NEXT MEETING: Wednesday, October 20, 2021, online via Zoom: Our Featured Speaker will be our own Thatcher Rogers, research associate at the Jornada Research Institute, discussing "Becoming a 'Pueblo': Late Prehispanic Shifts in the Sierra Blanca as Viewed from Robinson Pueblo" - reflecting his investigations in the Northern Jornada Mogollon (Lincoln) area. As usual, hop online about 6:45 PM to get settled, and Thatcher will begin his talk at 7PM sharp.

NEXT FIELD TRIP = TBA - watch this space for details as they develop.

Navajo Culture On Mars!
MAREC Progress Report - Phase III

Meet D-Stretch: the Archaeologist's Friend

Picto 3 - natural Picto 3 - StretchSome avocational archaeologists have already learned of the fascinating technology of D-Stretch, aka decorrelation stretch, a digital imaging tool that was originally developed to enhance (i.e., "stretch") the color differences in aerial photographs. Today, this technology has become more widely used and user-friendly to boot. It is now an essential tool to analyze rock art images, especially ones too faint for the naked eye to see.

Picto 4- Stretch Picto 4- naturalThe two pairs of images you see on this page were taken by the GCAS's own Marglyph, alias Margaret Berrier. She has kindly given us permission to post them here so that we can all see how significant the D-Stretch enhancement can be. The left-most photos are her examples of natural, "naked eye" photos of rock art; and the brightly colored photos next to them reveal the same image in D-Stretch.

For many more images of rock art in D-Stretch as well as technical data, start at the D-Stretch home page itself.

In its most professional format, D-Stretch is a plugin to the Javascript program, ImageJ, that must be installed before D-Stretch can be used. Some of our more tech-savvy readers may be inclined to select this alternative. However, for the more casual of us avocational archaeologists who do not necessarily need high functionality, there's an app for that. Our GCAS President, the straightforward Kyle Meredith, opted for the straightforward app and reports: "...I looked up the app on Google Play for my android phone and ordered it. I think the price was $19.99. SO EASY!" Kyle adds that use of the D-Stretch app has a bit of a learning curve but it promises to be big fun for anyone interested in photographing and enhancing rock art in the field. Like all of us GCAS members who've spent a year itching for resumption of field trips.

If Joe Bob Briggs were into rock art, he'd say check it out.

/s/ webmaster


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