This is video capture that explores highlight Reflectance Transformation Imaging (RTI) using the RTI Viewer (provided by Cultural Heritage Imaging - free downloadable software for view RTI captures).  This is a small stiff board parchment binding with a parchment textblock.  The text is a handwritten manuscript with an illuminated first page.  There are several processes for illuminating manuscripts, so we decided to perform a highlight RTI capture of the illuminated first page to better understand the process of illumination.  Though the exact process is not known, even after RTI was performed, the RTI capture revealed that the gilding is raised from the surface of the parchment which indicates it may be applied over a white gesso.  To learn more about RTI and this particular capture session visit the Lab's blog post on the subject: http://blog.thepreservationlab.org/2017/04/fun-with-photodoc-rti-edition-5/  

The video begins by exploring the default mode, which allows us to actively relight the surface of the object capturing both normal illumination views of the page, as well as raking illumination views.

Then we switch to the Specular Enhancement mode.  Here you can better make out the losses of gild on the oversized, first letter.  You can also see more clearly that the gilding is raised from the surface of the parchment, notice the gilding below the oversized letter and the flower near the fore edge.  The Normals Visualization mode also helps to show off how the gilding is elevated from the parchment page.

Next we switch to the PTM module and explore the Diffuse Gain mode to highlight the gilding further, as well as to explore the areas of rough surface texture which helps to show that parchment is an animal skin.

This RTI capture session was performed by Catarina Figueirinhas and Jessica Ebert .