Image filter is one of the primary influencing factors for image processing and reproduction in spatial gamut mapping. The primary target of filter is to decompose the image into several bands and then to use different gamut mapping methods to get high quality reproduction in the spatial gamut mapping framework. Gaussian filter, mean filter and bilateral filter etc. are often used in spatial gamut mapping. For the same filter, the scale parameter plays a critical role in improving the image processing and reproduction quality. In this paper, Gaussian filter and bilateral filter were used to process the digital original images based on the theory of printing image processing in spatial gamut mapping. Various filter scale parameters were selected to decompose the originals into low band images and high band images in color gamut mapping and to study on the relations between the scale parameter and filtered image. The results indicated that the appropriate filter parameters contribute to influence the properties of different band images then to influence the gamut mapping quality. And it helps to improve the spatial gamut mapping algorithms and improve the gamut mapping quality.