For format see:
http://www.imagemagick.org/script/formats.php
(PECL imagick 2.0.0)
Imagick::setFormat — Sets the format of the Imagick object
$format
)Sets the format of the Imagick object.
format
Returns TRUE
on success.
You can only set format listed in $imgic->queryFormats() .
It can be different from http://www.imagemagick.org/script/formats.php .