PHP Imagick setImageChannelDepth()用法及代码示例

Imagick::setImageChannelDepth()函数是PHP中的内置函数，用于设置特定通道图像的深度。

用法:

bool Imagick::setImageChannelDepth( $channel, $depth )

参数：该函数接受上述和以下描述的两个参数：

$channel:此参数用于指定通道常数。以下是固定频道列表：
CHANNEL constants:
- imagick::CHANNEL_UNDEFINED
- imagick::CHANNEL_RED
- imagick::CHANNEL_GRAY
- imagick::CHANNEL_CYAN
- imagick::CHANNEL_GREEN
- imagick::CHANNEL_MAGENTA
- imagick::CHANNEL_BLUE
- imagick::CHANNEL_YELLOW
- imagick::CHANNEL_ALPHA
- imagick::CHANNEL_OPACITY
- imagick::CHANNEL_MATTE
- imagick::CHANNEL_BLACK
- imagick::CHANNEL_INDEX
- imagick::CHANNEL_ALL
- imagick::CHANNEL_DEFAULT
$depth:此参数用于指定要为Imagick对象设置的深度。

返回值：成功时此函数返回True。

以下示例程序旨在说明PHP中的Imagick::setImageChannelDepth()函数：

原始图片：

程序1:

<?php 
  
// Create new Imagick object 
$im = new Imagick( 
'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(imagick::CHANNEL_RED) . "</br>"; 
  
// Set channel Depth of CYAN and GREEN Channel 
$im->setImageChannelDepth(imagick::CHANNEL_RED, 4); 
  
echo "After Set Channel depth: " . "</br>"; 
echo $im->getImageChannelDepth(imagick::CHANNEL_RED) . "</br>"; 
?>

输出：

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

原始图片：

程序2:

<?php  
  
$string = "Computer Science portal for Geeks!";  
  
// Creating new image of above String  
// and add color 
$im = new Imagick();  
$draw = new ImagickDraw();  
  
// Fill the color in image  
$draw->setFillColor(new ImagickPixel('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 ImagickPixel('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(imagick::CHANNEL_GREEN) . "</br>"; 
  
// Set channel Depth of Green Channel 
$im->setImageChannelDepth(imagick::CHANNEL_GREEN, 8); 
  
echo "After Set Channel depth: " . "</br>"; 
echo $im->getImageChannelDepth(imagick::CHANNEL_GREEN) . "</br>"; 
?>

输出：

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

参考： http://php.net/manual/en/imagick.setimagechanneldepth.php

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注：本文由纯净天空筛选整理自R_Raj大神的英文原创作品 PHP | Imagick setImageChannelDepth() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。