PHP Manual: Creates a high-contrast, two-color image

Description

bool Imagick::randomThresholdImage ( float $low , float $high [, int $channel = Imagick::CHANNEL_ALL ] )

Changes the value of individual pixels based on the intensity of each pixel compared to threshold. The result is a high-contrast, two color image. This method is available if Imagick has been compiled against ImageMagick version 6.2.9 or newer.

Parameters

low: The low point
high: The high point
channel: 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.

Return Values

Returns TRUE on success.