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 16th century German Reformation text written by Martin Luther and is volume 8 of an 8 volume set entitled Aller Bücher und Schrifften des thewren, seligen Mans Gottes Doct. Mart. Lutheri ..., which is part of UCL's Archives and Rare Books Library's collection.   The binding is most likely age-hardened alum-tawed leather (though possibly vellum) on wooden boards with embossed paneled decoration.  However, most of this paneled decoration, which includes figures, Latin inscriptions and other decorative elements, is not easily visible under normal illumination.  Therefore the Preservation Lab decided to do a highlight RTI capture sessions for both the upper and lower covers.  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/  

In this video capture of the lower (back) cover of this Martin Luther text we explore the surface shape and color of the binding by actively relighting the object and using various modes built within the RTI Viewer.  The video begins with the default lighting of the object and as the light position moves around the cover you are given a variety of raking illumination views of the surface.  Then we switch to the Specular Enhancement mode, which offers the option to remove the color from the image and to add specularity to a surface which has very little specularity, thus accentuating aspects of the panel detail.  When we zoom in we better see the detail of these ornate panels.  You can also see the deterioration and loss of detail caused by surface abrasion (Think about how books are often scooted across a table...that causes surface abrasion to the lower cover.  Now take a book that is nearly five centuries old and imagine what that book has endured).  It is interesting to compare the detail of the upper/front cover with that of the back.  The most obvious evidence of surface abrasion and loss of embossed detail is the central figure (Martin Luther?) who is much move visible on the upper cover versus the lower cover.

Next we will pan out and examine the Normals Visualization mode with allows the human eye to better see what is convex and concave on the surface of the cover.  For example, here you can better see the loss of detail in the central figures features, such as his nose, eyes, and hat.  Then we pan to the area just below this figure and you'll notice a large U-shaped area of loss caused by surface abrasion.

Next we switch to the PTM module where we explore the Diffuse Gain mode.  This mode is ideal for visualizing surface abrasions and losses.  We zoom in to highlight some scratches in the skin and to the left you will notice a small circular deformation in the alum tawed skin, near the clasp.  When we pan down further you can better see this large area of scuffed skin.  Next we switch to the Normal Unsharp Masks mode which further exaggerates these surface deformations, while also making decorative elements of the panel much more visible and legible.

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