program 2:

<?php

// Create new imagick object
$imagick = new Imagick(
'https://media.geeksforgeeks.org/wp-content/uploads/20190918234528/colorize1.png');

// Get the extrema with CHANNEL constant as 6
// which corresponds to imagick::CHANNEL_BLUE
$extrema = $imagick->getImageChannelExtrema(6);
print_r($extrema);
?>

Output:

Array ( [minima] => 5654 [maxima] => 65535 )

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