This paper presents a novel tone mapping method for a natural image hiding scheme using halftone images, where a
natural image can be visually decoded by overlaying two natural halftone images. In this scheme, there is a tradeoff
between noise and contrast, and a generally applicable setting of tone mapping before halftoning is required. However, in
a conventional method, the coefficients for the tone mapping cannot be found automatically. It is difficult even for
experts to manipulate the tradeoff with the coefficients. To solve this problem, we propose a deterministic tone mapping
method that can intuitively control the tradeoff. To realize this, we introduce a noise metric which can be understood
intuitively instead of affine parameters used in the mapping system. To maximize the dynamic range at a given noise
level and to make tone mapping deterministic, we clarify the condition and introduce the general functions to obtain
coefficients from the geometric constraint of the tone mapping region. The proposed method enables any user to generate
images with the highest possible contrast at a given noise level deterministically from any natural images such as own
photos just by setting the noise level. Experimental results show the validity of the proposed noise metric and also show
that the generally applicable tradeoff point through various images that are used as a guideline to set the noise level. By
using the tradeoff point, the average dynamic range is expanded by a factor of 1.4 compared to the noiseless case.
This paper presents a scheme which utilizes comments given to images on an image-sharing site in order to obtain an
appropriate image for insertion into poem-like weblogs (blogs) as a way to represent their atmosphere (impression). The
result shows that utilizing comments is effective. To achieve this purpose, there are two issues: how impression words
are extracted from blogs and how images representing the impression words are obtained. Assuming that it is important
to obtain images representing the impression words, this paper focuses on only the latter issue. We hypothesize that
comments and tags extracted from an image-sharing site can be adequate for obtaining images corresponding to
impression words at low cost. In particular, utilizing comments can be more appropriate for the image search with
impression words than utilizing tags because the impression words are often used in comments. Therefore, we propose a
scheme which utilizes comments to obtain appropriate images. In order to investigate the effectiveness of utilizing
comments, conformance between impression words and the images was evaluated. The rating for conformance is 3.5 on
a scale of 1 to 5 when utilizing comments, which is 0.6 higher than when utilizing tags.
FGS is a video coding scheme that can control picture quality with high scalability, but it has lower efficiency than the single layer video coding scheme because of its hierarchical structure. This paper proposes application scheme of three methods for efficiency improvement to the FGS encoder and decoder. The first method is the bit plane coding method using two bit group separation based on the distribution of a significant bit. The second method is the introduction of motion compensation estimation to the enhancement layer. The third method is a complement method to make a high quality reference picture from both the base layer and the enhancement layer. In conclusion, the proposed methods can improve the coding efficiency in the enhancement layer of conventional FGS by 2.2% and the PSNR performance of conventional FGS by 1.1dB, as well as reduce propagation of the drift error caused by low rate transmission and channel congestion. The results show that the proposed method is more efficient and more suitable for video streaming on a heterogeneous network with channel deviation.
This paper focuses on the encoder of ITU-T H.264 | ISO/IEC MPEG-4 Part-10 AVC (hereafter “JVT”), especially the Lagrange parameter for the rate distortion optimization (RDO) scheme. Since the Lagrange optimization method is very effective from the viewpoint of coding efficiency optimization, it is specified as an essential experimental condition for performance evaluation in JVT standardization activity. After discussing the background of this mechanism, we verify this method and the currently used parameter theoretically. Computer simulation results show that the Lagrange multiplier might not necessarily be original value; smaller values provide better performance in QCIF, for example.