How to get the percentage by which images are similar or different from each other using Imagic::compareImages?

Question

PHP

I have two pictures which I am trying to compare like this:

$result = $image1->compareImages($image2, Imagick::METRIC_MEANSQUAREERROR);
$result[0]->setImageFormat("png");

this returns me an array:

Array ( [0] => Imagick Object ( ) [1] => 3.5163383008121E-5 )

Is it possible to get a percentage of how similar / different these pictures are?