Exploring ink spreading

This study aims at exploring ink spreading, which causes significant colour deviations in ink-jet printing. We present a method for investigating this phenomenon by considering only a limited number of cases. Using a combinatorial approach based on Polya's counting theory, we determine a small set of ink drop configurations which allows to deduce the ink spreading in all other cases. This improves the estimation of the area covered by each ink combination which is crucial in colour prediction models. Such models simplify the calibration of ink-jet printers

Prediction of the Reflection Spectra of Three Ink Colour Prints

We have developed a colour prediction model and an ink-spreading model. The present study aims at confirming the validity of both models for the case of ink-jet prints using cyan, magenta and yellow inks. Our colour prediction model, augmented by the ink-jet spreading model, predicts accurately the reflection spectra of halftoned samples printed on an HP printer and on an Epson printer. For each printer, the reflection spectra of 125 samples uniformly distributed in the CMY colour cube were computed. The average prediction error between measured and predicted spectra is about ΔE = 2.5 in CIELAB. The model requires the estimation of a set of parameters which are deduced from a small set of measured samples. Such a model simplifies the calibration of ink-jet printers, as well as their recalibrations when ink or paper is changed

Optimisation of surface coverage paths used by a non-contact robot painting system

This thesis proposes an efficient path planning technique for a non-contact optical “painting” system that produces surface images by moving a robot mounted laser across objects covered in photographic emulsion. In comparison to traditional 3D planning approaches (e.g. laminar slicing) the proposed algorithm dramatically reduces the overall path length by optimizing (i.e. minimizing) the amounts of movement between robot configurations required to position and orientate the laser. To do this the pixels of the image (i.e. points on the surface of the object) are sequenced using configuration space rather than Cartesian space. This technique extracts data from a CAD model and then calculates the configuration that the five degrees of freedom system needs to assume to expose individual pixels on the surface. The system then uses a closest point analysis on all the major joints to sequence the points and create an efficient path plan for the component. The implementation and testing of the algorithm demonstrates that sequencing points using a configuration based method tends to produce significantly shorter paths than other approaches to the sequencing problem. The path planner was tested with components ranging from simple to complex and the paths generated demonstrated both the versatility and feasibility of the approach