# bumpDistortionLinear() Linearly distorts an image with a concave or convex bump. ``` class func bumpDistortionLinear() -> any CIFilter & CIBumpDistortionLinear ``` ## Return Value The distorted image. ## Discussion This method applies the bump distortion linear filter to an image. This effect creates a concave or convex bump to a linear portion of the image. The curvature of the bump is defined by the `scale` property. A value of 0.0 has no effect, while a positive value creates an outward curvature and a negative value creates an inward curvature. The bump distortion linear filter uses the following properties: - `inputImage`: An image with the type [`CIImage`](/documentation/CoreImage/CIImage). - `radius`: A `float` representing the amount of pixels the filter uses to create the distortion as an . - `center`: A set of coordinates marking the center of the image as a . - `scale`: A `float` representing the curvature of the bump effect as an . - `angle`: A `float` representing the angle of the distortion, in radians, as an . The following code creates a filter that results in a vertical bump distorting the image: ```swift func bumpDistortionLinear(inputImage: CIImage) -> CIImage { let filter = CIFilter.bumpDistortionLinear() filter.inputImage = inputImage filter.center = CGPoint(x: inputImage.extent.midX, y: inputImage.extent.midY) filter.radius = 500 filter.scale = 0.2 filter.angle = .pi/2 return filter.outputImage! } ```  --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)