• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.331-338
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• 2011

In this paper, we propose a visual fatigue prediction metric which considers individual fusional characteristics for stereoscopic video. It predicts the visual fatigue level by examining the disparity and motion characteristics of 3D videos. In addition, we classified the viewers into 2 groups according to fusional limit and the slope of fusional response which are acquired from random dot stereogram test. Then, Pearson's and Spearman's correlation coefficient was measured between the proposed metrics and the subjective results, acquiring 80% and 79%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.4-5
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• 2011

본 논문에서는 비대칭적 화질을 갖는 스테레오 3DTV 시스템에서 좌우 두 영상의 화질차이가 합성한 스테레오 3D 영상의 주관적 화질을 떨어뜨릴 정도로 현저한 경우, 이 화질 차이를 보상하기 위하여 조건부 대체를 포함한 양안시차 맵을 이용하는 방법을 제안한다. PSNR값 비교를 통하여 화질 개선 정도를 보았고 0.37~18dB 정도의 PSNR 개선을 확인하였다.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.854-865
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• 2014

This paper proposes a method to generate a stereoscopic image pair from a digital hologram by considering the situation that digital hologram data is serviced but the end-user does not have the proper display equipment, etc. We use Fresnel transform as the method to convert a digital hologram into an image. Each image of the stereoscopic image pair uses a part of the given digital hologram and the sizes of the two partial digital holograms for the two images are chosen to be the same. Here, the size of the image is adjusted by the size of the partial digital hologram and the disparity between the pair images is adjusted by the distance between the centers of the two partial hologram. This paper also deals with how to adjust the size and the disparity of the images. In this paper the generated stereoscopic images are implemented as an anaglyphic display type to confirm the feeling of distance by wearing the red-blue glasses.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.34-36
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• 2012

본 논문에서는 비대칭적 화질을 갖는 스테레오스코픽 영상에서 화질개선을 위해 사용되는 부가정보를 효율적으로 부호화하기위한 방안을 제안한다. 부가정보의 대부분은 좌영상과 우영상의 높은 상관도를 기반으로 하는 양안시차 벡터맵으로 구성되며, 이것을 부호화하기 위해 분포 특성을 분석하였고, 이에 맞는 엔트로피 부호화 방식인 지수 골롬 부호를 적용하였다. 또한, 양안시차 벡터맵의 공간적 데이터의 중복성을 없애기 위해 DPCM을 적용하여 부호화의 효율성을 높였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.6-7
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• 2011

본 논문에서는 비대칭적 화질을 갖는 양안식 3DTV 시스템에서 좌우영상간의 화질차이가 크게 발생하는 경우, 열화된 우영상의 화질을 보상하기위한 부가정보로 양안시차 벡터맵을 사용하는데, 이때 넓은 대역폭을 갖는 부가정보를 효율적으로 부호화하여 전송하기위한 방법을 제안한다. 공간적인 중복성을 피하기 위해 쿼드트리 분해방식을 적용하였고, 양안시차 벡터의 시간적 중복성을 고려하여 부호화 효율을 높였다. 제안된 압축 알고리듬인 가변블록 부호화 방안을 적용한 복원영상은 비슷한 전송률을 갖는 고정블록 복원영상에 비해 개선된 PSNR을 가짐을 실험을 통해 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.365-367
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• 2012

하이브리드 양안식 비디오 부호화 방식은 한정된 대역폭 내에서 MPEG-2 기반의 기존 2D 디지털 방송서비스를 지원하면서, 동시에 추가적인 시점 영상을 MPEG-2 가 아닌 비디오 부호화 표준을 사용함으로써 3DTV 방송 서비스를 가능하게 한다. 본 논문에서는 기존의 2D 디지털 방송 서비스를 위한 좌안 영상은 MPEG-2 로 부호화되어 지상파로 전송되고, 3DTV 방송에 필요한 우안 영상은 HEVC 로 부호화되어 인터넷으로 전송되는 방송 상황을 가정한다. 또한 MPEG-2 로의 좌안 영상 부호화 시의 파생 정보를 활용하여 HEVC 로의 우안 영상 부호화 시의 성능 향상을 도모한다. 이를 위해 우선 기존 HEVC 를 움직임 벡터에 기반한 예측 부호화뿐 아니라 변이 벡터에 기반한 시차간 예측 부호화가 가능한 구조로 확장한 후, 움직임 벡터 부호화를 위해 HEVC 에 포함된 AMVP 기술을 변이 벡터가 사용됨에 따라 발생할 수 있는 여러 상황을 고려하여 확장한다. 실험결과 제안하는 하이브리드 양안식 부호화기로 우안 영상을 부호화할 경우에, 단독으로 HEVC 를 사용하여 우안 영상을 부호화하는 경우와 비교하여 BDBR 측면에서 평균 34.49%의 성능 향상을 관찰할 수 있었다.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.66-76
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• 2013

