Imagick::sigmoidalContrastImage

(PECL imagick 2.0.0)

Imagick::sigmoidalContrastImage — Adjusts the contrast of an image

说明

bool Imagick::sigmoidalContrastImage ( bool $sharpen , float $alpha , float $beta [, int $channel = Imagick::CHANNEL_ALL ] )

Adjusts the contrast of an image with a non-linear sigmoidal contrast algorithm. Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. Contrast indicates how much to increase the contrast (0 is none; 3 is typical; 20 is pushing it); mid-point indicates where midtones fall in the resultant image (0 is white; 50 is middle-gray; 100 is black). Set sharpen to TRUE to increase the image contrast otherwise the contrast is reduced.

参数

sharpen
alpha
beta
channel

返回值

成功时返回 TRUE。

错误／异常

错误时抛出 ImagickException。