Use of Multispectral Microscopy in the Prediction of Coated Halftone Reflectance.

When a print is coated with a transparent layer, such as a lamination film or a varnish layer, its color can be modified compared to the uncoated version due to multiple reflections between the layer-air interface and the inked substrate. These interreflections involve a multiple-convolution process between the halftone pattern and a ring-shaped luminous halo. They are described by an optical model which we have developed.

High dynamic range capture and sensor calibration to improve microscale halftone ink and paper surface quantification.

Microscale measurements of halftone dots allow us to investigate the ink transmittance as a function of the position on the halftone dots and to characterize the edges of the halftone dots. In this work, an optical microscope mounted with a commercial camera and a High Dynamic Range (HDR) capture method were combined to measure accurately the printed dots at the microscale. Each stage of the method development has been quantified and compared to simple imaging.