I have looked around quite a bit for an easy way of adding copyright text into images for the various websites I have made. I looked into ImageMagick, which seems to be the most powerful and flexible commandline tool available for doing this, however here is a very simple c# snippet for accomplishing the same result.
Bitmap bmp= new Bitmap("myimage.jpg");
Graphics g=Graphics.FromImage(bmp);
g.SmoothingMode = SmoothingMode.AntiAlias ;
g.DrawString("copyright kisomnu", new Font("verdana",12),SystemBrushes.WindowText, 1, 1);
Response.ContentType="image/jpeg";
bmp.Save( ... )
The main advantage of imageMagick is the powerful set of options to embed the text, it is harder to achieve this in c#, the main drawback is that if the rest of our code is in c#, we need to make an external call and we furthermore generate a dependency on anexternal tool. This can be problematic especially when we frequently upload galleries.
Another advantage is that imagemagick can not be run on the server side in a web application (in most cases we won't have permission for this, unless we are hosting ourselves and can grant the required permissions.)