구간별 선형 변환방법을 이용한 스캐너RGB로부터 기기 독립적인 칼라로의 변환

초록

Flatbed color image scanner is one of the most popular color image input devices. The colors of the digitized image on display often appear different from the corresponding colors on the hardcopy. This color distortions are mainly due to the nonlinear spectral sensitivities of the sensors and differences in color gamuts. Most important step for the color matching is the color coordinate transformation from the scanner RGB space to device independent uniform color space. The linear transformation and look-up table (LUT) based approaches are typical color coordinate transformation techniques for the low to mid range and high-end scanners, respectively. The former is computationally inexpensive but results in larger ΔＥ than the latter．As an alternative, a piecewise linear transformation is proposed in this paper for the color coordinate transformation. The RGB color space is divided into non-overlapping cubes until size of subcube is equal or larger than a predetermined minimum size or modelling error is smaller than a threshold value. Experiments are performed to evaluate the proposed technique. Experimantal results are compared with those obtained by the conventional linear transformation and LUT based methods. Also, computational complexity of the proposed technique is compared with the LUT based method.