Quick matting: A matting method based on pixel spread and propagation

The problem of matting is always solved by finding the alpha value for each pixel in the image. Many recent methods combine color sampling and affinity definition in different steps, leading to large computational cost. In the proposed method, when the alpha value of a pixel Pi is calculated, the pixel is regarded as a foreground pixel to help calculate its adjacent pixels' alpha values, resulted in a faster solution. This spreading way of traversal also ensures local continuity of foreground object and improves the visual result. Experiments show our Quick Matting can achieve comparable alpha mattes as Robust Matting, while the speed is enhanced by about 25 times.