森本 雅和

To inspect medical capsules with one-dose package (ODP), we propose an automated inspection system based on computer vision. In the proposed system, we capture both-side of capsules at once and apply hierarchical recognition. In this paper, we report several results of preliminary experiments, which distinguish 9 kinds of capsules. As a result, we have achieved 99.1 percent recognition rate and discuss its validity.

To encourage drivers to keep their safety driving, it's effective to analyze their in-vehicle video sequences objectively. In this paper, we propose an evaluation method of driving behavior by using computer vision techniques. Here we use road-markings to estimate road environment and vehicle speed. When the car approaches pedestrian crosswalk or stop sign, the driver should reduce the vehicle speed carefully. By several evaluating experiments, we verify and discuss effectiveness of our method.

To inspect prescription drugs with one-dose package (ODP), we propose an automated inspection system which based on computer vision. In the proposed system, we capture both-side of drugs at once and apply hierarchical identification. In this paper, we report several results of inspection experiments, which distinguish about a hundred kinds of naked drugs. As a result, we have achieved sufficient recognition rate and discuss its robustness.

In this paper, we propose a method capable of shortening the distance from a noise detection microphone to a loudspeaker, which is one of important issues in the field of active noise control (ANC). In the ANC system, the secondary noise provided by the loudspeaker is required arriving at an error microphone simultaneously with the primary noise to be cancelled. However, the reverberation involved in the secondary path from the loudspeaker to the error microphone increases the secondary noise components arriving later than the primary noise. The late components are not only invalid for canceling the primary noise but also impede the cancellation. To reduce the late components, the distance between the noise detection microphone and the loud speaker is generally extended. The proposed method differently reduces the late components by forming the noise control filter, which produces the secondary noise, with the cascade connection of a non-recursive and a recessive filters. The distance can be thus shortened. On the other hand, the recursive filter is required to work stably. The proposed method guarantees the stable work by forming the recursive filter with the lattice filter whose coefficients are restricted to less than unity.

In this paper, we propose a step size control method capable of quickly canceling acoustic echo even when double talk continues from echo path change. This method controls the step size by substituting the difference between the coefficients of a main adaptive filter (Main-ADF) and a sub-adaptive filter (Sub-ADF) for the estimation error in the former. Actually, the number of taps of Sub-ADF is limited to a quarter of that of Main-ADF, and moreover another simplified step size control is applied to Sub-ADF accordingly the difference quickly approximates the estimation error. The estimation speed can be improved by utilizing the difference for the step size control. We show using speech signals that in single talk the proposed method can provide almost the same estimation speed as the method whose step size is fixed at the optimum one and verify that even in double talk the estimation error quickly decreases. © 2011 IEEE.

To inspect drug tablets with one-dose package (ODP), we propose an automated inspection system which based on computer vision. In the proposed system, we capture both-side of tablets at once and apply hierarchical identification. In this paper, we repot several results of preliminary experiments, which distinguish 100 kinds of naked tablets. As a result, we have achieved hundred-percent recognition rate and discuss its robustness.

In an inspection of a yarn-dyed-fabric, checking warp yarn arrangement is important. The warp is yarn that is attached to either beam on the loom (length-wise), therefore, miss-arrangement of warp yarn causes rejection of whole weaved fabric. In many textile factory, the warp inspection of trial weaving is usually done by skilled worker's eye. It is heavy task and undetected error causes a heavy loss to the factory. So, automated and reliable inspection by computer vision is required. To realise automated appearance inspection, deformation of fabric comes to an issue. To overcome this problem, we employ autocorrelation images. It makes yarn cycle detection easy, so we can achieve accurate warp arrangements from trial fabric. © 2010 TSI Press.

In this paper, we verify the performance of multiple-channel active noise control systems using the simultaneous equations method. This method has the advantage that it can automatically recover the noise reduction effect degraded by acoustic path changes. The method is hence applied to single-channel systems, and also it is shown that the method results in better performances than the filtered-x algorithm. In this paper, we extend the method to multiple-channel active noise control systems and verify the performance of the extended method by using impulse responses measured with an experimental system. The extended method is applied to a 1-2-2 system, consisting of one noise detection microphone, two loudspeakers and two error microphones, and to a 2-2-2 system including two noise detection microphones, resulting in noise reductions of 14 and 18 dB, respectively. This result demonstrates that the simultaneous equations method well works also for multiple-channel systems. © 2010 The Acoustical Society of Japan.

