Download Vortragstitel - Pattern Recognition Lab

3-D Reconstruction of
Historical Documents using
an X-Ray C-Arm CT System
D. Stromer, G. Anton, V. Christlein, P. Kugler and A. Maier
22.11.2016
Pattern Recognition Lab (CS 5)
Outline
● Introduction
● Materials and Methods
● Results
● Discussion & Outlook
2
Digitization of Documents
● Scanned page-per-page with camera
● ~3000 pages per hour (Treventus)
Not applicable for some kinds of historical documents
because page-turning process would damage them
3
Historical Writings
● Paper

Cellulose 𝐶6 𝐻10 𝑂5 with density 1.5
𝑔
𝑐𝑚³
● Iron gall ink

Used for historical documents:

‘Declaration of Indepence‘

Goehte‘s ‘Faust‘

Mozart‘s ‘The Magic Flute‘

Rembrandt

……

Iron(II) sulfate heptahydrate 𝐹𝐸 𝑆𝑂4 ⋅ 7 𝐻2 𝑂 with density 1.89

Metallic particles
→
𝑔
𝑐𝑚³
X-Ray imaging
4
State-of-the-art
● Phase contrast method (Synchrotron)
 Mocella et al [1]:
 Deckers and Glaser [2]:
Reconstructing erased or overwritten iron gall ink writings
[1] V. Mocella, E. Brun, C. Ferrero, and D. Delattre, “Revealing letters in rolled herculaneum papyri by x-ray phase-contrast
imaging,” Nature communications, vol. 6, 2015.
[2] L. Glaser and D. Deckers, “The basics of fast-scanning xrf element mapping for iron-gall ink palimpsests,” Manuscript
cultures, vol. 7, no. PUBDB-2015-06320, pp. 104–112, 2014
5
Our approach
● Artis zeego robotic X-Ray C-arm System with Cone Beam Geometry
Siemens Artis zeego
Cone Beam Geometry
6
Simulations
● CONRAD Framework
● Axis-of-rotation orthogonal to the front cover
detector
source
7
Simulations
● CONRAD Framework
● Axis-of-rotation orthogonal to the front cover
● Polychromatic phantom consisting of cellulose, ink and air
Spectral absorption plot for iron gall ink and cellulose
● Model consisting of 10 pages with page thickness of 1 𝑚𝑚
● Reconstruction with FDK algorithm
8
Real data reconstruction
● Handmade paper with iron gall ink writings
● Wooden holder for fixing and flattening the pages
● Bilateral filtering after reconstruction
9
Simulation Results
Original Phantom
Reconstruction
10
Page flattening
Phantom rotation for
simulating warped page
Writing to 2D image
Manual segmentation
of a page
11
Real Data Results
12
Original
X-Ray
Overlap
Real data reconstruction of third page showing the letter ‘B‘
13
Original
X-Ray
Overlap
Real data reconstruction of fourth page showing the letter ‘B‘
14
Applied flattening algorithm
Original
X-Ray
Overlap
Real data reconstruction of sixth page showing the letter ‘M‘ after applying
the introduced flattening algorithm
15
Discussion & Outlook
Reconstruction of iron gall ink is possible but:
● X-Ray System adaption

kV reduction, pixel shift
 Collimation
● Reconstruction algorithm

Iterative algorithms: SART, TV
 Filtering
● Multimodality

Combination with different CT trajectory
 Terahertz
16
Questions ???