MTF Measurement for inkjet printing on silk fabrics

Abstract

The modulation transfer function (MTF) is a standard method used for estimating the image quality of a component for detail recording in an imaging forming system such as lens, scanner etc., and printing quality of the final products (film, paper and fabric). The texture of the silk fabric affects the inkjet ink printed quality since the light scattering phenomena in silk fabric produces optical dot gain, which has a large influence on the sharpness of printed quality. This study focused on the measurement of MTF of the non-printed silk fabrics and correlation of the MTF data to sharpness of the printed silk fabric with the in-house formulated inkjet ink. The MTF of silk fabric surface was measured using the sinusoidal test pattern contacted on silk fabrics with the test target frequency ranged from 0.375 to 3.0 lp/mm. The sinusoidal test target was then scanned by a microdensitometer, which recorded the reflection density. This data comprised two frequencies. The high frequency is the characteristic of a silk fabric while the low frequency is the light scattering of silk yarns in contact with sinusoidal targets. The sinusoidal curves at the low frequency were used for further calculation of the MTF values. The result indicated that the measurement of MTF of silk fabric using the contact sinusoidal method can be used to find the point spread function of silk fabrics (PSF). This research investigated the relationships of weave direction, wicking properties, and the MTF of four different silk fabrics. Silk fabrics A, C, and D are plain weave but silk B is twill weave. The dot gain effect by Yule-Nielsen model was investigated to confirm the MTF technique. The coefficient d calculated by the MTF empirical model is 0.0604 for the silk D, and the coefficient n by Yule-Nielsen model is 1.636 for silk D, too. The silk D has the least d and n coefficients compared with all silk fabrics, i.e. it gives good quality on sharpness as well.