I need to calculate water/gas percentage in a transparent porous media. I have three objects in my images, water, gas and the glass body (Figure 1-1). The problem I am having here is since the water is colorless and the glass of the cell is transparent that makes the recognetion between them very difficult. Therefore I injected dyed water through the cell to get an image with tow objects, pore (blue water) and the glass (Figure 2-1). Then I tryied to overlay Image 1 over 2. However the overlaying was not good. It looks like one image is croked or somehow the two images dont fit perfectly. Please if any one can help me to resolve this. If you can help me with image processing I will be happy to include you as a co-outher.