In this paper, we propose a method capable of shortening the distance from a noise detection microphone to an error microphone, called primary path in the field of active noise control (ANC). In the ANC system, the secondary noise provided by a loudspeaker is required arriving at the error microphone simultaneously with the primary noise to be cancelled. However, the reverberation involved in the secondary path from the loudspeaker to the error microphone increases the secondary noise components arriving later than the primary noise. The late components are not only invalid for canceling the primary noise but also impede the cancellation. The proposed method reduces the late components by forming the noise control filter, which produces the secondary noise, with the cascade connection of a non-recursive and a recursive filters. The distance can be thereby shortened. The problem is that it is difficult to guarantee the stable performance to the recursive filter. We solve the problem by forming the recursive filter with the lattice filter whose coefficients are restricted to less than unity. We have already proposed an adaptive algorithm for estimating the reflection coefficients, which can be applied to the estimation in the proposed method. In this study, the simultaneous equation method is used for the derivation of the cascade connection, and thereby the noise reduction effect degraded by path changes can be automatically recovered. We finally verify the performance of the proposed method by using computer simulations. According the simulation results, the distance from the noise detection microphone to the error microphone can be reduced to zero when the secondary path satisfies the minimum phase condition.

In this paper, we focus on a defect detection of a metal artifact which has cylinder shape and hair-line finished surface. It sometimes ruined by scratch and/or liquid spill in factory line. So we have to find them from line CCD scanned images. In this paper, we employ Support Vector Machines (SVM) as classifier and test several transformations of input images to set input vector. We also discuss tradeoff between detection accuracy and computation time. © 2009 TSI® Press Printed in the USA.

This paper proposes a method for shortening the distance from a noise detection microphone to a loudspeaker forming the feedforward type of active noise control (ANC) system. In the ANC system, the primary noise detected by the noise detection microphone and the secondary noise provided by the loudspeaker is required simultaneously arriving at another microphone, called error microphone, monitoring the effect of the active noise control. However, the reverberation involved in the secondary path from the loudspeaker to the error microphone increase the secondary noise components arriving later than the primary noise. The late components are not only invalid for cancelling the primary noise but also impede the cancellation. This paper hence proposes a method reducing the components by forming the noise control filter synthesizing the secondary noise with the cascade connection of an infinite and a finite impulse response filters. The distance can be thereby shortened. ©2009 IEEE.

This paper proposes a method for shortening the distance from a noise detection microphone to a loudspeaker forming the feedforward type of active noise control (ANC) system. In the ANC system, the primary noise detected by the noise detection microphone and the secondary noise provided by the loudspeaker is required simultaneously arriving at another microphone, called error microphone, monitoring the effect of the active noise control. However, the reverberation involved in the secondary path from the loudspeaker to the error microphone increase the secondary noise components arriving later than the primary noise. The late components are not only invalid for cancelling the primary noise but also impede the cancellation. This paper hence proposes a method reducing the components by forming the noise control filter synthesizing the secondary noise with the cascade connection of an infinite and a finite impulse response filters. The distance can be thereby shortened.

By specularity (clearness of mirror reflection) of mirror-finished object, we can estimate surface roughness of the polished object. There are several methods to evaluate specularity, but they have to contact a probe to object's surface and they spoil the evaluated products. Therefore, contactless specularity measuring system has been required. To develop the contactless system, we have to measure object position as preliminary steps. However, there are several difficulties to detect object position due to the mirror-reflection. In this paper, we propose a position detection method of mirror-finished object using Depth from Focus (DFF) procedure by monocular camera and striped pattern projection. From some experimental results, we can obtain the distance with error within several millimeters.

In this paper, we propose a facial direction estimating system from low resolution facial images captured by surveillance camera. The proposed system first detects pedestrians by background subtraction, then trimming head area by template matching and finally estimating facial direction by using support vector machine (SVM). Experimental results show that, when we use 8x9 pixels facial images as input, training image resolution and estimation image resolution are 8x9 and estimation directions are in 13 directions by the face databases, the estimation rates are more than 90% by our method.

In this paper, we focus on a defect detection of a metal artifact, which has cylinder shape and hair-line finished surface, and it is sometimes ruined by scratch and/or liquid spill in factory line. So we have to find them from line CCD scanned images. In this paper, we employ Support Vector Machines (SVM) as classifier and test several transformations of input images to set input vector. We also discuss tradeoff between detection accuracy and computation time.

