Instruments in the former study.

<p>All were violins, except Borman1995, viola.</p

Correlation of density measurements between the CT scanners of Leiden and New York City (NYC).

<p>Correlation of density measurements between the CT scanners of Leiden and New York City (NYC).</p

Comparison of the median density between modern and antique back and top plates from this study.

<p>Error bars indicate median values and the 95% confidence intervals.</p

Density maps in gram/liter of the back plates.

<p>Density maps in gram/liter of the back plates.</p

Geographical distribution of the antique instruments studied.

<p>Geographical distribution of the antique instruments studied.</p

Graph comparing the median density by country of the back and top plates and summed modern instruments.

<p>Country-Quantity: I-1, Italy (other than Cremona); N-6, the Netherlands; F-1, France; GA-5, Germany/Austria; Gdg-3, Italy (Guarneri del Gesu); S-2 Italy (Stradivari); M-12, Modern instruments.</p

Example of a distribution of densities in a region of interest in a top plate, from which the median value and differential is calculated.

<p>Example of a distribution of densities in a region of interest in a top plate, from which the median value and differential is calculated.</p

Instruments in the current study.

<p>All were violins, except PR1710, viola.</p><p>Note: Due to changes in political boundaries, “origin” in our usage denotes the current geopolitical boundary of the city of origin. NL: the Netherlands, USA: United States of America.</p

Correlation between the number of grain lines/cm in spruce tops and the apparent density differential; Resolution/contrast test by the Catphan® phantom showing a similar shape.

<p>Correlation between the number of grain lines/cm in spruce tops and the apparent density differential; Resolution/contrast test by the Catphan® phantom showing a similar shape.</p

Protocol optimization.

<p><b>a.</b> Calibration wood-set composed of different wood sample pieces; #'s 1–5,16, picea abies, #'s 6–10,15, acer pseudoplatanus, #11 fagus grandifolia, #12 acer glabrum, #13 populus albus, and # 14 juglans nigra. <b>b.</b> Comparing differences in metal artifacts from the metal strings in a CT scan of a violin; <b>c.</b> Images of the first calibration wood piece, obtained from the four candidate filters.</p