25 January 2011 Spectral model of an electro-photographic printing system
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At EI 2007 in San Jose, California detailed physical models for monochrome and color electro-photographic printers were presented. These models were based on computer simulations of toner-dot formation for a variety of halftone structures. The optical interactions between the toner-dots and the paper substrate were incorporated by means of an optical scattering function, which allowed for the calculation of optical dot-gain (and physical dot-gain) as function of the halftone structure. The color model used simple red-green-blue channels to measure the effect of the absorption and scattering properties of the cyan, magenta, yellow and black toners on the final half-tone image. The new spectral model uses the full absorption and scattering spectrum of the image toners in calculating the final color image in terms of CIE XYZ values for well-defined color and gray patches. The new spectral model will be used to show the impact of halftone structure and toner-layerorder on conventional dot-on-dot, rotated dot and error diffusion color halftone systems and how to minimize the impact of image toner scattering. The model has been expanded to use the Neugebauer equations to approximate the amount of cyan, magenta, and yellow toners required to give a "good" neutral in the rotated dot halftone and fine tuning is achieved by adjusting the development threshold level for each layer to hold a good neutral over the full tonal range. In addition to the above fine-tuning, cyan, yellow and magenta offsets are used to find an optimum use of the halftone dither patterns. Once a "good" neutral is obtained the impact on dot gain, color reproduction and optimum layer order can studied with an emphasis on how the full spectral model differs from the simpler three-channel model. The model is used to explore the different approaches required in dot-on-dot, rotated dot and error diffusion halftones to achieve good results.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael A. Kriss, Michael A. Kriss, } "Spectral model of an electro-photographic printing system", Proc. SPIE 7866, Color Imaging XVI: Displaying, Processing, Hardcopy, and Applications, 786611 (25 January 2011); doi: 10.1117/12.872224; https://doi.org/10.1117/12.872224


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