چکیده (انگلیسی):

Purposely visual degradation of image quality is a newfangled
idea in the area of Histogram Association Mapped (HAM) reversible data
hiding. Such scheme first divides the color scale, i.e., 0-255, into some
partitions by the range, difference of minimum and maximum value of a
block. Next, the histogram of a block resided to a partition, original
partition, is moved, e.g., shifted, to another partition named reflective
partition. First, an association between the original and reflected partition
are defined by a chunk of secret message and then the translations of the
bins of the histogram of the original partition to the reflective partition are
performed to complete the message concealment. In such schemes, the
blocks are classified as Reflective Block (RB) and Non-Reflective Block
(NRB) based on whether the range is less than 127 or not. Experimentally,
it is observed that most of the RB blocks occupy the portion of two
partitions which introduce a dilemma in defining original partition as well
as associating and hence translating bins. Again, at NRB the range of
occupied bins in the histogram of a block is enough longer than the
available bins where to reflect. Therefore, the policy of associations and
then translations of bins of histogram may force the pixel values to exceed
the extremes of gray scale which is indeed impossible. Solutions to these
issues are not presented by any literature so far we have studied. Besides,
the side information database that is practiced to assist in decoding at
receiver is made longer by storing bundle of information and sometimes it
becomes near or more than both the secret data and size of image.
Resolutions to these stated observations are presented in this article.
Experimental results justify the necessity of mitigating these observations.