PHP | Imagick setImageAlphaChannel() Function

The Imagick::setImageAlphaChannel() function is an inbuilt function in PHP which is used to set the image alpha channel.

Syntax:

bool Imagick::setImageAlphaChannel( int $mode )

Parameters: This function accepts single parameter $mode which holds an integer value corresponding to one of the ALPHACHANNEL constants.

List of ALPHACHANNEL constants are given below:

• imagick::ALPHACHANNEL_ACTIVATE (0)
• imagick::ALPHACHANNEL_DEACTIVATE (1)
• imagick::ALPHACHANNEL_RESET (2)
• imagick::ALPHACHANNEL_SET (3)
• imagick::ALPHACHANNEL_UNDEFINED (4)
• imagick::ALPHACHANNEL_COPY (5)
• imagick::ALPHACHANNEL_EXTRACT (6)
• imagick::ALPHACHANNEL_OPAQUE (7)
• imagick::ALPHACHANNEL_SHAPE (8)
• imagick::ALPHACHANNEL_TRANSPARENT (9)

Return Value: This function returns TRUE on success.

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

Program 1:

<?php

// Create a new imagick object
$imagick = new Imagick(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-9.png');

// Set background color
$imagick->setImageBackgroundColor('blue');

// Set the ImageAlphaChannel to 9 which corresponds
// to imagick::ALPHACHANNEL_TRANSPARENT
$imagick->setImageAlphaChannel(9);

// Display the image
header("Content-Type: image/png");

echo $imagick->getImageBlob();
?>

Output:

Program 2:

<?php

// Create a new imagick object
$imagick = new Imagick(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-9.png');

// Set the ImageAlphaChannel to 3 which corresponds to
// imagick::ALPHACHANNEL_SET
$imagick->setImageAlphaChannel(3);

// Display the image
header("Content-Type: image/png");

echo $imagick->getImageBlob();
?>

Output:

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