Abstract: This paper introduces the transfer function based on extended sample （ESTF ） to adjust transfer function parameters. ESTF generalizes the original resample-based transfer functions to the resample-segment-based ones by the extended sample model. The resample-segments instead of the resamples are used as the composition units. The optical attributes of the resample-segments are precomputed on the basis of resample-based transfer function.Meanwhile,filters are introduced to the process of computing ESTF.The experimental results show that ESTF produces better rendering results than the original transfer function for both low-sampling rendering and over-sampling rendering,and is especially suitable in the case of low sampling rendering.Additionally,various rendering effects can be achieved by combining ESTF with different filters.