Color correction of images for a non-linear device uses its characterization function, often evaluated by rectilinear interpolation of a table of measurements. Sequential linear interpolation (SLI) instead allows more freely distributed grid points, but usually requires remeasure-ment to place them optimally. We smooth the measured data with a tensor-product spline before using a fast SLI look-up table: noise is reduced, and the spline curvature reveals choice SLI grid locations without remeasurement.