Due to the physical structure of single-chip CCD or CMOS color image sensor

there is only a single color component at each pixel position. As a result

color interpolation or color demosaicing is required to reconstruct the other two color components. General linear interpolation method may blur the image edge

and introduce color artifacts near edges. Although state-of-art methods may increase image quality

the computational complexity limits their applications. This paper presents a novel color interpolation method. It effectively increases the quality of interpolated images in three ways. At first

it performs interpolation in color difference space rather then in normal color space. Secondly

it introduces Rational Functions (RF) based operator instead of linear operator. And at last

a post-processing step is employed further to enhance the image quality. Because interpolation in color difference space takes into account the correlations between each color components

and RF based operator is edge-adaptive

this is the reason why the image quality can be improved using this method. In addition

this method is simple and calculating efficient in contrast to some of the state-of-art methods. The experiments compare PSNR and PESNR as while as MSE with the other three methods at the end of this paper.