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Ios swift – iOS how to make VariableBlur's CIFilter darker?

I am using the VariableBlur library in Swift to create a blur over my collection view under the status bar area as such:

I am trying to figure out how I can make the blur darker?

The library uses a CIFilter but I am not sure what to change to make it darker. I have already tried changing the UIBlurEffect(style: .regular) to use .dark but that didn’t make any difference.

And the color0 on ciGradientFilter is already set to black. In fact, changing it to red or any other color doesn’t make any difference.

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2

Answers


  1. 0

    A simple way is to just put your own black gradient below the VariableBlurView.

    Image("some image")
    .overlay(alignment: .top) {
        ZStack {
            LinearGradient(colors: [.black, .clear], startPoint: .top, endPoint: .bottom)
            VariableBlurView(maxBlurRadius: 20, direction: .blurredTopClearBottom)
        }
        .frame(height: 400)
    }

    Side-by-side comparison:

    enter image description here enter image description here

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  2. 0 
    //import CoreImage

func applyVariableBlurAndDarken(to image: UIImage) -> UIImage? {
    guard let ciImage = CIImage(image: image) else { return nil }
     // Apply VariableBlur Filter
    let variableBlurFilter = CIFilter(name: "CIMaskedVariableBlur")!
    variableBlurFilter.setValue(ciImage, forKey: kCIInputImageKey)
    variableBlurFilter.setValue(10.0, forKey: "inputRadius")  // Adjust the blur radius as needed
    
    guard let blurredImage = variableBlurFilter.outputImage else { return nil }
    
    // Apply Color Controls to darken the image
    let colorControlsFilter = CIFilter(name: "CIColorControls")!
    colorControlsFilter.setValue(blurredImage, forKey: kCIInputImageKey)
    colorControlsFilter.setValue(-0.5, forKey: kCIInputBrightnessKey) // Reduce brightness to darken
    colorControlsFilter.setValue(1.2, forKey: kCIInputContrastKey)   // Optional: increase contrast
    
    guard let darkenedImage = colorControlsFilter.outputImage else { return nil }
    
    // Render the final image
    let context = CIContext()
    guard let cgImage = context.createCGImage(darkenedImage, from: darkenedImage.extent) else { return nil }
    
    return UIImage(cgImage: cgImage)
}

// Usage
if let image = UIImage(named: "your_image_name") {
    let processedImage = applyVariableBlurAndDarken(to: image)
    // Now you can use the processedImage
}
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