01-03-2013, 10:47 AM
Line-Based Cubism-Like Image—A New Type of Art Image and its Application to Lossless Data Hiding
Line-Based Cubism.pdf (Size: 2.17 MB / Downloads: 45)
Abstract
A new method of combining art image generation
and data hiding to enhance the camouflage effect for various
information-hiding applications is proposed. First, a new type of
computer art, called line-based Cubism-like image, which keeps
a characteristic of the Cubism art—abstraction by prominent
lines and regions from multiple viewpoints—is proposed. In the
creation process with an input source image, prominent line
segments in the image are detected and rearranged to form an
abstract region-type art image of the Cubism flavor. Data hiding
with the minimal distortion is carried out skillfully during the
process of recoloring the regions in the generated art image by
shifting the pixels’ colors for the minimum amount of 1 while
keeping the average colors of the regions unchanged. Based on
a rounding-off property in integer-valued color computation,
the proposed data hiding technique is proved by theorems to be
reversible, and thus useful for lossless recovery of the cover art
image from the stego-image. Four security enhancement measures
are also adopted to prevent hackers from extracting embedded
data correctly. Experimental results show the feasibility of the
proposed method.
INTRODUCTION
I N recent years, the topic of automatic art image creation via
the use of computers arouses interests of many people, and
many methods have been proposed [1]–[9]. Hertzmann [1] surveys
the ideas and algorithms of creating art images by strokebased
rendering which is an automatic approach to creating
nonphotorealistic imagery by the use of discrete elements like
paint strokes and stipples. The common goal of creating these
image styles is to make the generated art images look like some
other types of images. For example, two images created by watercolor
painting and oil painting in Hertzmann [2] and Hertzmann
[3], respectively, are shown in Fig. 1.
PROPOSED LINE-BASED CUBISM-LIKE IMAGE CREATION
PROCESS
Idea of Line-Based Cubism-Like Image Creation
Cubism artists transform a natural scene into geometric forms
in paintings by breaking up, analyzing, and reassembling objects
in the scene from multiple viewpoints. In addition, with
the scene objects rearranged to intersect at random angles, each
Cubism painting seems to be composed of intersecting lines and
fragmented regions in an abstract style. The idea of the proposed
art image creation technique is inspired by these concepts of the
Cubism art.
Specifically, there are two major stages in the proposed linebased
Cubism-like image generation process—prominent line
extraction and region recoloring. In the first stage, at first we
extract line segments from a given source image by edge detection
and the Hough transform. Then, we conduct short line
segment filtering and nearby line merging. In the second stage,
at first we create regions in the image by extending the line segments
to the image boundary to partition the image space. Then,
we recolor the regions by the average region colors and whiten
the boundaries of the regions.
Experimental Results
According to the above discussions, we see that different selections
of the two threshold values and will result
in totally different visual effects in the created art images. However,
it is difficult to decide which result is better than the others
because the decision is obviously dependent on people’s individual
feelings of art. Therefore, in this study we just offer a
series of results yielded by the use of different sets of values of
the two thresholds for the user to inspect and choose. Specifically,
we use the three values of 0.5/10, 1/10, and 2/10 times the
image width as the values for the thresholds and .
As a result, each threshold has three choices, resulting in nine
choices of the threshold pair.
Principle of Lossless Data Embedding
In the proposed region recoloring process, when embedding
a bit into a pixel with color , if is 0, then we decrement
by an integer value , and if is 1, then we increment by
. After hiding message bits into the pixels’ colors in a region
by color shifting in this way, the region’s average color will
also be changed. It is found in this study that the property of
rounding-off in integer computation may be utilized to modify
this region recoloring process to keep the average region color
unchanged, resulting in a reversible region recoloring process,
as proved in the following.
CONCLUSION
In this paper, a new method of combining art image generation
and data hiding to enhance the camouflage effect for
various information hiding applications is proposed. At first, a
new type of computer art, called line-based Cubism-like image,
and a technique to create it automatically from a source image
have been proposed.