Imagick::setImageUnits()

(PECL imagick 2.0.0)

Sets the image units of resolution

说明

Imagick::setImageUnits(int $units): bool

Sets the image units of resolution.

参数

$units

返回值

成功时返回TRUE。

You should use the PHP Imagick constants to correctly set the Image Units, as described here: 
http://www.php.net/manual/en/imagick.constants.php
RESOLUTION constants
imagick::RESOLUTION_UNDEFINED (integer)
imagick::RESOLUTION_PIXELSPERINCH (integer)
imagick::RESOLUTION_PIXELSPERCENTIMETER (integer)

$source = 'miphoto.jpg';
$imagick = new Imagick($source);
$imagick -> setImageUnits(2); 
//0=undefined, 1=pixelsperInch, 2=PixelsPerCentimeter
$info = $imagick -> identifyImage();
print_r($info);
//ouput
/*
Array 
( 
[units] => PixelsPerCentimeter
)