Masayuki Iizuka

Quantitative evaluation of similar images with quasi-gray levels

Abstract The mutual relationships between the visual appearance of an image and its quantitative evaluation based on various statistical computation results have not been clear, regardless of a large number of recent research efforts. The purpose of this study is to determine the most effective measures from a set of proposed texture features. In this paper, two kinds of portrait images were displayed on a CRT device by a direct gray level transform method and a modified and constrained average method. The contrast between the visual appearance and the numerical values of texture features obtained from the co-occurrence matrix and that of the Erms and SNR in an image is brought out and discussed.

Transparency and colour shift of ray-traced images

Abstract Simple and practical colour-rendering techniques for depicting 3D transparent objects are studied by means of a 16-bit microcomputer system and a colour CRT with a resolution of 640 × 400 dots. In this computer system, an input/output type interface board called SuperFrame, i.e. 640 × 400 × 24 bit frame buffer is installed in a part of the extension slot. A complex of reflected scene with boundary surfaces may be simulated using solid geometry models composed of a few primitives. Transparency and colour shift of ray-traced images are discussed from the viewpoint of colour-rendering techniques.

Generation of quasi-fine colour images by random dither techniques and photographic multiple exposure techniques

Abstract It is possible to generate quasi-fine colour images without recourse to specialized computer graphics systems. Commercially available microcomputer systems with 16 bit CPU are used to simulate computer-generated images of 3-D objects based on a shading model. Quasi-fine colour images produced by random dither techniques for display of half-tone images, and by photographic multiple exposure techniques are demonstrated from the viewpoint of two kinds of programming techniques. Image, quality and visual appearance are discussed as a result of the superposition of red, green and blue primary colours.

Visual appearance and its fidelity evaluation of digital images displayed by means of orthogonal transform and adaptive spatial filter

Abstract The comparison between modified and/or compressed digital images and original digital images, i.e. reconstructed digital images, may be simply demonstrated by means of two-dimensional orthogonal transform techniques and adaptive spatial filters in the domain of the spatial frequency. The main purpose of this study is to examine how much the visual appearance of the reconstructed images is essentially affected by two types of parameters: the number of the threshold value and the value of the weighting coefficients necessary to the concept of an adaptive spatial filter, which is generally used in a small divided block domain in connection with simplified digital image compression techniques. Moreover, the suitability of 3D visualization and/or quasi-colour representation techniques is verified as a means for intuitively understanding the discriminating features of reconstructed images. To sum up, this study is executed to examine the contrast between the visual appearance of difference images and fidelity evaluation of image quality.

Psychophysical effect of retouched and modified digital stereograms for binocular vision on depth perception

A stereogram differs from the 3D picture often called stereo pair in appearance. There is no need of special viewer or glasses for stereopsis when viewing the sterograms. It is possible to intuitively carry out the intuitive estimation of depth perception by simultaneously viewing two pairs of stereograms which are arranged the upper and lower sides, or the right and left sides. In this study, modified digital color stereograms are directly viewed on the LCD screen or hard copy images by means of (a) crossing view method or (b) parallel view method. The apparent depth perception of stereograms can be effectively demonstrated by an adjustment of the viewing distance between the eye position of an observer and the plane of a stereogram rather than by altering the size and its arrangement of basic patterns which construct the plane images for steropsis. The visual effect of depth perception in the modified digital stereogram using sharpening filtering operation are discussed in connection with the modified various stereograms under the specified conditions: the number of pixel resolution and color bit levels.

Visual appearance effect on modified reconstruction color images of optical Fourier transform hologram by means of digital image processing

A blue white He-Cd laser composed of three R/G/B component beams in place of He-Ne laser is directly applied to fabricate the optical Fourier transform hologram (OFTH) using the red sensitive silver halide material (SO-253 film) for holography. As a result, the red beams play an important role as the coherent beams in the fabrication of OFTH. A green solid state laser is applied to fabricate the OFTH using the same film for holography. The visual appearance of reconstruted color images caused by He-Cd laser is discussed in contrast to that of an ordinary OFTH which can be made using the He-Ne laser and solid state laser. The visual color effect using the He-Cd laser is checked from the viewpoint of the relative real size and its place in the OFTH, and the visual depth sensation of overlapped ghost images called cross-talk in the Fresnel hologram. The purpose using a commercially available software such as HSL color model is to carry out the intuitive modification of overlapped and deteriorated color images in the digital reconstruction of OFTH and Fresnel hologram.

Evaluation and Analysis of Traditional Town Landscape by Computer Graphics: Influence on Surrounding Landscape by Vending Machines@@@自動販売機による景観への影響について

In recent years, it has been viewed that the color of advertising signboards or vending machines on streets should be harmonized with the surrounding landscape. In this study, we investigated how (red and white) vending machines virtually installed into a scene by using CG would affect a traditional landscape. In addition, we investigated the harmony of the vending machine with the surrounding landscape and compared different cases in which there was advertisements or nothing. Landscape Cc;s with without vending machines of Hida-Takayama and Hida-Furukawa were evaluated by 20 subjects by using SD techniques. The results of our experiments show that the vending machines have a great influence on the surrounding landscape. On the other hand, we confirmed that they could be harmonized with the landscape if the right colors were used for their paint scheme.

Cross-talk of reconstructed diffractive color images using He-Cd laser and dichroic mirror

A blue white beam of commercially available He-Cd laser is simply divided into the light with three primary colors, i.e., R/G/B components, using a set of dichroic mirrors. The dichroic mirror is widely used in color TV cameras or in optical special sensors to separate the visual image into its three primary color components. In this study influence on additive color mixture of two types of reconstructed hologram images is checked from the optical experimental results using the He-Cd laser and dichroic mirrors. The visual appearance and deterioration of reconstructed images owing to the cross-talk are discussed as for the optical Fresnel hologram and computer generated FTH. In the case of the Fresnel hologram, the reduction ratio, i.e., estimation value of reconstructed color images is considered from the theoretical and experimental view-points.

Achromatic or quasi-color Fourier transform hologram and optical diffraction images

A binary computer generated hologram (CGH) and a Fourier Transform hologram (FTH) with gray level/quasi-colors are similar to all appearance in the structure of hologram cell. However, they are wholly different in display techniques by the use of gray level or quasi-colors. It is possible to directly take a picture of reduced FTH, i.e., a kind of positive and negative transparency, displayed on a standard color LCD/CRT using a negative film with high contrast.

Similarity and fidelity of lossy images reconstructed by means of integer-based matrix algorithms for discrete Haar and wavelet transforms

Integer based-matrix algorithms for discrete Haar transform and discrete wavelet transform are proposed with relation to the multiresolution representation. A recursive wavelet transform technique is used with a view to demonstrating simply lossy reconstructed images in contrast to an original image under the specified resolution size. A visual effect of reconstructed images with different appearance and image quality, caused by modifying or throwing away a part of the 2D evaluation such as similarity and/or modified similarity, and fidelity: RMSE and/or PSNR.