<p>I want to scale an image in C# with quality level as good as Photoshop does. Is there any C# image processing library available to do this thing?</p>

When you draw the image using GDI+ it scales quite well in my opinion. You can use this to create a scaled image.
If you want to scale your image with GDI+ you can do something like this:
```
```
Bitmap original = ...
Bitmap scaled = new Bitmap(new Size(original.Width * 4, original.Height * 4));
using (Graphics graphics = Graphics.FromImage(scaled)) {
  graphics.DrawImage(original, new Rectangle(0, 0, scaled.Width, scaled.Height));
}
```
```