Tag: tools

The polynomial texture map of Sinai 349.
Archaeology

Tools for Modern Epigraphy (Part 2)

Last week, we touched upon three new technologies that have revolutionized the field of epigraphy.  These technologies have changed the way epigraphers see their inscriptions.  Today, we will introduce another four technologies that have changed epigraphy in the 21st century.

Multi-Spectral Photography

With the proliferation of digital cameras, many people now have a second (or third) DSLR camera just lying around.  As epigraphers, we don’t need to have those old cameras go to waste.  Instead, we can send them to a conversion lab to have them converted for multi-spectral photography.

Most of the photodiodes in DSLR cameras are already sensitive to infrared and ultraviolet light.  This is normally a bad thing as these light wavelengths cause false colors with visible light photography.  So camera manufacturers add filters over the photodiode to screen out infrared and ultraviolet light.

By removing the infrared filter and adding a visible light filter, you can get an infrared camera.  Infrared cameras are useful for infrared luminescence.   By removing the ultraviolet filter and adding a visible light filter, you can get an ultraviolet camera.   Ultraviolet cameras are useful for detecting the pigments and minerals that fluoresce in the ultraviolet spectrum.

Multiple Light Photography

With advances in photography has also come advances in photographic setups and procedures to capture difficult to obtain information.  One of the most rudimentary of these is the multiple light setup.  With multiple light photography, the camera is kept in one position and the light sources are moved around the piece in progressive small angles.  Typically this this done in a 180 degree arc.

The advantage of this is that it can capture the fine details in the recesses of the piece, which can be exposed just by moving the light to another position.

Polynomial Texture Maps

This technique scans the surface of an artifact and recreates the surface of an object as a high resolution map of polygons.  Using this you can see the object from various angles and shine artificial lights upon the map to see the details.

Furthermore, the contrasting topography of a piece can be emphasized so that you can detect small details in the texture of the piece.  PTMs are often the next best thing to being able to see an object in person.  In the featured photo above, we see two images of Sinai 349 with the polynomial texture map to the right.

Strobe Lighting

Sometimes, none of the above techniques are all that helpful.  And the epigrapher just has to examine an artifact in person.  Perhaps, the contrast between the inscription and the matrix is too low.  Or maybe the inscription is too shallow to see or photograph clearly.  There is one more advanced technique that is helpful.  While not strictly speaking new, strobe lighting has recently found new usefulness in epigraphy.

When you look at a stela with only discrete color differences between inscription and matrix, your vision adjusts faster than your brain can figure out what you’re seeing. In a tenth of a second, your visual cortex becomes saturated and those discrete color differences between inscription and matrix wash out.

What strobe lighting does is prevents your visual cortex from saturating. This way you can continue to see the fine differences between the inscription and stone matrix. The net result is that visual features not seen previously begin to emerge. 

 

 

A split photo of the petroglyphs from Stein Park. The right half is enhanced by DStretch.
Archaeology

Tools for Modern Epigraphy (Part 1)

The field of epigraphy has under gone a silent revolution over the last decade.  The problem of epigraphy has always been the same.  That is, being able to read inscriptions that are hard to see.  The process was laborious with readers taking weeks to carefully examine and untease a difficult to read inscription.

Today, while reading an inscription still can take weeks to unlock, the following advanced technologies transformed epigraphy into a more scientific endeavor.  The difference is not so much how long things take, but that epigraphers are now able to engage ever more difficult inscriptions.

In fact, the way that epigraphy is done today would hardly be recognizable to the epigrapher of a decade ago.  Gone are the days of crudely magnifying blurry photographs taken on site.  A host of new technologies now exist that would put the space shuttle to shame.  Today’s bog will give the briefest introduction to three of these tools.

Digital Photography

Digital photography is the foundation of 21st century epigraphy.  Even as late as the 1990’s, black and white film photography was preferred over digital images because of the detail captured by film.  Today, that is no longer true.  Even older DSLR cameras can capture an image resolution that exceeds many film photos.  But more importantly,  DSLR color images can capture color information that is simply not preserved by film photography.

Furthermore, in the old days, if you wanted to manipulate an image, you needed to digitize a photograph with a scanner.  Even the best scanners resulted in some image degradation.  A DSLR camera can create a RAW image that preserves what the camera sees directly from the camera sensor.  More image data means a greater capacity to extract information from an image.

Photoshop

Photoshop is the Swiss Army knife of the epigrapher.   And the ability of Photoshop to manipulate photographic information is practically limitless.  Photoshop can enhance a single image, and it can composite many smaller images together.

With Photoshop, the epigrapher can amplify the color curve of a photo.  This can make a photograph with low contrast easier to read.  Photoshop can also convert a color image to black and white using existing color information.  This can provide not just one, but many black and white images that can show different aspects of the same photo.

DStretch

One of the more interesting advances in the last decade has been the invention of DStretch.  The developer of DStretch sells the program as a plugin used with ImageJ, a free imaging software package.   The plugin pulls the colors of red ochre from an image and allows the epigrapher to see the image more clearly.  For example, I used DStretch to make the petroglyphs from Stein Park, BC (photo by Sebastian Rakowski) easily seen.

While originally designed for prehistoric anthropologists to extract hard to read petroglyphs from rock faces, others in the fields of archaeology and epigraphy have found the tool exceptionally useful.   Roland Enmarch has used DStretch to read inscriptions at the quarry site of Hatnub.  I have also found it useful to separate out damage from inscription in one of the early alphabetic inscriptions from Serabit el-Khadim.