PHP | Gmagick setimagechanneldepth() Function

The Gmagick::setimagechanneldepth() function is an inbuilt function in PHP which is used to set the depth of a particular channel image.

Syntax:

Gmagick Gmagick::setimagechanneldepth( $channel , $depth )

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

• $channel: This parameter is used to specify the channel constant. Below is the list of constant channel:
  CHANNEL constants:
  
  
  • Gmagick::CHANNEL_UNDEFINED
  • Gmagick::CHANNEL_RED
  • Gmagick::CHANNEL_GRAY
  • Gmagick::CHANNEL_CYAN
  • Gmagick::CHANNEL_GREEN
  • Gmagick::CHANNEL_MAGENTA
  • Gmagick::CHANNEL_BLUE
  • Gmagick::CHANNEL_YELLOW
  • Gmagick::CHANNEL_ALPHA
  • Gmagick::CHANNEL_OPACITY
  • Gmagick::CHANNEL_MATTE
  • Gmagick::CHANNEL_BLACK
  • Gmagick::CHANNEL_INDEX
  • Gmagick::CHANNEL_ALL
  • Gmagick::CHANNEL_DEFAULT
• $depth: This parameter is used to specify the depth to be set for Gmagick object.

Return Value: This function returns the Gmagick object on success.

Below programs illustrate the Gmagick::setimagechanneldepth() function in PHP:

Program 1:
Original Image:

<?php

// Create new Gmagick object
$im = new Gmagick(
'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-15.png');

// Using getImageChannelDepth function
// with red channel
echo "Before Set Channel depth: " . "</br>";
echo $im->getImageChannelDepth(Gmagick::CHANNEL_RED) . "</br>";

// Set channel Depth of CYAN and GREEN Channel
$im->setimagechanneldepth(Gmagick::CHANNEL_RED, 4);

echo "After Set Channel depth: " . "</br>";
echo $im->getImageChannelDepth(Gmagick::CHANNEL_RED) . "</br>";

?>

Output:

Before Set Channel depth:
8
After Set Channel depth:
4

Program 2:
Original Image:

<?php

$string = "Computer Science portal for Geeks!";

// Creating new image of above String
// and add color
$im = new Gmagick();
$draw = new GmagickDraw();

// Fill the color in image
$draw->setFillColor(new GmagickPixel('green'));

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

$metrix = $im->queryFontMetrics($draw, $string);
$draw->annotation(0, 40, $string);
$im->newImage($metrix['textWidth'], $metrix['textHeight'],
        new GmagickPixel('white'));

// Draw the image
$im->drawImage($draw);
$im->setImageFormat('jpeg');

// Using getImageChannelDepth function
// with red channel
echo "Before Set Channel depth: " . "</br>";
echo $im->getImageChannelDepth(Gmagick::CHANNEL_GREEN) . "</br>";

// Set channel Depth of Green Channel
$im->setimagechanneldepth(Gmagick::CHANNEL_GREEN, 8);

echo "After Set Channel depth: " . "</br>";
echo $im->getImageChannelDepth(Gmagick::CHANNEL_GREEN) . "</br>";

?>

Output:

Before Set Channel depth:
16
After Set Channel depth:
8

Reference: http://php.net/manual/en/gmagick.setimagechanneldepth.php