How to apply MPSImageGuidedFilter in Swift

Question

I applied OpenCV guided filter for my project in Python successfully and now I have to carry this function to my iOS application. I searched Apple developer website and found out a filter called MPSImageGuidedFilter. I suppose it works in a similar way as OpenCV guided filter. However, my limited knowledge of iOS programming does not let me figure out how to use it. Unfortunately, I could not find a sample code on the web too. Is there anyone who used this filter before? I really appreciate the help. Or a sample code using any filter under MPS would be helpful to figure out.

Answer 1

After a few days of hard work, I managed to make MPSImageGUidedFilter. Please see below the code who wants to work on:

import UIKit
import MetalPerformanceShaders
import MetalKit

class ViewController: UIViewController {
    
    public var texIn: MTLTexture!
    
    public var coefficient: MTLTexture!

    public var context: CIContext!
    
    let device = MTLCreateSystemDefaultDevice()!
    var queue: MTLCommandQueue!
    var Metalview: MTKView { return view as! MTKView }

    override func viewDidLoad() {     
        super.viewDidLoad()
        
        Metalview.drawableSize.height = 412
        Metalview.drawableSize.width = 326
        Metalview.framebufferOnly = false
        Metalview.device = device
       
        Metalview.delegate = self
        
        queue = device.makeCommandQueue()
        let textureLoader = MTKTextureLoader(device: device)
        
        let urlCoeff = Bundle.main.url(forResource: "mask", withExtension: "png")
        do {
            coefficient = try textureLoader.newTexture(URL: urlCoeff!, options: [:])
        } catch {
            fatalError("coefficient file not uploaded")
        }
        
        let url = Bundle.main.url(forResource: "guide", withExtension: "png")
        do {
            texIn = try textureLoader.newTexture(URL: url!, options: [:])
        } catch {
            fatalError("resource file not uploaded")
        }
    }
    
}

extension ViewController: MTKViewDelegate {

    func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {}

    func draw(in view: MTKView) {
        guard let commandBuffer = queue.makeCommandBuffer(),
              let drawable = view.currentDrawable else {
            return
        }
      
        let shader = MPSImageGuidedFilter(device: device, kernelDiameter: 5)
        shader.epsilon = 0.001

        let textOut = drawable.texture
        
        shader.encodeReconstruction(to: commandBuffer, guidanceTexture: texIn, coefficientsTexture: coefficient, destinationTexture: textOut)

        commandBuffer.present(drawable)
        commandBuffer.commit()
    }

}