In this paper, we propose a new method for detecting and extracting moving objects from moving stereo camera. Our purpose is not only detecting objects but also extracting shapes and colors of detected moving objects from stereo video streams. First, we estimate the camera motion from three-dimensional optical flow based on RANSAC. Secondly we detect moving objects from the scene by inter-frame subtraction. Then we extract the contour of the moving object based on intensity edge, disparity map and inter-frame subtraction. Finally we carry out some experiments and show some results. From results, we can detect and extract the moving object.

A phase-shifting method by the SLM has been proposed for simultaneous recording of phase-shifted RGB holograms. The phase of RGB lights can continuously be shifted by adopting a LCD panel. A system with a high-resolution reflective LCD panel, a color CCD, and red, green, and blue lasers is developed for recording 3D color images. The phase of RGB reference lights is precisely shifted by moving the diffraction grating on a reflective LCD panel. Since a shifted value of the phase is independent of the wavelength of light in the present method, RGB interference fringe patterns for the practical object can be recorded at once by adopting a high-resolution color CCD. Fine complex-amplitude holograms for reconstruction of RGB images are obtained from recorded interference fringe patterns, and high-quality color images of the practical object are reconstructed from the holograms.

In this paper, we propose a flexible gaze detection method using single PTZ (Pan-Tilt-Zoom) camera. In this method, a PTZ camera traces user's face and measures position of their viewing point, so they do not need to fix their head in front of camera. Furthermore, to realize accurate gaze detection, we employ elliptical iris template matching. To reduce calculation amount of iris template matching, we get rough gaze direction by simple method on ahead to decide ellipse shape. In this paper, we also adapt to variation of facial orientations, which will affect to detect viewing position and gaze direction. After several experiments, we examine accuracy of gaze detection and head tracking ability of this system.

The superimposing method is described in order to reduce information in hologram. This method improves loss of resolution and increase of the speckle noise which are caused by the information reduction in the sampling method. Experiments are carried out for reconstruction of images from the computer-generated hologram or from the practical hologram. Results show that high-resolution images with low speckle noise are reconstructed from the continuous periodic hologram with reduced information. The image without visual depth is reconstructed on the Fourier transform plane from the hologram with reduced information, if the bandwidth is taken to be smaller than the diameter of observer's pupil. The visual field is divided into several fields in order to display images with visual depth, and images in divided fields are recorded on several Fourier transform holograms. A time-sharing system with a movable reference light source is developed in order to reconstruct real-time 3D images from several Fourier transform holograms with reduced information.

A time-sharing holographic color display system is developed using a high-resolution reflective liquid-crystal display (LCD) panel that consists of a 1920×1080 array of square pixels with width of 8.1 micron. Red, green and blue images with high resolution are reconstructed from the holographic display system with a low-power red laser diode (LD), a low-power green diode-pumped laser and a low-power blue diode-pumped laser. The reconstructed color image can clearly be observed under the room light. The image exhibits good color expression. Moving 3D color images with high quality are reconstructed from holograms displayed on the LCD panel of the developed holographic system.

A phase-shifting holography system for recording 3D color images is developed with a color CCD, and red (R), green (G), and blue (B) lasers. Phase of reference lights in this recording system is precisely shifted by shifting fringe patterns displayed on a high-resolution reflective LCD panel. Color images of the practical object are able to be recorded at the same time as RGB interference fringe patterns by adopting a high-resolution color CCD. Holograms for reconstruction of fine RGB images are obtained from recorded fringe patterns by the phase-shifting holography, and animated high-quality color images of the practical object are reconstructed from the holograms using the developed holographic color display system.

A time-sharing holographic color display system is developed using a high-resolution reflective liquid-crystal display (LCD) panel that consists of a 1920 x 1080 array of square pixels with the pixel pitch of 8.1 micron. Red, green and blue high-resolution images are reconstructed from the holographic display system with a red laser diode (LCD), a green diode-pumped laser and a blue diode-pumped laser. The reconstructed color image can clearly be observed under the room light. The image exhibits a large color gamut good color expression. High-quality color images of the practical object are reconstructed from recorded holograms by using the developed holographic display system. The viewing zone or the visual field of the holographic display is enlarged by adopting a multi-channel LCD modulator. The viewing zone angle or the visual field angle of color images is enlarged up to about 20 degrees by adopting a 6-channel LCD modulator.

