PHP | Gmagick separateimagechannel() Function

The Gmagick::separateimagechannel() function is an inbuilt function in PHP which is used to separate a channel from the image and returns a grayscale image. A channel is a particular color component of each pixel in the image.

Syntax:

Gmagick Gmagick::separateimagechannel( int $channel )

Parameters: This function accepts a single parameter $channel which holds the integer value corresponding to one of the CHANNEL constants.

Return Value: This function returns Gmagick object on success.

Exceptions: This function throws GmagickException on error.

Below given programs illustrate the Gmagick::separateimagechannel() function in PHP:

Used Image:

Program 1 (Separating the RED channel):

<?php

// Create a new Gmagick object
$gmagick = new Gmagick('geeksforgeeks.png');

// Separate the Gmagick::CHANNEL_RED
$gmagick->separateimagechannel(Gmagick::CHANNEL_RED);

// Display the image
header("Content-Type: image/png");
echo $gmagick;
?>

Output:

Program 2 (Separating the Green channel):

<?php

// Create a new Gmagick object
$gmagick = new Gmagick('geeksforgeeks.png');

// Separate the Gmagick::CHANNEL_GREEN
$gmagick->separateimagechannel(Gmagick::CHANNEL_GREEN);

// Display the image
header("Content-Type: image/png");
echo $gmagick;
?>

Output:

Program 3 (For a drawing):

<?php

// Create a new Gmagick object
$gmagick = new Gmagick('geeksforgeeks.png');

// Create a GmagickDraw object
$draw = new GmagickDraw();

// Set the color
$draw->setFillColor('white');

// Function to draw rectangle
$draw->rectangle(0, 0, 800, 400);

// Set the fill color
$draw->setFillColor('yellow');

// Set the font size
$draw->setfontsize(50);

// Annotate a text
$draw->annotate(30, 100, 'GeeksforGeeks');

// Use of drawimage function
$gmagick->drawImage($draw);

// Separate the Gmagick::CHANNEL_BLUE
$gmagick->separateimagechannel(Gmagick::CHANNEL_BLUE);

// Display the output image
header("Content-Type: image/png");
echo $gmagick->getImageBlob();
?>

Output:

Reference: https://www.php.net/manual/en/gmagick.separateimagechannel.php