Removing shadows from white clear surface

Question

I have an image of an object taken in a studio. The image is well lighten from multiple sources and stands on a mate white background. the background is also lighten.

Most of the shadows that fall on the background are eliminated by the lights but there are still very little light shadows that I would like to remove.

Until now, the only solutions I found involved in manual intervention. I would like to know if there are known methods for this or if anybody has an idea how to approach such a problem.

The object can also contain white elements and at this point I can't change the background color (to green or blue).

Thanks.

Answer 1

If you have strong contrast between foreground and background you could use a simple floodfill algorithm that stops on hitting a large contrast difference to classify pixels as background and foreground. Then just adjust levels of background to saturate shadows to white while retaining somewhat reasonable edge quality. It helps if your input data is significantly higher resolution than the output. If you have soft edges or just need really good edge quality you'll need to employ an algorithm that for each edge pixel estimates background color, foreground color and transparency. A good approach is the Soft Scissors paper from SIGGRAPH 2007.