(PECL imagick 2, PECL imagick 3)
Imagick::setImageUnits — Sets the image units of resolution
Sets the image units of resolution.
units
Returns true on success.
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
)