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The calibration of color printers is highly influenced by optical scattering. Light scattered at microscopic level within printed papers induces a blurring phenomenon that affects the linearity of the tone reproduction curve. The induced nonlinearity is known as optical dotgain. Engeldrum and Pridham analyzed its impact on printing, using Oittinen's light scattering model. They determined the scattering and absorption coefficients based on spectral measurements of solid patches only. Their calibration achieves good independence of any printing irregularities. However, the microscopic knife-edge measurements of Arney et al. showed that the model overestimates the influence of the absorption coefficient. Unlike Oittinen's model, we directly approach the laterally scattered light fluxes. This is achieved by an extended three-dimensional Kubelka-Munk model. We describe how to determine our coefficients using measurements of mere solid patches, which allows us to decouple the optical dot gain from other printing influences. Our improved model successfully corrects the observed overestimation and is able to predict Arney's microscopic measurements.

The modulation transfer function (MTF) is a standard method used for estimating the image quality of a component for detail recording in an image forming system and for printing quality of the final products. This study focused on the measurement of MTF of nonprinted and printed silk fabrics and a correlation of the MTF data to sharpness of the printed silk fabric using the in-house formulated ink jet ink. The MTF of the surface was measured using the sinusoidal test pattern in contact with the fabric using spatial frequencies from 0.375 to 3.0 cycles/mm. The sinusoidal test target scanned by a microdensitometer in the reflection density mode. These data comprise two frequencies; the high frequency is the characteristic of the fabric while the low frequency is the light scattering of the yarns in contact with the sinusoidal target. 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 find the point spread function of silk fabrics. This research investigated the relationships of weave style and direction, wicking properties, and the MTF of four different silk fabrics with plain weave (silk A, C, and D) or twill weave (silk B). Dot gain by -the Yule-Nielsen model was investigated. The coefficient d calculated by the MTF empirical model was 0.0604 and the coefficient n by the Yule-Nielsen model was 1.636 for silk D which had the lowest d and n coefficients compared with other silk fabrics, indicating good quality in terms of image sharpness.

Methods for understanding the fundamental mechanisms of laser photothermal imaging are described and applied to model imaging media. The light response is characterized with a series of Gaussian laser pulses of varying intensities and durations. The results are compared to a reference model, the "local fluence" model, that assumes the likelihood of exposure at a given pulse duration depends solely on the laser fluence received at that location. The mechanisms underlying the material behavior are studied with time-resolved microscopy using a variety of exposure and viewing conditions. The imaging media have in common a silicone rubber (polydimethylsiloxane) coating that can be removed by a single laser pulse to form an imaged spot that attracts ink. They differ in having a thin-film absorber layer, a volume absorber layer, or a combination of volume absorber and energetic underlayer. The thin-film media are the least sensitive with longer duration microsecond pulses but the most sensitive with nanosecond pulses, which is explained using a thermal conduction model. The volume absorbing media show deviations from the local fluence model that indicate the existence of useful dot gain properties which improve sensitivity. Time-resolved microscopy shows that this dot gain results from high-speed mechanical effects caused by hot gas trapped under a silicone rubber balloon.

The color of a print is affected by ink spreading and lateral light scattering in the substrate, making printed dots appear larger. Characterization of physical and optical dot gain is crucial for the graphic arts and paper industries. We propose a novel approach to separate physical from optical dot gain by use of a high-resolution camera. This approach is based on the histogram of microscale images captured by the camera. Having determined the actual physical dot shape, we estimate the modulation transfer function (MTF) of the paper substrate. The proposed method is validated by comparing the estimated MTF of 11 offset printed coated papers to the MTF obtained from the unprinted papers using measured and Monte Carlo simulated edge responses.

Most of the color prediction models use a single dot gain curve for each primary ink. In the proposed model, the behaviour of the dot gain of each primary ink is characterized by three curves based on CIEXYZ tri-stimulus values. In our previous works, it was shown that the usage of three characterization curves for each primary ink reduced the color difference between the predicted and measured data compared with the simple Yule-Nielsen model. In the present paper, an effective coverage map based on CIEXYZ is created. This map presents the effective coverage values of the primary inks corresponding to different ink combinations. Given any reference ink combination, the effective coverage values of the involved primary inks are estimated by cubic interpolation. Compared to our previous models, the proposed model gives significant reduction in the color difference between the predicted and the measured data.

Characterization of total dot gain gives a good insight to the study of paper and print. In this article, we propose three approaches based on the Murray-Davies model to obtain total dot gain. In t ...