In collaboration with the Cambridge University, the Gower manuscript R.3.2 in the Trinity College was multi-spectrally imaged with a 8-channel multi-spectral camera. The whole procedure of producing the ready-to-use data is composed of two steps described as follows.
Step 1: Data Acquisition
The focus of this step is on obtaining the raw image data of the pages of the manuscript R.3.2, as well as some extra data, which shall be used for calibration purpose in the following step of data processing. Following the process below, we acquired the data.
1) Set the manuscript in correct position on book cradle and adjusted camera position and focus, then removed book.
2) Adjusted light position to obtain homogeneous lighting across a white card laid across the entire field of view. Light levels at the object are approximately 600‐650 lux.
3) Adjusted exposure for each filter by checking signal levels on black and white reference standard (white fluorilon, black spectralon). The maximum exposure allowed by the imaging system is 2000 ms, which does not allow to satisfactorily maximize signal levels for a couple of the filters used, especially filter 7 (CWL 375 nm).
4) Captured image set for white card and a “dark” image set (captured with lenscap on).
5) Acquired reflectance spectra as well as image set of black and white reference standards placed within field of view of camera.
6) Captured image sets for white reference standard placed in 58 different positions in order to cover entire field of view of camera.
7) Captured image sets (bit-depth: 8) for each page in the book.
The below shows the list of filters and the exposure used for each filter.