  In most steganographic methods, increasing in the capacity leads to decrease
in the quality of the stego-image, so in this paper, we propose to combine two
existing techniques, Pixel value differencing and Gray Level Modification, to
come up with a hybrid steganography scheme which can hide more information
without having to compromise much on the quality of the stego-image.
Experimental results demonstrate that the proposed approach has larger capacity
while its results are imperceptible. In comparison with original PVD method
criterion of the quality is declined by 2% dB averagely while the capacity is
increased around 25%.
