             cell.titleLabel.text = "RGBAF"
             cell.imageView.image = self.rgbafImage
             cell.backgroundColor = backgroundColor
+        case 3:
+            cell.titleLabel.text = "RGBAF w/ mask"
+            cell.imageView.image = self.rgbafImageWithMask
+            cell.backgroundColor = backgroundColor
         default:
             cell.titleLabel.text = "(unknown)"
             cell.backgroundColor = UIColor.orange

    var originalImage: UIImage!
    var rgba8Image: UIImage?
    var rgbafImage: UIImage?
    

    // A simple way to make changes, allowing for visual inspection of changes
    var offset: Int = 0
    func timerHandler() {
        guard let originalImage = self.originalImage else { return }
        DispatchQueue.main.async {
            self.createRGBA8Image(offset: self.offset)
            self.createRGBAFImage(offset: self.offset)
            
            self.collectionView!.reloadData()
        }
        self.offset += 1
        if self.offset >= Int(originalImage.size.height/2) || self.offset >= Int(originalImage.size.width/2) {
            self.offset = 0
        }
    }


    // MARK: Image Generators
    func createRGBA8Image(offset: Int) {
        guard let originalImage = self.originalImage else { return }
        guard var dtsImage = DTSImageRGBA8(image: originalImage) else { print("Error creating image"); return }
        
        let red = DTSPixelRGBA8(red: 1.0, green: 0.5, blue: 0.5, alpha: 1.0)
        for y in 0..<dtsImage.height {
            dtsImage.setPixel(x: y - offset, y: y + offset, pixel: red)
        }
        
        self.rgba8Image = dtsImage.toUIImage()
    }

    func createRGBAFImage(offset: Int) {
        guard let originalImage = self.originalImage else { return }
        guard var dtsImage = DTSImageRGBAF(image: originalImage) else { print("Error creating image"); return }
        
        let blue = DTSPixelRGBAF(red: 0.2, green: 0.15, blue: 1.0, alpha: 1.0)
        

    // MARK: UICollectionViewDataSource

    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 4
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
