In most linear imaging problems, where the model to be sought is expanded in a set of basis functions, it is common practice to truncate the set al a certain (arbitrary) level. The solution then depends on the chosen parameterization, and neglected basis functions may leak into the solution to produce artifacts in the retrieved model. An unbiased estimate of the coefficients of the true model may be obtained in the chosen finite basis set; here, a method to suppress leakage is illustrated on an example of global seismic tomography.