Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/jplnews/0988.ZIP/0988.PR

Text File | 1993-04-23 | 5KB | 194 lines

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 9ll09. TELEPHONE [phone]


FOR RELEASE MONDAY, MAY l0, l982


          Space scientists at JPL working with art
conservators

at the Los Angeles County Museum of Art have developed a new

technique for separating paintings hidden beneath master
works.

          The effort resulted in the first successful use of

image enhancement techniques to separate X-ray images of
paintings

where two or more works exist on the same surface, according
to

museum officials.

          The technique, derived from computer-processing of
photo-

graphs from NASA's unmanned spacecraft, will allow art
conservators

and museum curators to better evaluate earlier compositions
often

found underneath easel paintings.

          William R. Leisher, head of conservation at the Los

Angeles County Museum of Art (LACMA), asked JPL investigators

to separate and enhance a painting found to exist beneath the

17th century oil painting "The Crucifixion," by an
unidentified

Flemish painter. î
          Astronomer Dave Glackin and scientist Don Lynn,
both

image processing specialists, and computer analyst Raim
Quiros,

in collaboration with Jium Druzik and Dr. Pieter Meyers of
the

museum, developed computer programs for subtracting the top
painting

from the botto , so that the hidden painting may be seen in
detail.

          "The Crucifixion," painted on paper, shows Jesus
Christ


being lowered from the cross by a group of followers.  The
bottom

painting, painted directly on the 16-by-24 inch wooden panel,

shows a scene of a man and a woman seated at a table.
The two are dressed in l7th century clothing, and the room is

lighted by sunlight shining through a window.

          Art conservators commonly use X-ray photography to

examine paintings.  The X-ray photos may often show that
paintings

or sketches exist beneath a top painting, but the works are

not automatically delineated. The two works usually are fused
in

an X-ray photo and appear as a blurred, double image.

          "What we sometimes find is a completely different

composition underneath," said Druzik, associate conservator

at the museum.  When that happens, he said, "there will
always

be a question in the curator's mind as to whether or not an

unknown masterpiece exists under the top painting layer." î
          In order to separate the two images, the JPL team

first designed computer programs to minimize the appearance
of

the grain pattern of the wood on which the original work was

painted.

          Next, a photograph of the top painting was matched

with the X-ray image.  Any brushstrokes from the X-ray
version

that matched the top painting were subtracted.  Consequent

subtractions removed most traces of the top painting, while
the

remaining bottom painting was computer-enhanced to bring out
detail.

          The pioneering development of the painting
subtraction

technique could lead to future systems designed uniquely for

discerning and separating multiple X-ray images of paintings

with designs under the surface.  Such systems, said Druzik,

"will be another invaluable tool for conservators and
curators."


          "This project is a good example of the applications
of space technology to other problems of great public
interest,"

said Dave Glackin of JPL.  Glackin and Kurt Liewer of JPL,
working

with LACMA conservators, are undertaking a new task, using a

high-resolution spacecraft photography system and JPL's image

processing facility to study the condition of the museum's î
_C_o_d_e_x__H_a_m_m_e_r, a treatise on
the nature of water by Leonardo da

Vinci.  Results from the project, supported by a grant from

the Armand Hammer Foundation, should determine how to best

preserve the works.

          Future applications of computer processing to art

conservation might include techniques to date paintings by

determining the age of wood on which compositions were
painted.

Dendrochronology, the science of dating wood based on the

number and character of tree rings, usually requires shaving

wood away from the edge of the original wood panel.  Computer

enhancement of the wood grain of a panel would eliminate the

need to remove original support material in order to date it.

          The $35,000 painting subtraction project was funded

by the Caltech President's Fund.   JPL is operated for NASA
by

Caltech.



#988
5/l0/82MBM