A method for determining an alpha value for a candidate pixel of an image in an alpha matting process and an apparatus configured to perform the method are described. A selecting unit selects two or more pairs of foreground pixels and background pixels. A calculating unit calculates for each pair of foreground pixel and background pixel an associated alpha value based on a color of the foreground pixel and a color of the background pixel, as well as a probability function based on the associated alpha value. The probability function is modeled by assuming two or more characteristics of the pixels as statistically independent. A determining unit determines the pair of foreground pixel and background pixel with the highest value of the probability function. A setting unit then sets the alpha value for the candidate pixel to the associated alpha value of the determined pair of foreground pixel and background pixel.