RT Journal Article
T1 Improved method for isochromatic demodulation by RGB calibration
A1 Quiroga Mellado, Juan Antonio
A1 García Botella, Ángel
A1 Gómez Pedrero, José Antonio
AB The red-blue-green (RGB) calibration technique consists in constructing an a priori calibration table of the isochromatic retardation versus the triplet of RGB values obtained with a RGB CCD camera. In this way a lookup table (LUT) is built in which the entry is the corresponding RGB triplet and the output is the given retardation. This calibration (a radiometric quantity) depends on the geometric and chromatic parameters of the setup. Once the calibration is performed, the isochromatic retardation at a given point of the sample is computed as the one that minimizes the Euclidean distance between the measured RGB triplet and the triplets stored in the LUT. We present an enhanced RGB calibration algorithm for isochromatic fringe pattern demodulation. We have improved the standard demodulation algorithm used in RGB calibration by changing the Euclidean cost function to a regularized one in which the fidelity term corresponds to the Euclidean distance between RGB triplets; the regularizing term forces piecewise continuity for the isochromatic retardation. Additionally we have implemented a selective search in the RGB calibration LUT. We have tested the algorithm with simulated as well as real photoelastic data with good results.
PB The Optical Society of America
SN 0003-6935
YR 2002
FD 2002-06-10
LK https://hdl.handle.net/20.500.14352/58779
UL https://hdl.handle.net/20.500.14352/58779
LA eng
NO © 2002 Optical Society of America.We appreciate the financial support for this work given by the European Union project Advanced Integrated Nondestructive Testing Concepts for Unified Life-Cycle (INDUCE), BRPR-CT98-0805.
NO European Union
DS Docta Complutense
RD 7 abr 2025