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.
KEYWORDS: 3D displays, 3D image processing, Mobile devices, Image quality, Visualization, 3D vision, Glasses, Large screens, Small screens, 3D visualizations
High-quality stereoscopic image content must be viewable in a variety of visual environments, from 3-D theaters to 3-D
mobile devices. Stereoscopic effects, however, are affected by screen size, viewing distance, and other parameters. In
this study, the authors focus on the stereoscopic image quality experience of viewing 3-D content on a mobile device in
order to compare it with that of viewing 3-D content on a large screen. The stereoscopic image quality experience was
evaluated using Interpretation Based Quality (IBQ) methodology, which combines existing approaches to image quality
evaluation, such as the paired comparison and interview, and assesses the viewer experience using both quantitative and
qualitative data. Five stereoscopic images were used in the experiment. The results of the experiment suggest that the
discomfort felt while viewing stereoscopic images on a 3-D mobile device arise from not only visual fatigue but also the
effects of the smaller screen size. The study also revealed the types of stereoscopic images that are suitable for viewing
on 3-D mobile devices.
The authors developed a software-based realtime IPTV monitoring system based on Reduced Reference framework, and evaluated the proposed system. One of the quality issues of the IPTV service is the picture quality degradation caused by packet loss. The proposed system precisely estimates the PSNR of the corrupted received picture by extracting and comparing image features from transmission and receiver side. Computer simulations show that PSNR estimation with a
0.945 correlation coefficient at a data channel bitrate of 36kbps is possible using the proposed system.
A method to estimate the PSNR of transmitted video quality based on the reduced reference method is proposed. We previously studied PSNR estimation using the image feature extraction method based on the spread spectrum and Walsh-Hadamard transform (WHT); however, the conventional method is problematic because large bandwidth is required for the transmission of image features. We therefore propose an improved method that reduces the information amount of the image features. The image feature is expressed by the parity of the quantized level of the WHT coefficients and requires only 1 bit for one image feature while the conventional method requires 8-11 bits for each image feature. Computer simulations show that precise picture quality evaluation is possible at one eighth as much bitrate of the data circuit as the conventional method.
Measures for coping with transmission errors in wireless environments are essential for mobile video communication. This paper proposes a “flat-scalable” scheme that has transmission error tolerance and is applicable regardless of the video compression method. The proposed scheme, which uses two sets of encoders and decoders, is a diversity method in the application layer. This scheme, by differentiating the temporal position of I-pictures between the two encoders, obtains two decoded pictures whose coding noises differ. When there is no error on
both streams, it averages the two decoded pictures to reduce noise and improve PSNR. When one of the streams has errors, it outputs the decoded picture without errors. This scheme greatly improves the received picture quality compared to the conventional single stream scheme especially when there are transmission errors.
A novel method of detecting local impairment of the coded picture caused by transmission failure on digital television transmission using a reduced reference framework is proposed. The method utilizes the SSSWHT method, which is based on spread spectrum and extraction of WHT coefficients, and precisely estimates the MSE in a small region within the frame using reduced references to detect local impairment caused by MPEG bitstream error. Computer simulations show that the proposed method detects the impaired frames completely at a reference path bitrate of 425 kbps. The method also detects slices that have impaired pixel blocks with accuracy of approximately 70% at a reference path bitrate of 425 kbps. These results confirm that the proposed method is effective for television transmission monitoring.
The rapid progress in digital transmission technology has spurred demand for developing a technology that supports monitoring of video transmissions. Automating the picture quality assessment process is in particular demand because it currently depends on subjective assessments by human operators and places a heavy burden on them. The authors therefore propose an objective picture quality measurement method that works without reference pictures. In this proposed method, invisible markers are embedded into original pictures by use of the spread spectrum data hiding method. Since the markers are widely spread over the frequency domain, the degradation caused by MPEG compression can be estimated by detecting the extent of marker degradation. Our method is usable regardless of the kind of picture, bitrate, and number of stages of tandem codec connections. The degradation in picture quality caused by the embedded markers is quite small and not perceivable by the human eye. The proposed method is therefore applicable to a wide range of visual transmission services.
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