The predefined constant values listed here are wrong. The correct values can be found at:
www.php.net/manual/de/gmagick.constants.php
They are:
Gmagick::IMGTYPE_UNDEFINED (integer)
Gmagick::IMGTYPE_BILEVEL (integer)
Gmagick::IMGTYPE_GRAYSCALE (integer)
Gmagick::IMGTYPE_GRAYSCALEMATTE (integer)
Gmagick::IMGTYPE_PALETTE (integer)
Gmagick::IMGTYPE_PALETTEMATTE (integer)
Gmagick::IMGTYPE_TRUECOLOR (integer)
Gmagick::IMGTYPE_TRUECOLORMATTE (integer)
Gmagick::IMGTYPE_COLORSEPARATION (integer)
Gmagick::IMGTYPE_COLORSEPARATIONMATTE (integer)
Gmagick::IMGTYPE_OPTIMIZE (integer)
The $image_Type parameter can be one of these constants:
imagick::IMGTYPE_UNDEFINED (integer)
imagick::IMGTYPE_BILEVEL (integer)
imagick::IMGTYPE_GRAYSCALE (integer)
imagick::IMGTYPE_GRAYSCALEMATTE (integer)
imagick::IMGTYPE_PALETTE (integer)
imagick::IMGTYPE_PALETTEMATTE (integer)
imagick::IMGTYPE_TRUECOLOR (integer)
imagick::IMGTYPE_TRUECOLORMATTE (integer)
imagick::IMGTYPE_COLORSEPARATION (integer)
imagick::IMGTYPE_COLORSEPARATIONMATTE (integer)
imagick::IMGTYPE_OPTIMIZE (integer)
See section "IMGTYPE constants" at http://www.php.net/manual/en/imagick.constants.php