{"id":16267,"date":"2026-09-08T14:03:42","date_gmt":"2026-09-08T18:03:42","guid":{"rendered":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/nasa-technique-for-manipulating-satellite-photos-now-reveals-ancient-images\/"},"modified":"2026-09-08T14:03:42","modified_gmt":"2026-09-08T18:03:42","slug":"nasa-technique-for-manipulating-satellite-photos-now-reveals-ancient-images","status":"publish","type":"post","link":"https:\/\/zobi.alcowep.com\/bourtagshdrevxnls658739\/nasa-technique-for-manipulating-satellite-photos-now-reveals-ancient-images\/","title":{"rendered":"NASA\u00a0Technique for Manipulating Satellite Photos Now Reveals Ancient Images\u00a0\u00a0"},"content":{"rendered":"

NASA\u00a0Technique for Manipulating Satellite Photos Now Reveals Ancient Images\u00a0\u00a0<\/h2>\n

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Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n
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Jon Harman poses in front of an example of the Rancho Bernardo style of Native American artwork that\u2019s barely visible until Dstretch is applied.\u00a0<\/div>\n
Credit: Jon Harman\u00a0<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

High in\u00a0the central tower in the ancient Cambodian temple\u00a0of\u00a0Angkor Wat, paintings depict horseback riders and a traditional musical ensemble.\u00a0Thousands of visitors pass these images\u00a0daily\u00a0without noticing, because\u00a0they\u2019re\u00a0faded to the point of invisibility.\u00a0<\/p>\n

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They were discovered\u00a0between 2010 and 2012, along with about 200 other paintings throughout the complex, by an\u00a0archaeologist using a method conceived at NASA\u2019s Jet Propulsion Laboratory in Southern California.\u00a0<\/p>\n

The technique, known as decorrelation stretch, heightens contrasts in digital imagery, making\u00a0features easier to spot.\u00a0It\u00a0is\u00a0especially\u00a0popular\u00a0for studying ancient rock art,\u00a0partly\u00a0due to the chance intersection of one man\u2019s hobby with his professional background.\u00a0<\/p>\n

Around 2005,\u00a0rock art enthusiast Jon Harman\u00a0saw\u00a0NASA\u00a0images depicting the Martian surface with and without the application of decorrelation stretch. Seeing how much detail the technique revealed,\u00a0Harman, now retired in Pacifica, California,\u00a0understood the implication for studying ancient, faded images.\u00a0<\/p>\n

He also worked\u00a0in medical imaging. \u201cI Googled it and found a NASA paper that explained how to do the algorithm,\u201d he said. \u201cI knew from my medical imaging experience that I could do it, so I did.\u201d\u00a0<\/p>\n

The paper was written in 1996 by Ronald Alley, a JPL employee developing\u00a0applications\u00a0for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a Japanese\u00a0imaging\u00a0instrument on NASA\u2019s Terra satellite.\u00a0One of\u00a0Alley\u2019s former supervisors\u00a0at JPL\u00a0had\u00a0coinvented decorrelation stretch, and Alley had recognized its potential for gleaning information from ASTER imagery.\u00a0\u00a0<\/p>\n

Harman made his plug-in for use with ImageJ,\u00a0an open-source program developed by the National Institutes of Health.\u00a0\u00a0<\/p>\n

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