Estimation of Backing Influence on Halftone Reflectance

Matthias Scheller Lichtenauer1, Hanno Hoffstadt2, Andreas Kraushaar3, Berthold Oberhollenzer3, Peter Zolliker1 1EMPA, Switzerland, 2GMG GmbH & Co. KG, 3Fogra, Germany Download paper Play (18min) Download: FLV | MOV | OGG | MP3

In the graphic arts industry, there is a need to convert colorimetric readings taken on one backing (usually white) to values that would have been measured with a different backing (usually black). We describe and compare different models for such a conversion. Starting from published models using linear scaling, we developed a new nonlinear model for a strongly scattering substrate. Another new model was derived from the Clapper-Yule model, which includes effects of internal reflectances. All these models are applicable in both the spectral and the tristimulus domain.

For calibration, we used measurements of the bare substrate on both backings. We intentionally make only use of the measured spectral or XYZ values, and do not require knowledge of the nominal CMYK values. This is particularly useful for arbitrary patches measured with a stand-alone measurement device. The test data sets consisted of a large set of test prints, originating from digital or conventional printing processes, and covering typical ranges of mass per area. Both new models outperformed linear regression models and the spectral versions always yielded better results than their corresponding versions in tristimulus space.

You may also like:

1. Chromatic Effects of Metamers of Daylights
2. Spectral Image Prediction of Color Halftone Prints Based on Neugebauer Modified Spectral Reflection Image Model
3. Comparison of Colour Difference Methods for Natural Images
4. Noise Analysis of a Multispectral Image Acquisition System
5. Surface Reflectance Models Based on Characteristic Functions