Masashi Kameda

Image reconstruction from compressed encrypted digital hologram

This paper is a revision of a paper presented at the SPIE conference on Algorithms and Systems for Optical Processing V, Jul. 2001, San Diego, California. The paper presented there appears (unrefereed) in SPIE Proceedings Vol. 4471. An encrypted digital holographic data reconstruction method with data compression is proposed. We show that the number of quantization levels of the digital hologram can be reduced. By computer simulations, we confirm that the method is especially useful for binary images. For gray-scale images, we propose a bit plane decomposition method. By this method, we show that both high reconstructed image quality and a high compression ratio can be achieved.

Digital holographic data reconstruction with data compression

A digital holographic data reconstruction method with data compression is proposed. We show the number of quantization level of a digital hologram can be reduced. By computer simulations it is confirmed that the method is especially useful for binary images. For gray scale images, we propose a bit plane decomposition method. By this method, we show both high reconstructed image quality and a high compression ratio can be achieved. This method is applicable to both a normal digital hologram and an encrypted digital hologram.

Objective picture quality scale for video images (PQSvideo): definition of distortion factors

We propose a PQSvideo (Picture Quality Scale for moving image), a method of objective quality assessment for coded moving images. We expect that the proposed PQSvideo approximates subjective assessment well. In PQSvideo, we define essential distortion factors considering not only global distortions (such as random noise) but also distortions on local features. Then, we describe each distortion metrically considering human visual perception. The PQSvideo is given by a linear combination of define each essential distortion factor, utilizing the principal component analysis method and the multiple regression analysis method between quantity of each essential distortion factor and MOS (Mean Opinion Score) obtained by assessment test. We have confirmed that the PQSvideo approximates MOS successfully.

Corresponding affect between music and color

We propose a new method to realize the media conversion between music and image according to the feeling. In this research, we have focused on color combination and corresponded the affect evoked from music with color combination in subjective assessment. As the result, the affective mapping table between music and color combination has been obtained and the reliability of the obtained mapping table has been verified in the viewpoint of media conversion. The selected color combinations based on the mapping table evoke the affect like the musical affect: the maximum concordance rate between music and color combination is 70%. In this research, it is clarified that (1) musical affect and color affect have strong similarity each other, and (2) color combination can be applied to the sophisticated media conversion between music and image.

Computer-assisted identification of the central sulcus in patients with brain tumors using MRI

To develop computer‐assisted image processing to identify the central sulcus from the MRI data sets in patients with brain tumors.

Single image super-resolution based on total variation regularization with Gaussian noise

The single image super-resolution to improve the image quality the texture in magnified image has been proposed. Our method uses a given low-resolution image only to generate high-resolution image, it cannot use extra high-resolution images. The single image super-resolution can improve the edge of image quality in magnified image. However, improvement of texture of sharpness in magnified image is difficult to generate high frequency components using only given input image. We propose single image super-resolution to improve texture of sharpness in magnified image by additional components of Gaussian noise. We can success to generate new higher frequency components by using Gaussian noise. Moreover, we propose assessment measure of image quality for super-resolution. In our experimental results, texture in magnified image by our proposed method is improved compared with other super-resolution methods.

The optimum space-frequency partition for subband image coding in a rate-distortion sense

Subband coding is a powerful means for highly efficient image signal compression. We have proposed the optimum frequency band partition (OFBP) to improve the compression performance of subband image coding. OFBP determines an adaptive partition pattern on the 2-dimentional frequency domain considering the characteristics of an input image under the condition of a small number of subbands. However, the OFBP cannot obtain the optimum partition pattern in terms of rate-distortion sense for image compression. This is caused by the partition pattern being fixed, even if the desired bit rate changes. This paper presents an optimum space-frequency partition (OSFP) as a new OFBP. The optimized factors include the band partition on the 2-dimentional frequency domain, the combination of quantizers within subbands and the pruning of coefficient nodes in each subband (also referred to as the spatial domain partition), are optimized in terms of rate-distortion sense in case of an arbitrary given bit rate budget. Experimental results show the outperformance of several conventional image compression methods by the proposed OSFP coder.

Development of an algorithm for media conversion between music and color combination based on impressions

We propose a new method to realize a media conversion between music and color combination based on impressions. In order to synchronize color combination with music, we focus on time-series changing of musical impressions. Our proposed method divides an input music into some subsequences and a color combination is assigned to each subsequence. In the subjective assessment, the impressions for each sub-sequence are evaluated, and we develop an algorithm to derive the most appropriate color combination to the impressions of each sub-sequence. From the experimental results using five musical sources, the average of concordance rate between music and the derived color combinations in our algorithm is about 83%. In this research, it is clarified that the degree of impressional similarity between music and color combination in media conversion is improved by our algorithm considering the time-series changing of musical impressions.

A new metric for definition of gaze area from the geometrical structures of picture composition

When a human observes any picture, the gaze area which is changed in time by time is defined as dynamic gaze flow. The dynamic gaze flow is used in picture cording, image evaluation and computer vision effectively. On the other hand, the technique with composition is known well the photograph and fine arts. Composition is effective to attract the human attention in some specific area. We propose a new method to analyze scanpath of the dynamic gaze flow based on image analysis. Our proposed method analyzes the composition of input image as the primary factor of gazing, and the obtained dynamic gaze flow is evaluated by comparing with the scanpath of observers which is measured with eye-mark recorder.

Optimum partition of two-dimensional frequency band with human visual sensitivity for subband image coding

This paper proposes a method of optimizing the partition of a two-dimensional frequency band so that high-quality reconstructed images are obtained by subband image coding. This partitioning is derived by minimizing the weighted quantization noise power with human visual sensitivity. To simplify the coding system, the structure of the filter bank is analyzed. The band partition parameters which makes the filter bank more efficient are selected, based on experimental results for actual images. The quality of images reconstructed by the proposed method is evaluated by using the relationship between the weighted quantized noise power and their entropy. The proposed method is subjectively evaluated by comparing it with a nonweighted method and the DCT method.