  We carried out an experimental set-up for reading a hidden drawing under
papyrus using an optical technique based on the speckle phenomenon that is
observed when a rough surface is illuminated by laser light. We propose the use
of several wavelengths of light illumination and adaptive algorithms to process
the speckle images. We employ a set of filters to produce better discrimination
of the results as visually judged. This approach is a cheap and relatively
simple non-destructive and non-invasive procedure that could be extended to
other painted objects or subsurface hidings of archaeological interest, as well
as, to other dynamic speckle experiments.
