Journal of Broadcast Engineering (방송공학회논문지)

The Korean Institute of Broadcast and Media Engineers (한국방송∙미디어공학회)
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Modified cubic convolution scaler for edge-directed nonuniform data

Edge 방향의 비균등 데이터를 위한 개선된 Cubic Convolution Scaler

  • 김상미 (세종대학교 정보통신공학과) ;
  • 한종기 (세종대학교 정보통신공학과)
  • Published : 2008.09.30
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Abstract

We derive a modified version of the cubic convolution scaler to enlarge or reduce the size of digital image with arbitrary ratio. To enhance the edge information of the scaled image and to obtain a high-quality scaled image, the proposed scaler is applied along the direction of an edge. Since interpolation along the direction of an edge has to process nonuniformly sampled data, the kernel of the cubic convolution scaler is modified to interpolate the data. The proposed scaling scheme can be used to resize pictures in various formats in a transcoding system that transforms a bit stream compressed at one bit rate into one compressed at another bit rate. In many applications, such as transcoders, the resolution conversion is very important for changing the image size while maintaining high quality of the scaled image. We show experimental results that demonstrate the effectiveness of the proposed interpolation method. The proposed scheme provides clearer edges, without artifacts, in the resized image than do conventional schemes. The algorithm exhibits significant improvement in the minimization of information loss when compared with the conventional interpolation algorithms.

본 논문에서는 디지털 영상의 해상도를 임의의 배율로 확대 또는 축소하기 위해 사용되는 개선된 cubic convolution scaler를 제안한다. 화면 해상도 변경 시 엣지 부분에서 큰 왜곡이 발생되는 문제를 극복하기 위하여 제안하는 해상도 변환 방법은 영상의 edge의 방향에 따라 적용되며, 이것은 해상도 변환된 영상의 edge 특징을 잘 보존시킬 뿐 아니라 영상의 화질도 좋게 한다. 하지만 영상 보간에 사용되는 edge 방향 데이터들이 비균등 간격으로 위치하는 특징을 가지므로 cubic convolution의 kernel을 이에 맞게 새롭게 설계하였다. 제안하는 해상도 변환 방법은 transcoder와 같이 해상도 조정을 필요로 하면서 변환된 영상의 화질을 우수하게 유지하여야 하는 여러 응용분야에서 중요하게 사용된다. 실험 결과에서는 제안하는 방법으로 변환된 영상이 기존 보간 방법을 사용하여 변환된 영상에 비해 artifact를 가지지 않으면서도 좀 더 깨끗한 edge 정보를 가지고 있다는 것을 보여준다. 또 기존 방법에 비해 제안하는 방법은 해상도 변환에 의한 정보의 손실을 최소화 하였다.

Keywords

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