PHP | Gmagick setimagechanneldepth() Function

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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.zambiatek.com/wp-content/uploads/zambiatek-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

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