Jump to content
  • Sign Up
×
×
  • Create New...

[NASA] NASA Technique for Manipulating Satellite Photos Now Reveals Ancient Images  

SpaceMan

By SpaceMan,
in World News

 Share

Recommended Posts

  • Diamond Member
SpaceMan Hunter

SpaceMan 0

Posted
  • Diamond Member
Posted

3 min read

Preparations for Next Moonwalk Simulations Underway (and Underwater)

This is the hidden content, please
Jon Harman poses in front of an example of the Rancho Bernardo style of Native American artwork that’s barely visible until Dstretch is applied. 
Credit: Jon Harman 

High in the central tower in the ancient Cambodian temple of Angkor Wat, paintings depict horseback riders and a traditional musical ensemble. Thousands of visitors pass these images daily without noticing, because they’re faded to the point of invisibility. 

They were discovered between 2010 and 2012, along with about 200 other paintings throughout the complex, by an archaeologist using a method conceived at NASA’s Jet Propulsion Laboratory in Southern California. 

The technique, known as decorrelation stretch, heightens contrasts in digital imagery, making features easier to spot. It is especially popular for studying ancient rock art, partly due to the chance intersection of one man’s hobby with his professional background. 

Around 2005, rock art enthusiast Jon Harman saw NASA images depicting the Martian surface with and without the application of decorrelation stretch. Seeing how much detail the technique revealed, Harman, now retired in Pacifica, California, understood the implication for studying ancient, faded images. 

He also worked in medical imaging. “I Googled it and found a NASA paper that explained how to do the algorithm,” he said. “I knew from my medical imaging experience that I could do it, so I did.” 

The paper was written in 1996 by Ronald Alley, a JPL employee developing applications for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a Japanese imaging instrument on NASA’s Terra satellite. One of Alley’s former supervisors at JPL had coinvented decorrelation stretch, and Alley had recognized its potential for gleaning information from ASTER imagery.  

Harman made his plug-in for use with ImageJ, an open-source program developed by the National Institutes of Health.  

This is the hidden content, please
This is the hidden content, please
before
after
This is the hidden content, please
This is the hidden content, please
beforeafter
This is the hidden content, please
This is the hidden content, please
before
after

Before and After

Dstretch applied to Cave of San Borjitas in Baja California, Mexico

CurtainToggle2-Up
Image Details
As Jon Harman was developing the Dstretch plug-in, he applied it to this image from the Cave of San Borjitas in Baja California, Mexico. When the yellow figure appeared in the middle of the picture, he knew he had something useful. Credit: Jon Harman 

He said he fulfills about 200 requests for Dstretch per year. Around 2010, he also created smartphone apps that use a shortcut to mimic decorrelation stretch. The apps have been downloaded thousands of times, and papers have been published describing Dstretch’s usefulness in archaeology. 

It has been used to spot and clarify imagery at ancient sites under a cliff in Norway, in an Egyptian tomb, at a park in Canada, and in many other locations. It has also helped archaeologists find buried remains of ancient Greek buildings and examine tattoos on mummified human remains, among its non-rock-art applications.  

Harman said he was not surprised Dstretch found wide use in the rock art community. “But I’ve been surprised by a lot of the different applications people have found. So that’s been cool.”  

Share

Details

Last Updated
Sep 08, 2026

Related Terms

Explore More

This is the hidden content, please

0

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing

  • Vote for the server

    To vote for this server you must login.

    Jim Carrey Flirting GIF

  • Recently Browsing   0 members

    • No registered users viewing this page.

Important Information

Privacy Notice: We utilize cookies to optimize your browsing experience and analyze website traffic. By consenting, you acknowledge and agree to our Cookie Policy, ensuring your privacy preferences are respected.

  I accept