Creating avatar from uploaded image

We are using asp.net with .net 4.0

We want to allow users to upload any image and we want to create tiny avatar for uploaded image?

What is the best way to convert uploaded images for avatar?

• We want to keep the same height width ratio
• if we can convert gif, bmp, jpg, png to one s开发者_开发技巧tandard format it would be greate. Which could be the best format to convert it to? i think converting gif would be best option. am i correct?
• any open source option i can look at

You can use Gravatar.

To do it yourself, you can use System.Drawing.dll to create and resize a Bitmap object.