Creates a high-contrast, two-color image

# Imagick::randomThresholdImage

(PECL imagick 2, PECL imagick 3)

Imagick::randomThresholdImage — Creates a high-contrast, two-color image

### 说明

public function Imagick::randomThresholdImage(float `$low`, float `$high`, int `$channel` = Imagick::CHANNEL_DEFAULT): bool

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. 此方法在Imagick基于ImageMagick 6.2.9以上版本编译时可用。

### 参数

`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.

### 返回值

成功时返回 `true`。

### 示例

示例 #1 Imagick::randomThresholdImage()

    <?php
    function randomThresholdimage($imagePath, $lowThreshold, $highThreshold, $channel) {
        $imagick = new \Imagick(realpath($imagePath));

        $imagick->randomThresholdimage(
            $lowThreshold * \Imagick::getQuantum(),
            $highThreshold * \Imagick::getQuantum(),
            $channel
        );
        header("Content-Type: image/jpg");
        echo $imagick->getImageBlob();
    }

    ?>

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