Irène Foucherot

An inverse display color characterization model based on an optimized geometrical structure

We have defined an inverse model for colorimetric characterization of additive displays. It is based on an optimized three-dimensional tetrahedral structure. In order to minimize the number of measurements, the structure is defined using a forward characterization model. Defining a regular grid in the device-dependent destination color space leads to heterogeneous interpolation errors in the device-independent source color space. The parameters of the function used to define the grid are optimized using a globalized Nelder-Mead simplex downhill algorithm. Several cost functions are tested on several devices. We have performed experiments with a forward model which assumes variation in chromaticities (PLVC), based on one-dimensional interpolations for each primary ramp along X, Y and Z (3×3×1-D). Results on 4 devices (2 LCD and a DLP projection devices, one LCD monitor) are shown and discussed.

New methods for analysing colour texture based on the Karhunen-Loeve transform and quantification

In this article, we offer an original study on the analysis of the texture of colour images based on Local Linear Transforms (LLT). Our colour approach is based on the separability of the data which reduces the number of texture parameters. We also propose the extension of Run Lengths (RL) and Co-occurrence Matrixes (CM) to colour images. In this respect, two different ways were explored (data merging and quantification). We finally present a comparative study showing the efficiency of the first method (LLT) as well as the complementary nature of the other methods (RL, CM).

Reduction of the number of spectral bands in Landsat images : a comparison of linear and nonlinear methods

We describe some applications of linear and nonlinear pro- jection methods in order to reduce the number of spectral bands in Land- sat multispectral images. The nonlinear method is curvilinear component analysis CCA, and we propose an adapted optimization of it for image processing, based on the use of principal-component analysis PCA, a linear method. The principle of CCA consists in reproducing the topol- ogy of the original space projection points in a reduced subspace, keep- ing the maximum of information. Our conclusions are: CCA is an im- provement for dimension reduction of multispectral images; CCA is really a nonlinear extension of PCA; CCA optimization through PCA called CCAinitPCA allows a reduction of the computation burden but provides a result identical to that of CCA.

A geometrical approach for inverting display color-characterization models

— Some display color-characterization models are not easily inverted. This work proposes ways to build geometrical inverse models given any forward color-characterization model. The main contribution is to propose and analyze several methods to optimize the 3-D geometrical structure of an inverse color-characterization model directly based on the forward model. Both the amount of data and their distribution in color space is especially focused on. Several optimization criteria, related either to an evaluation data set or to the geometrical structure itself, are considered. A practical case with several display devices, combining the different methods proposed in the article, are considered and analyzed.

Intelligent knowledge manipulation in PROLOG

Dynamic processing of knowledge in PROLOG is currently done using assert/retract predicates. The consequence of the use of such predicates is that the declarativity of the language is once again put in the wrong. In this paper, we present a new approach for assert/retract in PROLOG, based on an extension of the algorithms used for incremental generation of syntactic parsers.<<ETX>>

A new logical view of knowledge manipulation with PROLOG

Dynamic knowledge processing in PROLOG is currently done using assert/retract predicates. The first consequence of such a facility is that these predicates cause problems for the declarativeness of the PROLOG language. Moreover, a second consequence is that the consistency of the PROLOG programs that use such predicates is no longer guaranteed. To solve this latter problem, the authors introduce a new vision of assert/retract predicates in the PLEASE system.