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Hidden Art

In 1999, Texas Parks and Wildlife Department contracted with Robert Mark and Evelyn Billo of Rupestrian Cyberservices to conduct a photo documentation survey of the rock art in Hueco Texas Historic Site. The undertaking was massive. The results of their work—now compiled on 12 CDs—represent the most comprehensive record of the site's rock art available.

The crew photographed not only known rock art locations but also documented dozens of others that were previously unknown. Many of the pictographs were faded or covered with soot. Others had been almost obscured by graffiti or historic period paintings and inscriptions. Others were identified as simply faint traces of color. As Mark recounts the experience, "Each day, we found at least three or four new sites." Taking the photographs frequently entailed sliding under boulders and into small crannies between the rocks. Each pictograph was photographed with a color scale and using several different lighting applications. Additional information was noted on documentation forms, and the site recorded using GPS locational data.

Back in their laboratory, Mark and Billo use computer techniques based on global algorithms, including filters and histogram stretches, to digitally enhance the images and bring the paintings into greater detail. (See the Rupestrian Cyberservices website to learn more.)

Below are "before and after" images of some of the paintings "discovered" using these techniques at Hueco Tanks. Roll your cursor over the photographs to open the computer-enhanced image with the "hidden art."

Robert Mark squeezes into a tight spot to photograph a pictograph at Hueco Tanks. Photo by Rupestrian Cyberservices, courtesy of Texas Parks and Wildlife Department.