We propose a new method which compensates optical axes misalignment along with stereo camera zooming automatically. Optical axes misalignment is modeled as image sensor center translation from the lens center. To match the image points of left and right image, right camera translation and rotation equation is devised. By using these equations we can easily get the rig calibration value. Then, we can compensate optical axes misalignment by saving and applying this rig calibration information when we change the zoom of stereo camera. The explanation of the proposed method and devised equation will be provided. And experimental verification results using stereo camera rig will be presented in the paper.
We developed a new multi-view camera system composed of 9 cameras for capturing multi-view images and utilizing
them in research and exhibition. The system is composed of cameras, rig, convergence controller, LANC signal
controller, IEEE 1394 signal interface. And, we made a control program that can manage a record function and other
various camera parameters at PC. By this program, we can shoot multi-view scenes manipulating each element camera
independently or all 9 cameras totally. After the capturing, we transform the image into the glass-less multi-view display
format, and then we can enjoy natural multi-view images at lenticular display.
KEYWORDS: Computer programming, Scalable video coding, Video, Lithium, Quantization, Signal detection, Video coding, Electroluminescence, Communication engineering, Telecommunications
We introduce an efficient mode selection method in the enhancement layers of spatial scalability in the SVC encoder by selectively performing the inter-layer residual coding of the SVC. The proposed method is to make an analysis of the characteristics of integer transform coefficients for the subtracted signals for two residuals from lower and upper spatial layers. Then it selectively performs the inter-layer residual prediction coding in the spatial scalability if the SAD values of inter-layer residuals exceed adaptive threshold values. Therefore, by classifying the residuals according to
the properties of integer-transform coefficients only with the SAD of inter-layer residual signals between two layers, the SVC encoder can perform the inter-layer residual coding selectively, thus significantly reducing the total encoding time with 51.2% in average while maintaining the RD performance with negligible amounts of quality degradation.
In this paper, a fast intermode decision scheme which is suitable for the hierarchical B-picture structure in which much computational power is spent for combined variable block sizes and bi-predictive motion estimation is introduced. The hypothesis testing considering the characteristics of the hierarchical B-picture structure in the proposed method is performed on 16x16 and 8x8 blocks to have early termination for RD computation of all possible modes. The early termination in intermode decision is performed by comparing the pixel values of current blocks and corresponding motion-compensated blocks. When the hypothesis tests are performed, the confidence intervals to accept the null hypothesis or not are decided according to the temporal scalability levels under the consideration of properties of hierarchical B-pictures. The proposed scheme exhibits effective early termination behavior in intermode decision of temporal scalabilities and leads to a significant reduction up to 69% in computational complexity with slight increment in bit amounts. The degradation of visual quality turns out to be negligible in terms of PSNR values.
We have devised a new and efficient method of zoom-convergence interlocked control in the moving-parallel axes style stereoscopic camera system. We set up a simple and smart algorithm of our own, which is based on the basic geometry of the stereoscopic camera system. And, instead of making the Look-Up-Table by measuring the zoom value and the convergence at each step, we utilized the lens data sheet, which can be obtained from the lens manufacturer, so that we can secure the accuracy and the handiness without any measuring.
The geometric differences between left and right images are known as a main factor of eye fatigue in the stereoscopic system. We developed a real-time stereoscopic error corrector which can adjust the vertical errors, the disparity, and the size (field of view) errors of HD moving pictures in VCR tape. The main idea of this system is to extract and use only the common area of both images by cropping the left and right images independently. For this system, we developed a realtime HD scaling hardware and stereoscopic error correcting software. We tested the system with the video streams taken by our HD stereoscopic camera. As a result, we confirmed that the developed system could reduce the efforts and time for correcting the stereoscopic errors compared to the other methods. We also developed a real-time zoom-convergence interlocked controller for HD parallel-axis stereoscopic camera using the same hardware. Because it doesn't need motors for parallax move, we could control the convergence more smoothly while locking it with zoom.
We have improved the HD stereoscopic camera system reported last year. Though the previous version shows good performance in many aspects, we felt some more accurate control mechanism should be realized after various types of trial shooting in field. So we have changed several parts of it. For controlling the separation between two cameras and the convergence of the parallel-axis style stereoscopic camera system, we replaced the linear motor system in the first version with small DC motors. And by changing the lens with full-digitally controlled HD lens, we could control both of the lenses more accurately. For the preparation of the real-time image composition with computer graphics, namely mixed-reality, in this version we fixed the updating frequency of the camera parameters to 60 Hz. In addition, for better zoom-convergence interlocked control, we made the look-up table with much more steps so even smoother operation of zoom-convergence control is accomplished. And, we have done subjective evaluation test on the acquired pictures. As we have implemented the function of storing and retrieving the major parameters of the stereoscopic camera, we could precisely analyze the relationship between the result of picture quality assessment and the camera parameters.
This paper presents an efficient joint disparity-motion estimation algorithm and fast estimation scheme for stereo sequence CODEC. In stereo sequences, frames from one camera view (usually the left) are defined as the base layer, and frames from the other one as the enhancement layer. The enhancement-from-base-layer prediction then turns out as a disparity-compensated prediction instead of a motion-compensated prediction. Although the disparity-compensated prediction fails, it is still possible to achieve compression by motion-compensated prediction with the same channel. At the same time, the base layer represents a monoscopic sequence. Joint disparity-motion estimation can increase coding efficiency and reduce complexity of stereo CODEC using relationship between disparity and motion fields. The disparity vectors are estimated by using the left and right motion vectors and the previous disparity vectors in each time frame. In order to obtain more accurate disparity vectors, we include spatial prediction process after joint estimation. From joint estimation and spatial prediction, we can obtain accurate disparity vectors and then increase coding efficiency. Moreover, we proposed fast motion estimation technique which utilizes correlation for motion vectors of neighboring blocks. We confirmed PSNR of the proposed method increases by 0.5~1.5dB compared to the conventional methods from simulation results. At the same time, the processing time is reduced by almost 1/10.
We have developed a reliable and practical HD stereoscopic camera system. It consists of a pair of full digital box-type HD video camera, small radius SD class lens, a multiplexer board and some other control boards. The camera is a parallel-axes style. We control the convergence by moving the lens slightly inward which is separated from the camera body. We have used two sets of linear motor modules to control the convergence and the distance between the two cameras precisely. The various camera parameters concerned with stereoscopic view can be displayed in the viewfinder, stored with video and used for studying picture quality improvement and assessment. We have combined zoom control with convergence control for the convenience of stereoscopic image capturing, so we can control them with one knob. They also can be controlled individually. The built-in multiplexer board receives two video signals from the left and right camera, and makes them into one side-by-side image that is compressed in half horizontally and multiplexed two images. After this process we can record the video into a normal VCR, then reconstruct the original two images by demultiplexer, and we can enjoy stereoscopic images.
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