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# sourceInCompositing()

Subtracts non-overlapping areas of two images, resulting in one image.

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

## Return Value

The modified image.

## Discussion

This method applies the source-in compositing filter to an image. The effect creates the result by overlaying the input image over the background image. The filter then removes the non-overlapping area of both images.

The source-in 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 portion of the background image that overlaps with the input:

```swift
func sourceInCompositing(inputImage: CIImage, backgroundImage: CIImage) -> CIImage {
    let colorBlendFilter = CIFilter.sourceInCompositing()
    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-in compositing filter. The result displays the overlapping area of the gradient image and beach image with all the non-overlapping image removed.](images/com.apple.coreimage/media-3546393@2x.png)

---

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