.NET - Resizing an image

Here's a little piece of C# code that resizes an image of any common type.
It was tested for .jpg, .png, .bmp and .gif.

using System.Drawing;
using System.Drawing.Drawing2D;
...
Image image = Image.FromFile(filePath);
if (image.Width > App.MAX_UPLOAD_IMAGE_SIZE ||
    image.Height > App.MAX_UPLOAD_IMAGE_SIZE) {
  int w = image.Width;
  int h = image.Height;
  if (w > h) {
    w = App.MAX_UPLOAD_IMAGE_SIZE;
    h = image.Height * w / image.Width;
  }
  else {
    w = image.Width * h / image.Height;
    h = App.MAX_UPLOAD_IMAGE_SIZE;
  }
  Bitmap bitmap = new Bitmap(w, h);
  Graphics g = Graphics.FromImage((Image)bitmap);
  g.InterpolationMode = InterpolationMode.HighQualityBilinear;
  g.DrawImage(image, 0, 0, w, h);
  g.Dispose();
  image.Dispose();
  (bitmap as Image).Save(filePath);
}

XAML - Makes the tab headers justify on the width of the whole tab control

Take a TabControl with a row of headers on top.
How do you make those headers justify so that together they have (more or less) the same width as the control?
Like this:

The converter

You need a converter to calculate the width a TabItem should have:

public class TabJustifyConverter : IValueConverter {
  public object Convert(object value,
                        Type targetType,
                        object parameter,
                        CultureInfo culture) {
    if (value == null) {
      return 0;
    }
    else if (!(value is TabControl)) {
      throw new Exception(@"The TabJustifyConverter must
                            be supplied a TabControl.");
    }
    else {
      TabControl tab = value as TabControl;
      int count = 0;
      foreach (TabItem item in tab.Items)
        if (item.Visibility == Visibility.Visible)
          count++;
      return (tab.ActualWidth / count) - 2;
    }
  }

  public object ConvertBack(object value,
                            Type targetType,
                            object parameter,
                            CultureInfo culture) {
    throw new NotImplementedException();
  }
}

The XAML

In XAML, give the TabControl a name.
Then bind each TabItem's width to this control and use the converter:

<controls:TabItem x:Name="tabCustomer"
          Header="Customer"
          Width="{Binding ElementName=tabControl,
                          Converter={StaticResource TabJustifyConverter}}">

I tried putting that in a resource, but kept getting a "cannot set read-only property"-exception.