At the central tower of Cambodia’s Angkor Wat temple, there are paintings depicting mounted horsemen and traditional musicians that went unnoticed because they had faded. Archaeologists identified these works between 2010 and 2012, along with approximately 200 other paintings throughout the complex, using the “decorrelation stretch” method developed at NASA’s Jet Propulsion Laboratory in Southern California. The technique, which enhances contrast in digital images, is used particularly to examine faded rock art.
Rock art enthusiast and medical imaging specialist Jon Harman developed the Dstretch plugin around 2005, drawing on a 1996 NASA paper after seeing details revealed by the method in images of Mars. The paper’s author was JPL employee Ronald Alley; Alley had examined the method’s potential for ASTER, the Japanese imaging instrument aboard NASA’s Terra satellite. Harman created the plugin for the open-source ImageJ program developed by the National Institutes of Health.
Dstretch has been used at San Borjitas Cave in Mexico, as well as at sites in Norway, Egypt and Canada; it has also helped examine buried Ancient Greek structures and tattoos on mummified human remains. Harman handles approximately 200 requests a year. The smartphone applications he created around 2010 have been downloaded thousands of times.
Why it matters
The significance of this development lies in making traces of cultural heritage that cannot be distinguished with the naked eye available for researchers to examine through an image-processing approach developed for space research. Dstretch’s operation on the open-source ImageJ makes it possible for specialists in different fields to use the method without relying solely on the hardware of major institutions; its applications in archaeology, rock art, buried structures and mummies demonstrate the scope of this transition. The process also reveals that methods can be transferred between medical imaging and archaeological documentation. However, it remains unclear how digitally enhanced details will be verified against the original images in the field and to what extent this approach will alter the interpretation of artifacts.
Background
NASA is not a new name in the FikirPilot archive: we have published 23 news reports mentioning this name in the past 90 days; the latest is dated September 4, 2026.