// Create a CISmoothLinearGradient filter with the input image
var point0 = new CIVector(0, 0); // Default [0 0]
var point1 = new CIVector(250, 250); // Default [200 200]
var smoothLinear_gradient = new CISmoothLinearGradient()
{
	Point0 = point0,
	Point1 = point1,
	Color0 = new CIColor (UIColor.Red),
	Color1 = new CIColor (UIColor.Blue)
};

// Get the altered image from the filter
var output = new CICrop {
	Image = smoothLinear_gradient.OutputImage,
	Rectangle = new CIVector (0, 0, 400, 300)
}.OutputImage;

// To render the results, we need to create a context, and then
// use one of the context rendering APIs, in this case, we render the
// result into a CoreGraphics image, which is merely a useful representation
//
var context = CIContext.FromOptions (null);

var cgimage = context.CreateCGImage (output, output.Extent);

// The above cgimage can be added to a screen view, for example, this
// would add it to a UIImageView on the screen:
myImageView.Image = UIImage.FromImage (cgimage);