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# sourceAtopCompositing()

Overlaps two images to create one cropped image.

```
class func sourceAtopCompositing() -> any CIFilter & CICompositeOperation
```

## Return Value

The modified image.

## Discussion

This method applies the source-atop compositing filter to an image. The effect creates the result by overlaying the input image over the background image. The filter then removes the area that doesn’t overlap with the background image.

The source-atop compositing filter uses the following properties:

- `inputImage`: An image with the type [`CIImage`](/documentation/CoreImage/CIImage).
- `backgroundImage`: An image with the type [`CIImage`](/documentation/CoreImage/CIImage).

The following code creates a filter that results in an output image that shows the background image with the portion of the input image that overlaps it:

```swift
func sourceAtopCompositing(inputImage: CIImage, backgroundImage: CIImage) -> CIImage {
    let colorBlendFilter = CIFilter.sourceAtopCompositing()
    colorBlendFilter.inputImage = inputImage
    colorBlendFilter.backgroundImage = backgroundImage
    return colorBlendFilter.outputImage!
}
```

![The image on the top left shows a beach with multiple palm trees and a rainbow arching across the blue sky.  The image below is a gradient image displaying a gradual color shift from purple to a dark orange. The image on the right shows the output from applying a source-atop compositing filter. The result displays the overlapping area of the gradient image showing on the beach photo with no changes to color in either image.](images/com.apple.coreimage/media-3546396@2x.png)

---

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