The dependence of color on the surface state of an object is calculated in the context of spectrophotometric measurements in a back-scattering configuration. A modification of the surface roughness leads to a vertical shift of the reflectance spectrum. This translation is related, on a physical basis, to the relevant characteristic of the topography: the ratio h/l (ie, r.m.s. roughness/surface correlation length). Changes in L*a*b* colorimetric coordinates associated with this translation are computed. Finally, the color change DeltaE is related to the surface state modification via the ratio h/l. Computations show that the color becomes lighter and less saturated when the surface becomes rougher. The color change is more important for dark or saturated initial objects, and also more important for a yellow surface than for a blue one. Finally, the minimum roughness modification that can induce a visible color change is determined. These results could be applied for industrial needs (quality control), or in the artistic field of conservation or restoration (to follow the color of paintings).