Analysis Of Print Quality Based On MTF

Image quality of print is highly dependent on the paper characteristic such as dot gain which is including two kinds: mechanical dot gain and optical dot gain. The main reason for optical dot gain is light scattering in the printing paper. The modulation transfer function (MTF) is usually applied to represent the light-scattering phenomenon for the analysis of the imaging characteristics of print and paper. In order to make a theoretic foundation for the next work, this paper is beginning with a brief summarize about MTF; To study the optical characteristics of printing paper, this paper introduce a MTF-based spatial-spectral halftone predication model, then establish the relationship between the reflected fractionρ, transmitted fractionτ, paper scattering coefficient d and general spectral reflectance R(x,y), transmittance T(x,y). Then, calibrate the coefficients based on the situation of solid patches of primary inks(CMYK), as well as considering only single side prints. Finally, we get eleven parameters to estimate. We obtain the spectral reflectance and transmittance curve of every solid patches for the primary colors. Then estimate the parameters which minimize the deviation between the measured spectra and their calculated predications by using MATLAB. Thus, we can calculate the paper R(x,y) by the prediction function if give a set of parameter values for a particular paper-ink combination. Then, we can predict the optical dot gain for idealized halftone prints based on the Murry-Davies model, which has important instruction for the calibration of the color printers as well as the controlling and evaluation of the prints. At last, designing experiment to validate the model, and apply this experiment to different kinds of papers in order to analyze the optical scattering performance of them.