# convolutionRGB7X7() Applies a convolution 7 x 7 filter to the RGB components of an image. ``` class func convolutionRGB7X7() -> any CIFilter & CIConvolution ``` ## Return Value The convolved image. ## Discussion This method applies a 7 x 7 convolution to the `RGB` components image. The effect uses a 7 x 7 area surrounding an input pixel, the pixel itself, and those within a distance of 3 pixels horizontally and vertically. The effect repeats this for every pixel within the image. The work area is then combined with the weight property vector to produce the processed image. This filter differs from the [`convolution7X7()`](/documentation/CoreImage/CIFilter-swift.class/convolution7X7()) filter, which processes all of the color components including the alpha component. The convolution-RGB 7 x 7 filter uses the following properties: - `inputImage`: A [`CIImage`](/documentation/CoreImage/CIImage) containing the image to process. - `weights`: A [`CIVector`](/documentation/CoreImage/CIVector) representing the convolution kernel. - `bias`: A `float` representing the value that’s added to each output pixel. > Note: > When using a nonzero `bias` value, the output image has an infinite extent. You should crop the output image before attempting to render it. The following code creates a filter that highlights edges in the input image: ```swift func convolutionRGB7X7(inputImage: CIImage) -> CIImage { let convolutionFilter = CIFilter.convolutionRGB7X7() convolutionFilter.inputImage = inputImage let weights: [CGFloat] = [ 0, 0, -1, -1, -1, 0, 0, 0, -1, -3, -3, -3, -1, 0, -1, -3, 0, 7, 0, -3, -1, -1, -3, 7, 25, 7, -3, -1, -1, -3, 0, 7, 0, -3, -1, 0, -1, -3, -3, -3, -1, 0, 0, 0, -1, -1, -1, 0, 0 ] let kernel = CIVector(values: weights, count: 49) convolutionFilter.weights = kernel convolutionFilter.bias = 0.0 return convolutionFilter.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)