Although there has been much advance in the development of 3D displays of various purpose, 3D contents are not yet so used as expected in those displays. One well-known obstacle in the enjoyment of 3D contents is visual fatigue, but another major issue is image distortion of 3D contents. In the previous research, Shin, Li, & Kim (2012) reported systematic linear relationship between screen disparity and size perception of a simple object whose retinal size was constant across different disparities. In this research, we intended to generalize the previous finding by using various 3D stimuli in the test of the relationship between screen disparity and size perception of those stimuli. Consistent with previous findings, our data indicated that size perception linearly changes as a function of screen disparity and the linearity was observed in all stimuli types we used in this research. We described the empirical relationship between screen disparity and size perception in the form of prediction function for size perception in which visual angle is the predictor. This function will be very useful in the creation of 3D contents as one can make reasonable predictions on the to-be-perceived size of an object being filmed using screen disparity of their camera setting.

• Journal of Broadcast Engineering
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• v.20 no.6
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• pp.901-911
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• 2015

Many studies tried to develop a 3D display based stereo test as a substitute for the conventional stereo test. Although many 3D monitor based stereo tests have various advantages over the conventional stereo tests with printed stimuli, they have a crucial limitation in manipulating disparity. The least value for disparity manipulation is one pixel, which is too big to screen the normal stereo acuity in pc environment with a short viewing distance. In this explorative study, a Gabor image was employed as a test stimulus, because its position can be manipulated by changing its phase information, which allows sub-pixel manipulation for disparity. Instead of employing the methods of the conventional stereo tests where measurement was made only once for each of a wide range of disparity values, 10 replications were administrated for each of 6 disparity levels. The results from the test using Gabor images were compared with those using random dot stimulus because the latter stimulus was exactly the same as that of the conventional stereo test. The correlation coefficient between two tests was found to be moderate. After one month later, the whole test was repeated in the same settings. The correlation coefficient between test and retest results from Gabor images was found to be as high as that from a random dot stimulus, implying high test-retest reliability. These results suggest that a Gabor stimulus could be used as a test stimulus for the valid and reliable stereo test, even in the limited condition, such as 3D environment with a short viewing distance and a condition for evaluating the stereo acuity very precisely.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.225-236
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• 2013

3D contents could cause unique 3D visual fatigue. Screen disparity, image blurring, and crosstalk are known to be the three major factors responsible for the fatigue. Among these, screen disparity and image blurring are content factors, that is, one can directly manipulate contents themselves to handle visual fatigue caused by these two factors. On the other hand, because crosstalk is closely tied to physical characteristics of 3D display, it is difficult or even impossible to reduce crosstalk-driven visual fatigue unless one replaces 3D display itself (for example, from active to passive display). However, the effects of crosstalk on 3D visual fatigue depends on visual stimulus features (that is, contents), and thus it is possible to manipulate stimulus features in order to handle visual fatigue caused by crosstalk. Hence, this research tested the effects of visual stimulus features on crosstalk (which then causes 3D visual fatigue). Using relative depth discrimination task, we tested the effects of stimulus-background contrast, background texture density, and screen disparity on the degree of perceived crosstalk. The results showed that crosstalk decreases with presence of background texture and with less degree of screen disparity.

• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.76-86
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• 2016

This study was investigated whether the perceived depth was changed depending on the measurement methods. In the method of direct comparison, virtual object with one of the various binocular disparities was presented in the frontal space with LEDs which were used for depth estimation for a binocular stimulus, while in the method of indirect comparison, visual object was presented in the frontal space but the LEDs were placed rightward at the angle of 45 degree from the mid-sagittal line. In these experimental setup, the depth of binocular stimulus was directly matched that of LED in direct comparison condition. In indirect comparison condition, however, observer estimated the depth of binocular stimulus, turned one's head rightward to the array of LEDs and turned on the LED which was supposed to be the same depth as binocular stimulus. Additionally, it was investigated whether the perceived depth was different depending on observer's stereo acuity. The results showed that perceived depths measured in the direct comparison were more similar to the depth predicted from geometry than those in the indirect comparison, and that the perceived depths from observers with high stereo acuity were similar to the predicted depth from geometry those from observers with low stereo acuity. These results indicated that stereoscopic depths of the binocular stimuli would vivid and compelling when binocular stimuli was simultaneously presented with real objects in the same visual space, like a mixed reality.