Computational Photography Techniques for Historical Sites and Artifacts

Instructors: Carla Schroer and Mark Mudge, Cultural Heritage Imaging

Monday December 2, 2024

Through lectures, demonstrations, and discussions, this workshop provides a condensed overview of computational photography and its application to cultural heritage. Computational Photography extracts and synthesizes information from image sequences to create new digital representations containing information not found in any single image in the sequence. This workshop offers an extensive introduction to the technologies, software, photographic equipment, and methods for Reflectance Transformation Imaging (RTI), and photogrammetry.

RTI creates scientific digital representations of an imaging subject’s shape and color. These digital representations are generated from image sequences where the light illuminating the photo’s subject is moved to a new location for each photograph. The lighting information from this image sequence is mathematically synthesized into an RTI image.

Photogrammetry refers to the practice of deriving 3D measurements from photographs. It can be used for documenting 3D subjects, monitoring changes to these subjects over time, and a wide range of other uses. Photogrammetry, when done correctly, creates accurate and measurable 3D models on a wide range of scales. We also explore how these photographic data sets and the digital representations they produce can be archived and confidently reused by others both now and in the future. The workshop will also describe open-source tools for the recording and archiving of photogrammetry and RTI contextual and process metadata using the Digital Lab Notebook (DLN).

Numerous case studies and examples will be shown. We will also share our experiences working with local and indigenous communities enabling them to adopt computational photography techniques to document their own cultures.

Reflectance Transformation Imaging (RTI): Looking at fine surface details

Instructors: Carla Schroer and Mark Mudge, Cultural Heritage Imaging

Tuesday December 3, 2024

Using RTI, the subject’s shape and color can be examined by interactively re-lighting the subject from any direction and applying mathematical enhancements within an RTI software-viewing environment. RTI is used on a wide range of subjects, including inscriptions, rock art, manuscripts, engravings and paintings.

The core of this workshop is a demonstration of capturing an RTI photo set. This is followed by a hands-on opportunity** to process an RTI image set in the open source RTI software pipeline, including RelightLab. Results will be viewed in the desktop RTIViewer and a web-based viewing environment, based on OpenLime. We will also look at the metadata and archive package for an RTI image in the Digital Lab Notebook (DLN).

**Participants should bring a laptop (Mac or PC) in order to participate in the hands-on portion of the workshop. The software is open source, and links for downloading and installing the software will be provided prior to the workshop, along with a download link to an example image set.

Biography

Carla Schroer is a co-founder and director of Cultural Heritage Imaging (CHI) a non-profit corporation that develops and implements new imaging technologies for cultural, historic and artistic heritage and scientific research. Cultural Heritage Imaging (culturalheritageimaging.org) has been active in the cultural heritage computational photography research community since 2002. Carla leads the training programs at CHI, along with working on field capture projects with Reflectance Transformation Imaging and photogrammetry. She also leads CHI’s software development activities. She spent 20 years in the commercial software industry, managing and directing a wide range of software development projects.

Mark Mudge is President and co-founder of Cultural Heritage Imaging. He has been involved in photography and 3D imaging for more than 30 years. He is a co-inventor, with Tom Malzbender, of the computational photography technique, Highlight Reflectance Transformation Imaging. He has published 15 articles and book chapters related to scientific imaging of cultural heritage material and its long-term preservation. He serves on several international committees, including The International Council of Museums' (ICOM) Documentation Committee (CIDOC).
 

Reveal the invisible

Instructor: Eric Joakim, PhaseONE

Tuesday, December 3, 2024

In this training session, we will discuss the basics of multispectral imaging and present a fully automated workflow that delivers perfect image stacks ready for subsequent analysis, whether in the studio or on location. We will run through the analysis steps and show how visual images can deliver scientifically valid data for research and investigation. We will work on objects by hands- on session showing what can be achieved using this method for investigating text, artworks and artefacts. Adding on after automated capturing process the valid data elaboration by statistical analysis like PCA, ICA and K-mean Cluster helps reveil invisible text parts & material residues.

Eric Joakim has worked with Phase One since early 1994, specialising in high-end digital capture systems for professional photographers and cultural heritage institutions. With extensive experience from the early days of scanning backs through to today’s high resolution instant capture solutions, and having worked in the reseller channel, distribution channel and directly for Phase One, Eric has seen every development that Phase One has brought to the market. Eric is a key member of the Cultural Heritage team at Phase One, and has for the past eight years been a driving force behind the development of the Phase One Rainbow Multispectral Imaging Solutions.
Contact: ejo@phaseone.com | https://www.phaseone.com

Multispectral Image Processing with Hoku

Instructor: Keith T. Knox, Early Manuscripts Electronic Library

Wednesday December 4, 2024

Multispectral imaging has been used to recover writing on palimpsests, i.e. erased and overwritten parchment manuscripts. Imaged properly, multispectral images can capture very small spectral differences between the different layers of writing. Over the last several decades, software algorithms have been developed that can detect and enhance these differences to reveal the erased writing. Bring your own laptop to this session to get hands-on experience with Hoku, a freely-available software package that is designed to detect, extract, enhance, and make visible the erased writing from a multispectral image data set. Given the size of these image data sets, a laptop with at least 16 GB of RAM is recommended. The latest version of Hoku can be downloaded from https://www.cis.rit.edu/~ktkpci/Hoku.html.

Keith T. Knox is the Chief Science Advisor for EMEL, the Early Manuscripts Electronic Library (emel-library.org), a non-profit organization dedicated to using digital technologies to make historical source materials accessible to the public. He is an imaging scientist with over 50 years experience in image processing. Keith spent 30 years working for Xerox Research in Rochester, New York, and 10 years working at the AMOS observatory on the island of Maui in Hawaii. For the last 30 years, Keith has been using and developing image processing methods to recover erased writing from manuscripts. Since 2015, he has been developing a portable, user-friendly image processing software package in Java, called Hoku. This package is freely available to the public for general use and runs on Windows, macOS, and Linux. Contact: ktkpci@rit.edu

Practical information

Venue

The training event will be held at the Norwegian University of Science and Technology (NTNU) in Gjøvik, Norway. It will be located at the Kobolt (K) Building.

Accommodation and Travel to Gjøvik

Symposium participants are responsible to arrange their own travel and accommodation.

Follow this link for information on how to get to NTNU in Gjøvik.

Accommodation options in Gjøvik are as follows:

• Quality Hotel Strand, Gjøvik
• Clarion Collection Hotel Grand, Gjøvik
• Gjøvik Hovdetun Hostel