A dual image technique is used as one of the data hiding
method. Dual image copies an image to two same images.
Through two images to embed or extract secret data, this
technique significantly enhances image quality. A dual
image technique is good or bad depending on the merits
of its algorithm. This paper proposes a method to improve
Lu et al. scheme. They use two pixels as a pair and
choose two same images to embed, and then choose both
two pixels to continue the procedure. We will depend
on circumstances of the second pixel pair after previous
embedding, and this case can increase the capacity. The
experiment results show that our proposed scheme is effective.
