21 November 2016

GIGAmacro sample preparation: 3 techniques

Posted by Callan Bentley

Here are three pairs of GIGAmacro images to illustrate a few techniques I’ve used in preparing the samples and the images. The image pairs here illustrate the effects of transparent acrylic coatings, pressure-washing, and post-imaging clean-up in Photoshop.

Let’s begin with a meta-ignimbrite of the Catoctin Formation, cut with a rock saw and polished using a handheld grinding wheel with diamond grit pads, and then with one of the two sides, the second one in this set, sprayed with a layer of clear acrylic “paint.”
Link GIGAmacro by Callan Bentley

Link GIGAmacro by Callan Bentley

Here’s a mylonite, before and after being pressure-washed:
Link GIGAmacro by Callan Bentley

Link GIGAmacro by Callan Bentley

Here’s a pair to show the effects of digital clean-up in Photoshop after the image has been stitched together. Both show a set of three fossils (Khufus, Turitella, and Dentalium) from the Sunken Meadow Member of the Yorktown Formation in Virginia’s Coastal Plain. In the first, a layer called the “alpha channel” exists, automatically generated by the image stitching software I used, Kolor AutoPano Giga, producing the irregular white mess at the top of the image. In the second, I’ve deleted the alpha channel and also deleted many of the white scraps of shell debris lying on the black velvet backdrop.
Link GIGAmacro by Callan Bentley

Link GIGAmacro by Callan Bentley

I’d be happy to answer any questions you might have about any of these techniques. I’d also be eager to read your feedback on the merits of the different ‘treatments.’