Use Render Target Bitmap

   
  
<Window x:Class="BitmapProgramming.UseRenderTargetBitmap"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="BitmapProgramming" Height="300" Width="300">
  <Image x:Name="imageElement" />
</Window>

//File:Window.xaml.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace BitmapProgramming
{
    public partial class UseRenderTargetBitmap : System.Windows.Window
    {
        public UseRenderTargetBitmap()
        {
            InitializeComponent();
            RenderTargetBitmap bmp = new RenderTargetBitmap(
                300, 150,     // Dimensions in physical pixels
                300, 300,     // Pixel resolution (dpi)
                PixelFormats.Pbgra32);

            Ellipse e = new Ellipse();
            e.Fill = Brushes.Red;
            e.Measure(new Size(96, 48));
            e.Arrange(new Rect(0, 0, 96, 48));

            bmp.Render(e);
            imageElement.Source = bmp;
        }
    }
}