iOS.OldFilmFilter

Xamarin.iOS recipe using Core Image Filters to apply an Old Film effect

This is my sample recipe for the Xamarin Recipe Cook-Off. This sample will show how to take an image with your device and apply an old film effect. To handle the picture taking code I used the Xamarin.Mobile component.

Screenshot

How to apply Old Film Effect

The process involves applying a Sepia Tone filter, generating random white-specks (colored noise) and blending them together.

1. Apply the Sepia Tone filter to the image:

   var sep = new CISepiaTone() 
   {
   Image = ciimage,
   Intensity = 1F
   };
   

2. Create random white-specks. This process involves generating colored noise by calling RandomGenerator() and then processing the noise so that we only get white specks calling ColorMatrix().

   public CIImage ColorMatrix()
   {
   var rVector = new CIVector (0F, 0.1F, 0F, 0F); 
   var gVector = new CIVector (0F, 0.1F, 0F, 0F);  
   var bVector = new CIVector (0F, 0.1F, 0F, 0F); 
   var biasVector = new CIVector (0F, 0F, 0F, 0F); 
   
   var colorMatrix = new CIColorMatrix ()
   {
       Image = RandomGenerator(),
       RVector = rVector,
       GVector = gVector,
       BVector = bVector,
       BiasVector = biasVector
   };
   
   return colorMatrix.OutputImage;
   }
   

   public CIImage RandomGenerator()
   {
   var random = new CIRandomGenerator ();
   return Crop (random);
   }
   

3. Once we have the Sepia Tone and the white-specks images, we blend them using CISourceOverCompositing().

   var comp = new CISourceOverCompositing () {
   Image = ColorMatrix(),
   BackgroundImage = sep.OutputImage
   };
   

4. The final step is to render the filters into an image and display a preview on the image view.

   var output = comp.OutputImage;
   var context = CIContext.FromOptions(null);
   img.Dispose (); // clear image
   img = UIImage.FromImage (context.CreateCGImage (output, output.Extent));
   imageView.Image = img;