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

<?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

<?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: https://www.php.net/manual/en/gmagick.setimagechanneldepth.php

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