(PECL imagick 2.0.0)
Imagick::negateImage — Negates the colors in the reference image
$channel= Imagick::CHANNEL_ALL ] )
Negates the colors in the reference image. The Grayscale option means that only grayscale values within the image are negated.
Whether to only negate grayscale pixels within the image.
Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channeltype constants using bitwise operators. Refer to this list of channel constants.
TRUE on success.
Throws ImagickException on error.