Interpolation method for enlarging an image

An interpolation method used by a microprocessor for enlarging an image by inserting pixels into the image, wherein the image is composed of plural scanning lines, the method comprising the steps of:

• (A) selecting four continuously adjacent pixels xk−1, xk, xk+1, and xk+2 which have the pixel values f(xk−1), f(xk), f(xk+1), and f(xk+2) respectively on each scanning line;
• (B) determining three linear equations Lk−1, Lk, and Lk+1 according to every two continuously adjacent pixel values f(xk−1) and f(xk), f(xk) and f(xk+1), and f(xk+1) and f(xk+2);
• (C) selecting a pixel x to be interpolated between the pixel xk and the pixel xk+1;
• and
• (D) applying the pixel x to the three linear equations Lk−1, Lk, and Lk+1 to determine three candidate pixel values, respectively, which are weighted and combined to obtain a pixel value f(x) of the pixel x,
• wherein the pixel value f(x) of the pixel x is f(x)=w1×[slope1×(1−s)+f(xk−1)]+w2×[slope2×(1−s)+f(xk)]+w3×[f(xk+1)−slope3×s], where slope1, slope2, and slope3 are slopes of the linear equations Lk−1, Lk, and Lk+1, respectively, s is a ratio of a distance from the pixel xk to the pixel x to a distance from the pixel xk to the pixel xk+1, 1−s is a ratio of a distance from the pixel x to the pixel xk+1 to a distance from the pixel xk, to the pixel xk+1, and w1, w2, and w3 are the weighting values.