The superimposing method for information reduction in hologram is compared with the sampling method to clarify their features. 3D images with motion parallax are reproduced in the wide viewing zone from holograms with reduced information. The visual field is divided in several fields for displaying visual depth of the image under reduced information, and partial images in divided visual fields are separately recorded on several Fourier transform holograms (FTHs). A time-sharing display system is developed to reconstruct the 3D image in real time from several FTHs. Experiments are carried out for reconstruction of the practical 3D image from recorded holograms. Results show that resolution of the image is improved, and the speckle noise is suppressed by the superimposing method. Observer can perceive motion parallax of the image with wide viewing zone by viewing a pair of stereoscopic images from right-eye and left-eye positions. Observer can also perceive the correct visual depth of images through a parallax-fusing perceptual phenomenon.

A phase-shifting holographic system for recording 31) color images is developed with a color CCD, and red (R), green (G), and blue (B) lasers. The phase of reference lights in this recording system is precisely shifted by moving the diffraction grating displayed on a high-resolution reflective LCD panel. Measurement of the phase shift of the diffracted light demonstrates the feasibility of the phase-shifting method. RGB in-line holograms can be recorded at the same time for a practical color object by adopting a high-resolution color CCD. Color images in the wide visual field are recorded by adopting a multi-channel CCD and are reconstructed from the recorded hologram by adopting a multi-channel LCD modulator. Holograms for reconstruction of RGB images are obtained from recorded in-line holograms by the phase-shifting holography, and fine color images of high quality are reconstructed from recorded phase-shifting holograms. The visual field or the viewing zone of the holographic system is enlarged by adopting a multi-channel color CCD and a multi-channel LCD panel.

To reconstruct the 3D model of a large structure, multiple measurement from various angle are required. In this paper, we propose a portable 3D scanner system which combines narrow-baseline stereo camera and consumer video projector. In proposed system, we can settle camera and projector in arbitrary position and angle. The relative position of camera and projector is automatically calibrated from image sequences. The proposed system realizes high measuring flexibility, because stereo camera and projector do not need to be fixed. © 2005 IEEE.

A phase-shifting holography system for recording 3D color images is developed with a color CCD, and red (R), green (G), and blue (B) lasers. The phase of reference lights in this recording system is precisely shifted by changing fringe patterns displayed on a high-resolution reflective LCD panel. RGB interference fringe patterns are able to be recorded at the same time for a practical color object by adopting a high-resolution color CCD. Color images in the wide visual field are recorded by adopting a multi-channel CCD and are reconstructed from the recorded hologram by adopting a multi-channel LCD modulator. Holograms for reconstruction of RGB images are obtained from recorded fringe patterns by the phase-shifting holography, and fine color images with high quality are reconstructed from recorded phase-shifting holograms by using the developed holographic color display system. The visual field of the holographic system is enlarged by adopting a multi-channel color CCD for recording of the image and a multi-channel LCD panel for reconstruction of the image.

The superimposing method for information reduction in hologram is compared with the sampling method to clarify their features. Visual field is divided in several fields for displaying visual depth of the image under reduced information, and partial images in divided visual fields are separately recorded on several Fourier transform holograms (FTHs). A time-sharing display system is developed to reconstruct the 3D image in real time from several FTHs. The 3D image with motion parallax is reproduced in the wide viewing zone from holograms with reduced information by reconstructing overlapped two images. Experiments are carried out for reconstruction of the practical 3D image from recorded holograms. Results show that resolution of the image is improved and the speckle noise is suppressed by the superimposing method. Depth of the 3D image can be perceived by viewing partial images reconstructed on Fourier transform planes. Observer can perceive motion parallax of the image by viewing a pair of overlapped stereoscopic images from right-eye and left-eye positions.

A time-sharing holographic color display system is developed using a high-resolution reflective liquid-crystal display (LCD) panel that consists of a 1920×1080 array of square pixels with width of 8.1 micron. Red, green and blue high-resolution images are reconstructed from the holographic display system with a red laser diode (LCD), a green diode-pumped laser and a blue diode-pumped laser. The reconstructed color images can clearly be observed under the room light. The images exhibit good color expression. High-quality color images of the practical object are reconstructed from the holograms by using the developed holographic display system. The viewing zone or the visual field of the holographic display is enlarged by adopting a multi-channel LCD modulator. 3-D full-color images are reconstructed in the wide visual field. Viewing zone angle or visual field angle of color images can be enlarged up to about 20 degrees by adopting a 6-channel LCD modulator.

