# Imagick::compareImageLayers

(PECL imagick 2, PECL imagick 3)

Imagick::compareImageLayers — Returns the maximum bounding region between images

### 说明

public Imagick::compareImageLayers(int `$method`): Imagick

Compares each image with the next in a sequence and returns the maximum bounding region of any pixel differences it discovers. 此方法在Imagick基于ImageMagick 6.2.9以上版本编译时可用。

### 参数

`method`

  One of the layer method constants.

### 返回值

成功时返回 `true`。

### 错误／异常

错误时抛出 ImagickException。

### 示例

示例 #1 Using Imagick::compareImageLayers()

Comparing image layers

`<?php
/* create new imagick object */
$im = new Imagick("test.gif");
/* optimize the image layers */
$result = $im->compareImageLayers(imagick::LAYERMETHOD_COALESCE);
/* work on the $result */
?>`

### 参见

- Imagick::optimizeImageLayers() - Removes repeated portions of images to optimize
- Imagick::writeImages() - Writes an image or image sequence
- Imagick::writeImage() - 把图片写入指定的文件

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