RgbLevelsFilter Class

public ref class RgbLevelsFilter sealed : IFilter, 
	__IRgbLevelsFilterPublicNonVirtuals

using (var filterEffect = new FilterEffect(source))
{
    // Initialize the filter and add the filter to the FilterEffect collection
    var filter = new RgbLevelsFilter();

    var rgbLevels = new Levels() { Min = 0, MidTone = 1.25, Max = 255 };            
    var redLevels = new Levels() { Min = 0, MidTone = 1.0, Max = 255 };
    var greenLevels = new Levels() { Min = 0, MidTone = 1.0, Max = 243 };
    var blueLevels = new Levels() { Min = 0, MidTone = 1.0, Max = 202 };

    filter.Rgb = rgbLevels;
    filter.Red = redLevels;
    filter.Green = greenLevels;
    filter.Blue = blueLevels;

    filterEffect.Filters = new IFilter[] { filter };

    // Create a target where the filtered image will be rendered to
    var target = new WriteableBitmap(width, height);

    // Create a new renderer which outputs WriteableBitmaps
    using (var renderer = new WriteableBitmapRenderer(filterEffect, target))
    {
        // Render the image with the filter(s)
        await renderer.RenderAsync();

        // Set the output image to Image control as a source
        ImageControl.Source = target;
    }

    await SaveEffectAsync(filterEffect, "RgbLevelsFilter.jpg", outputImageSize);
}