The improvement of Yule-Nielsen modified spectral Neugebauer model incorporating a single halftone reproduction curve of various ink by dot surfaces coverages depending on the ink superposition conditions was analyzed. In the first model, the ink spreading which occurs when an ink halftone is printed on top of one or two solid inks was considered. In the second model, the concept was generalized to ink halftones printed on top or below solid inks. Results show that for thermal transfer prints at 75 lpi, ink spreading in all superposition condition reduces the mean prediction error.