  The purpose of multi-focus image fusion is gathering the essential
information and the focused parts from the input multi-focus images into a
single image. These multi-focused images are captured with different depths of
focus of cameras. Multi-focus image fusion is very time-saving and appropriate
in discrete cosine transform (DCT) domain, especially when JPEG images are used
in visual sensor networks (VSN). The previous works in DCT domain have some
errors in selection of the suitable divided blocks according to their criterion
for measurement of the block contrast. In this paper, we used variance of
Laplacian (VOL) and energy of Laplacian (EOL) as criterion to measure the
contrast of image. Also in this paper, the EOL and VOL calculations directly in
DCT domain are prepared using vector processing. We developed four matrices
which calculate the Laplacian of block easily in DCT domain. Our works greatly
reduce error due to unsuitable block selection. The results of the proposed
algorithms are compared with the previous algorithms in order to demonstrate
the superiority of the output image quality in the proposed methods. The
several JPEG multi-focus images are used in experiments and their fused image
by our proposed methods and the other algorithms are compared with different
measurement criteria.
