Applying CIGaussianBlur to UIImage not working properly - ios

Question

I want a blur effect to UIImage as slider value changes.
I am using the CIGaussianBlur filter to blur the image.
The code is as follows
func applyBlurFilter(aCIImage: CIImage, val: CGFloat) -> UIImage {
let clampFilter = CIFilter(name: "CIAffineClamp")
clampFilter?.setDefaults()
clampFilter?.setValue(aCIImage, forKey: kCIInputImageKey)
let blurFilter = CIFilter(name: "CIGaussianBlur")
blurFilter?.setValue(clampFilter?.outputImage, forKey: kCIInputImageKey)
blurFilter?.setValue(val, forKey: kCIInputRadiusKey)
let rect = aCIImage.extent
if let output = blurFilter?.outputImage {
if let cgimg = self.context.createCGImage(output, from: rect) {
let processedImage = UIImage(cgImage: cgimg)
return processedImage
}
}
return image ?? self.image
}
Note: I've also tried the below code using CICrop filter
func applyBlurFilter(beginImage: CIImage, value: Float) -> UIImage? {
let currentFilter = CIFilter(name: "CIGaussianBlur")
currentFilter?.setValue(beginImage, forKey: kCIInputImageKey)
currentFilter?.setValue(value, forKey: kCIInputRadiusKey)
let cropFilter = CIFilter(name: "CICrop")
cropFilter?.setValue(currentFilter!.outputImage, forKey: kCIInputImageKey)
cropFilter?.setValue(CIVector(cgRect: beginImage!.extent), forKey: "inputRectangle")
let output = cropFilter?.outputImage
let context = CIContext(options: nil)
let cgimg = self.context.createCGImage(output!, from: beginImage!.extent)
let processedImage = UIImage(cgImage: cgimg!)
return processedImage
}
The code works perfectly with some images, but with bigger images, while applying the blur filter to the image, the image's right edges get transparent which I don't want.
Note: I am running this on device
What am I doing wrong here, I have no idea
The image whose right edge gets transparant
Result after applying GaussianBlur to the above image
Thanks!!

Answer 1

Well, you're doing something wrong somewhere. The absolute best advice I can give you in your career is to create a small test project to experiment when you have such an issue - I've done this for 15 years in the Apple world, and its been of enormous help.
I created a project here so you don't have to (this time). I downloaded the image, placed it in an ImageView, and it looked perfect (as expected). I then used your code (except I had to create a context, and guess at radius values, then ran it. Image looks perfect with a blur of 0, 5, 10, and 25.
Obviously the issue is something else you are doing. What I suggest is that you keep adding to the test project until you can find what step is the problem (context? other image processing?)
This is the entirety of my code:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let im1 = UIImage(named: "Image.jpg")!
let cim = CIImage(image: im1)!
let im2 = applyBlurFilter(aCIImage: cim, val: 25)
let iv = UIImageView(image: im2)
iv.contentMode = .scaleToFill
self.view.addSubview(iv)
}
func applyBlurFilter(aCIImage: CIImage, val: CGFloat) -> UIImage {
let clampFilter = CIFilter(name: "CIAffineClamp")
clampFilter?.setDefaults()
clampFilter?.setValue(aCIImage, forKey: kCIInputImageKey)
let blurFilter = CIFilter(name: "CIGaussianBlur")
blurFilter?.setValue(clampFilter?.outputImage, forKey: kCIInputImageKey)
blurFilter?.setValue(val, forKey: kCIInputRadiusKey)
let rect = aCIImage.extent
if let output = blurFilter?.outputImage {
let context = CIContext(options: nil)
if let cgimg = context.createCGImage(output, from: rect) {
let processedImage = UIImage(cgImage: cgimg)
return processedImage
}
}
fatalError()
}
}