How can I fix a Core Image's CILanczosScaleTransform filter border artifact?

Question

I want to implement an image downscaling algorithm for iOS. After reading that Core Images\'s CILanczosScaleTransform was a great fit for it, I implemented it the f

Answer 1

You can use imageByClampingToExtent.

Calling this method ... creates an image of infinite extent by repeating pixel colors from the edges of the original image.

You could use it like this:

...
guard let ciImage = CIImage(image: image)?.clampedToExtent() else {
    fatalError("Couldn't create CIImage from image in input")
}

See more information here: Apple Doc for clampedtoextent