I just had to have a go at this. I found it very difficult to come up with a convincing representation of a burnt image such as would be made with a branding iron (letters or logo).
The burnt imprint should appear beneath the surface. So it must have slight indents "walls" inside the print but there should not be a very big difference in colour as the walls are burnt almost black or very deep brown, as is the bottom . The differences in colour should be minimal yet convey a feeling of depth. At the top there will be minimal lateral burns in the grain of the wood. There will also be a slight discolouration around the shape as the heat burns sideways as well as downwards. And generally there will a larger area that will be discoloured from smoke and heat.
I tried to keep these criteria in mind but I am not that happy that I achieved what I wanted. Anyway here is my interpretation of a burned imprint.
![Image](http://www.gimpchat.com/files/221_.burned%20wood2.jpg)