The superimposing method is described in order to reduce information in hologram. This method improves loss of resolution and increase of the speckle noise due to the information reduction as compared with the sampling method. Experiments are carried out for reconstruction of images from the computer-generated hologram or from the practical hologram. Results show that high-resolution images with low speckle noise are reconstructed from the continuous periodic hologram with reduced information. The image having no parallax is reconstructed on the Fourier transform plane from the hologram with reduced information, if the bandwidth is taken to be smaller than the diameter of observer's pupil. A time-sharing system is developed in order to display real-time 3D images with full parallax using several Fourier transform holograms with reduced information.

A time-sharing holographic color display system is developed using a high-resolution reflective liquid-crystal display (LCD) panel that consists of a 1920×1080 array of square pixels with width of 8.1 micron. Red, green and blue images with high resolution are reconstructed from the holographic display system with a red laser diode (LD), a green diode-pumped laser and a blue diode-pumped laser. The reconstructed color image can clearly be observed under the room light. The images exhibit good color expression. A phase-shifting holography system is also developed in order to record 3D color images, where phase of the reference light is shifted by changing fringe patterns displayed on the reflective LCD. Color image of the practical object are recorded as RGB fringe patterns by adopting a high-resolution color CCD. Clear RGB holograms are obtained from recorded fringe patterns by the phase-shifting method, and moving color images with high quality are reconstructed from the holograms by using the developed holographic display system.

Object segmentation based on the joint use of depth and color data produces superior results than can be achieved with either data source alone. Conventional object segmentation methods using depth data give priority to processing speed. So the shape accuracy is not enough to use object-based video coding, or they have some restrictions for background and camera movement. In this paper, we propose a robust object segmentation method, which can deal with both static foreground object and non-static background. In proposed method, we use depth information to make initial segmented regions and to improve accuracy at following modified active contour model. We also consider using a low resolution camera to set up stereo-pair camera at small cost. Our experiments show that the proposed method extract accurate object shape from low-resolution stereo-pair still images.

In this paper, we propose a simple view synthesis method based on object coding and simple modeling of disparity space. In proposed method, a scene from binocular stereo-vision camera is divided into some objects and planes. Our purpose is not "physically correct" but "subjectively acceptable" view synthesis within video-rate, which will provide convincing images, using MPEG-4 object video coding method. Proposed method uses inter/ extrapolation to generate images from arbitrary viewpoints. It also conceals void area behind objects by using surrounding texture information.

A method of hologram bandwidth reduction and a method of size change of a 3D image are described. Spatial frequency bands of a Fourier-transform hologram (FTH) are superimposed for reduction of the bandwidth and for production of a continuous periodic FTH. Resolution of the image is improved by the superimposing method. The second hologram for reconstruction of the magnified 3D image is produced by connecting a number of small holograms clipped from the original FTH. Image depth capable of magnification is extended using several FTHs. Experiments using the CGH shows that depth of the 3D image can be perceived by watching images reconstructed on many Fourier-transform planes with, different distances from the hologram. It is also shown that numbers of rays of light illuminated from the second hologram reconstruct similar 3D images of various sizes of the same object. Distortion of the image due to the magnification can be avoided over the wide range of magnifying power.

A real-time color holography system is developed using a high-resolution reflective liquid-crystal display (LCD) panel that consists of a 1400×1050 array of square pixels with width of 10.4 micron. Red, green and blue images with high resolution are reconstructed from the holography system with a red laser diode (LD), a green laser and a blue light-emitting diode (LED) as the reference light. The reconstructed color image with high resolution can clearly be observed under the room light. Directly viewable color images with both eyes or images in the wide visual field are reproduced using the 3-channel LCD modulator. The viewing-zone angle or the visual-field angle of the 3-D display system can be expanded up to about 9 degrees using three LCD panels. Fringe patterns for a practical object are also recorded by a high-resolution CMOS sensor, and a moving image of the object is reproduced from the fringe patterns by the developed holographic display system.

