System.Drawing.Icon

Language	C# (.NET Framework, .NET on Windows)
License	MIT
Repository	github.com/dotnet/winforms (System.Drawing.Common)
Documentation	Icon class
Depends on	Windows (GDI+, user32); `System.Drawing.Common` NuGet package on .NET 6 and later
Read / write	yes / no new icons (`Save` writes back the loaded icon data)

System.Drawing.Icon wraps a Windows icon handle. Its constructors take a desired size and pick the best matching entry from an ICO file, the way Windows does. ToBitmap converts the selected entry to a 32-bit Bitmap with alpha, which you can save as PNG. Icon.ExtractAssociatedIcon and Icon.ExtractIcon get icons out of EXE, DLL and other files.

It’s Windows only: since .NET 6, System.Drawing.Common throws PlatformNotSupportedException on Linux and macOS. It can’t create a multi-size ICO file; use Magick.NET or ImageSharp for that.

Installation#

Windows Forms and WPF projects already reference it. In other .NET projects:

Shell

dotnet add package System.Drawing.Common

Basic usage: load a size and save it as PNG#

using System.Drawing;
using System.Drawing.Imaging;

// picks the entry closest to 48x48
using var icon = new Icon("app.ico", 48, 48);
Console.WriteLine($"selected entry: {icon.Width} x {icon.Height}");

using Bitmap bmp = icon.ToBitmap();
bmp.Save("app-48.png", ImageFormat.Png);

How to get the largest icon in an ICO file#

Ask for a size larger than any entry; the constructor returns the closest one:

using var icon = new Icon("app.ico", 256, 256);
using Bitmap bmp = icon.ToBitmap();
bmp.Save("app.png", ImageFormat.Png);

How to extract the icon of an EXE or DLL#

using System.Drawing;
using System.Drawing.Imaging;

// the icon Explorer shows for the file
using Icon? shown = Icon.ExtractAssociatedIcon(@"C:\Windows\notepad.exe");

// icon number 0 at 256x256 (.NET 8 and later)
using Icon? large = Icon.ExtractIcon(@"C:\Windows\System32\shell32.dll", 0, 256);
large?.ToBitmap().Save("shell32-0.png", ImageFormat.Png);

How to load an icon from a stream#

using var stream = File.OpenRead("favicon.ico");
using var icon = new Icon(stream, new Size(32, 32));

Tips#

Bitmap.Save(path, ImageFormat.Icon) doesn’t write an ICO: GDI+ has no ICO encoder and writes PNG data. Use another library to create icons.
Icon.Save(stream) writes the original file data of the loaded icon, all entries included.