Tag Archives: Martin Luther

Fun with PhotoDoc – RTI Viewer Video (Edition 6)

In my last “Fun with PhotoDoc” post I discussed the my recent RTI training with Cultural Heritage Imaging at Yale University.  If you missed that post you can check it out here.  In that post I discussed our first RTI capture session on a book entitled, Aller Bücher und Schrifften des thewren, seligen Mans Gottes Doct. Mart. Lutheri …, which is part UC’s Archives & Rare Books Library’s collection and is the eighth volume in an eight volume set.   The binding is most likely age-hardened alum-tawed leather (though possibly vellum) on wooden boards with embossed paneled decoration that is barely visible under normal illumination.  In that first RTI blog post I shared some snapshots of the various RTI modes you can explore within the RTI Viewer software, but I knew that I ultimately wanted to create a video capture of the RTI Viewer in action.  I was finally able to do that using a free software called TinyTake.

This video can also be viewed through UCL Media Space:  https://stream.libraries.uc.edu/media/AllerBucherUndSchrifften_i17632730_VideoCaptureRTI/1_s13c9opc

In this video we explore the following modes built within the RTI Viewer as the light position is moved around the object:

  • Default Mode (HSH)
  • Specular Enhancement Mode with color removed (HSH) – notice the “1571” inscription that becomes more apparent.  This volume was printed in 1568, and we believe that 1571 was when the publication was bound.
  • Normals Visualization Mode (HSH) – allows the human eye to better determine is convex and concave on the surface of the cover.
  • Diffuse Gain Mode (PTM) – This mode is ideal for visualizing surface abrasions and losses. Take notice of the “ID” inscription that becomes more visible, and when we switch back to the default mode you can see that this “ID” inscription is virtually invisible to the naked eye.

I have to say, Catarina and I really enjoyed the capture process for this binding, but when we found that “ID” and then looked at the physical binding and could barely see anything…we were kind of giddy!  I’m hoping to create more RTI Viewer video captures like this as we carry out more RTI capture sessions for collection materials.  When I do, I will make sure to share them here.

Jessica Ebert (UCL) – Conservation Technician

Fun with PhotoDoc – RTI (Edition 5)

At the beginning of April I was lucky enough to attend a RTI (Reflectance Transformation Imaging) workshop offered by Cultural Heritage Imaging (CHI) at Yale University.  CHI is a non-profit organization  that shares and teaches RTI and Photogrammetry technology with cultural heritage institutions around the world.  The class I attended was a 4-day NEH grant sponsored course taught by three RTI experts from CHI, and it was amazing!

This is a composite image of all the highlight points from one RTI section. The software uses these highlight points to map the surface shape and color of your object.

So, what is RTI?  CHI describes it on their website as “a computational photographic method that captures a subject’s surface shape and color and enables the interactive re-lighting of the subject from any direction”.  For highlight RTI, which is the least expensive and most accessible method for most institutions and what I was taught in the class, you basically take a series of 36 to 48 images of an object where everything is constant (settings and position of objects, camera and spheres) except for the light position.  With a reflective black sphere (or 2) set up next to your object, you move you light source around the object at varying angles.  Then, you take that set of images and plug them into the free RTI software provided by CHI and the algorithm detects the sphere(s) and the highlight points (from your light) captured on the sphere(s) and voila!…you have an fun and interactive way to look at your object’s surface texture.

Before I attended this fantastic training opportunity, our conservator and I knew right away what the subject of our first capture would be when I returned…a 16th century German Reformation text by Martin Luther with a highly decorated cover that is practically invisible under normal illumination.

Here’s a time lapse video of our first (and second) capture in the Lab…

That day (Tuesday) were were able to capture the upper and lower covers of the Reformation text (from ARB), the original silk cover from a 17th century Chinese manuscript (from Hebrew Union College) and an illuminated page from a German vellum prayer book (from PLCH).  And here our some snapshots of our results from two of those captures (click on the thumbnails for a larger view of the image)…

This possibly 13th century German Prayer Book has a full stiff vellum binding and an illuminated first page.  The varying modes highlight condition issues like worn/abraded parchment and flaking gold illumination, as well as the overall surface texture of the illumination.

I hope you’ve enjoyed getting a little sneak peek into RTI.  I will be demoing and discussing in further depth this afternoon from 1:30 to 3pm at the Lab’s annual Preservation Week Open House.  I also hope to do more RTI captures/processes in the future and share them here.

Jessica Ebert (UCL) – Conservation Technician