(PECL imagick 2, PECL imagick 3)
Imagick::contrastStretchImage — Enhances the contrast of a color image
$black_point
, float$white_point
, int$channel
= Imagick::CHANNEL_DEFAULT): boolEnhances the contrast of a color image by adjusting the pixels color to span the entire range of colors available. 此方法在Imagick基于ImageMagick 6.2.9以上版本编译时可用。
black_point
The black point.
white_point
The white 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. Imagick::CHANNEL_ALL
. Refer to this list of channel constants.
成功时返回 true
。