PHP Manual: Changes the color value of any pixel that matches target

Description

bool Imagick::opaquePaintImage ( mixed $target , mixed $fill , float $fuzz , bool $invert [, int $channel = Imagick::CHANNEL_DEFAULT ] )

Changes any pixel that matches color with the color defined by fill. This method is available if Imagick has been compiled against ImageMagick version 6.3.8 or newer.

Parameters

target: ImagickPixel object or a string containing the color to change
fill: The replacement color
fuzz: The amount of fuzz. For example, set fuzz to 10 and the color red at intensities of 100 and 102 respectively are now interpreted as the same color.
invert: If TRUE paints any pixel that does not match the target color.
channel: Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channel constants using bitwise operators. Defaults to Imagick::CHANNEL_DEFAULT. Refer to this list of channel constants

Return Values

Returns TRUE on success.