Technique for Manipulating Satellite Photos Now Reveals Ancient Images (2025)
https://dstretch.com/DecorrelationStretch.pdf https://www.nasa.gov/technology/tech-transfer-spinoffs/nasa-... Comments URL: https://news.ycombinator.com/item?id=49645437 Points: 292 # Comments: 46
Ancient paintings in the Cambodian temple Angkor Wat, once faded and nearly invisible, have been revealed using a technique called decorrelation stretch. Developed at NASA's Jet Propulsion Laboratory, this method enhances contrasts in digital imagery, making subtle details more apparent. Originally used for satellite imagery, it has since become widely used for studying ancient rock art due to its ability to clarify faded images.
Jon Harman, a Singaporean archaeologist, discovered the technique in the 1980s while attending rock art field trips. Intrigued by the mystery of ancient symbols, he learned the method and developed a plug-in called Dstretch, which later became available as Android and iOS apps. The technique, based on the Karhunen–Loève Transform, involves diagonalizing color matrices and mapping original colors to a wider range.
Harman's work has been instrumental in uncovering hidden images in rock art worldwide, including a new yellow figure in a Norwegian sun motif.
Written by urgent.news from Hacker News Best's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
