An image modification technique for assembling subpictures into a seamless picture is explored. The technique can be applied even when multiple subpictures of any shape and any size are overlapping with each other. To determine image modification functions, we introduce the concept of energy minimization which has been widely used for image processing and understanding. We use two kinds of energy: one represents the smoothness and the other represents the fitness of the image modification function. Image modification functions are defined so that the sum of those energies becomes minimum. Experimental results are shown to demonstrate the feasibility of the proposed method.