A new method of information reduction in hologram is described. Loss of resolution due to the information reduction is improved by superimposing spatial frequency bands of a Fourier transform hologram. Superposition of a number of identical Fourier transform holograms, which deviate each other with a small distance, forms a continuous periodic Fourier transform hologram. The second hologram for the reconstruction of an image is reproduced by repetition of a small area of the continuous periodic Fourier transform hologram. Experiments have been carried out to examine the reconstruction of 3-D images by using computer-generated holograms (CGHs). Results of the experiments show that a high-resolution image is reconstructed from the second hologram produced by superimposing spatial frequency bands. The information reduction effects on the imaging, so that the reconstructed image is spatially sampled with a constant pitch.

A method of changing in size of a three-dimensional (3D) image using a Fourier transform hologram (FTH) or a periodic FTH is described. Here, the periodic FTH is made for information reduction in hologram by superimposing a number of identical FTHs. The second hologram for reconstruction of magnified 3D images is reproduced by connecting a number of small holograms clipped from the original FTH or from the periodic FTH. Numerical calculations and experiments using the computer-generated hologram (CGH) have show that numbers of rays of light illuminated from the second hologram produce a magnified similar 3D image. Distortion of the image owing to the magnification can be avoided by reconstructing the image from a number of small holograms. Resolution, which depends on the magnifying power of the image and on the size of small holograms, is estimated by the numerical calculation.

In video communication applications, there are great demands of high-efficiently coding of video sequences. To improve subjective video quality, preferred ROI (Region of Interest) coding has widely been studied. In this paper, we employ the object coding techniques to encode ROI with higher priority. When we use the object coding to specify ROI, shape of the object does not required high accuracy. Therefore, we can improve the coding efficiency and reduce tracking difficulty by simplification of ROI shape.

記録したモアレ縞から光干渉縞を復元してホログラムを作成すれば, このホログラムを用いて3次元画像を表示することが出来る.本論文では, 単純な処理で短時間にモアレ縞から光干渉縞を復元する方法を提案する.また, 波面再生と結像について数値計算を行い, 作成したホログラムによって表示される画像の解像度を評価する.

わずかに異なる光干渉縞を重ねると波長の長いモアレ模様を生じるが, このモアレ模様を利用して記録すればホログラムの画像情報量を大幅に圧縮できる.3次元画像を光干渉縞の作るモアレ模様として記録できることを示し, モアレ縞を画像データとして読み取る方法を提案する.また, 再生光による結像について数値計算を行い, 表示される画像の解像度を評価する.

A new method is proposed to draw up a hologram using a Moire pattern of interference fringes on the base of the local approximation. Numerical calculation is carried out about reconstruction of the wavefront and formation of 3D images to show validity of a hologram made up from a Moire pattern.

Record of a 3D figure using a Moire pattern of interference fringes is proposed for a purpose of dramatic reduction of data for 3D images. Information of 3D images is recorded as a Moire pattern of interference fringes, and a hologram is made up from this pattern. Numerical results about formation of a 3D image are presented.

This paper proposes a robust hierarchical image transmission system based on the hierarchical quadrature amplitude modulation (QAM) scheme, which gives high-quality image transmission in a band-limited Rayleigh fading channel. Authors examine the selection of Bose-Chaundhuri-Hocquenghem (BCH) error correction codes for two-layer system, and clarified that it is effective to apply forward error correction (FEC) codec to only base significant layer to get higher system performance. By using BCH(63,45,3) code for significant layer, there is about 10dB improvement of the robustness against channel CNR degradation, with slightly image quality degradation in higher channel CNR region. Authors also analyzed the optimum hierarchical parameter in the Rayleigh fading channel which maximizes the received image quality. Using optimized hierarchical modulation, there is another 2 dB improvement of the robustness against channel CNR degradation. © 1998 Elsevier Science B.V. All rights reserved.

This paper proposes a new mobile image transmission system based on the hierarchical modulation scheme for achieving a high quality and high speed digital image transmission in a band-limited fading channel. The proposed system uses a hierarchical QAM (quadrature amplitude modulation) scheme to give unequal transmission reliability depending on the significance of DCT (discrete cosine transform)-based compressed images. Computer simulation results show that the proposed system is an effective high-quality and high-speed image transmission technique in the band-limited fading channel.

This paper proposes a new mobile image transmission system based on the hierarchical modulation scheme for achieving a high quality and high speed digital image transmission in a band-limited fading channel. The proposed system uses a hierarchical QAM (quadrature amplitude modulation) scheme to give unequal transmission reliability depending on the importance of DCT (discrete cosine transform)-based compressed images. Numerical analysis shows that the proposed system is an effective high-quality and high-speed image transmission technique in a fading channel.