1 WEAVE MAP REPORT Officer and Laughing Girl Johannes Vermeer c. 1657-60 L06; accession number 1911.1.127 The Frick Collection C. Richard Johnson, Jr. Cornell University johnson@ece.cornell.edu William A. Sethares University of Wisconsin - Madison sethares@gmail.com August 2017 In this report, paintings by Vermeer are referred to by L-numbers, based on their numbering in W. Liedtke, Vermeer: The Complete Paintings, Ludion, 2008. The dates cited on this cover page span the range of dates estimated in the oeuvre catalogs by Wheelock (1997), Liedtke (2008), and Franits (2015) as compiled in the table at www.essentialvermeer.com/ references/dates.html.
Johnson and Sethares, Weave Map Report, August 2017 2 Summary This document applies spectral-based, automated thread counting to Officer and Laughing Girl (L06) by Johannes Vermeer and includes the following: 1. stitched x-radiograph of full painting 2. vertical thread density map 3. horizontal thread density map 4. vertical thread angle map 5. horizontal thread angle map 6. histograms of vertical and horizontal thread counts and angle maps 7. a listing of all close count matches (within ±1 th/cm in both directions for an H to H and V to V match or an H to V and V to H match) among Vermeer s 34 paintings on canvas 8. a composite image containing thread density maps of the painting being studied and its close count matches to the same scale and colorbar for weave match hunting 9. comments on observed cusping and weft snakes Observations: The average thread density of Officer and Laughing Girl is (H x V) is 14.38 x 14.39 th/cm. Officer and Laughing Girl has cusping of depth greater than 5 cm on all four sides. Officer and Laughing Girl has six close count matches, but no apparent weave matches, among Vermeer s other paintings on canvas. The horizontal thread angle map of Officer and Laughing Girl displays two weft snake indicators.
Johnson and Sethares, Weave Map Report, August 2017 3 Background Manual thread counting has been used for several decades. One canvas descriptor that has been routinely collected is the average thread count of the threads in each direction (vertical and horizontal) in a painting s canvas. This information has been used to discount the possibility of two canvases coming from the same original roll if their average thread counts (horizontal compared to horizontal and vertical compared to vertical or horizontal compared to vertical and vertical to horizontal) are too different, e.g. by more than 1 th/cm. In 2009, the first weave maps derived from automated thread counts based on a spectral analysis of the painting s x-radiograph were shown at the annual AIC meeting in Los Angeles. The stripes that arise in color-coded images of thread count in small evaluation squares covering the entire painting were immediately recognized as a fingerprint of a specific roll. The first weave match was also shown in this talk [1]. The utility of automated thread counting for canvases with a sufficiently regular weave was confirmed in [2]. Weave matches with art historical implications have been reported for paintings by van Gogh [3], Velázquez [4], and Vermeer [5] [6]. Spectral-based automated thread counting also provides angle maps that make cusping assessment [7] and weft snake hunting [8] easier. Descriptions of the revelations possible from these new visualizations of canvas weave density and thread angle are provided in [9]. Technical description appears in [10] of the algorithms used in composing and comparing weave maps. References [1] C. R. Johnson, Jr., E. Hendriks, P. Noble, and M. Franken, Advances in Computer-Assisted Canvas Examination: Thread Counting Algorithms, 37th Annual Meeting of American Institute for Conservation of Historic and Artistic Works, Los Angeles, CA, May 2009. [2] C. R. Johnson, Jr., D. H. Johnson, N. Hamashima, H. S. Yang, and E. Hendriks, On the Utility of Spectral-Maximum-Based Automated Thread Counting from X-Rays of Paintings on Canvas, Studies in Conservation, vol. 56, pp. 104-114, 2011.
Johnson and Sethares, Weave Map Report, August 2017 4 [3] L. van Tilborgh, T. Meedendorp, E. Hendriks, D. H. Johnson, C. R. Johnson, Jr., and R. G. Erdmann, Weave Matching and Dating of Van Gogh s Paintings: An Interdisciplinary Approach, The Burlington Magazine, vol. CLIV, pp. 112-122, February 2012. [4] Pablo Pérez D Ors, C. R. Johnson, Jr., and D. H. Johnson, Velázquez in Fraga: a New Hypothesis about the Portraits of El Primo and Philip IV, The Burlington Magazine, vol. CLIV, pp. 620-625, September 2012. [5] W. Liedtke, C. R. Johnson, Jr., and D. H. Johnson, Canvas Matches in Vermeer: A Case Study in the Computer Analysis of Fabric Supports, Metropolitan Museum Journal, vol. 47, pp. 99-106, 2012. [6] C. R. Johnson, Jr. and W. A. Sethares, Canvas Weave Match Supports Designation of Vermeer s Geographer and Astronomer as a Pendant Pair, Journal of Historians of Netherlandish Art, vol. 9, issue 1, Winter 2017. DOI: 10.5092/jhna.2017.9.1.17 [7] P. Noble, A. van Loon, C. R. Johnson, Jr., and D. H. Johnson, Technical Investigation of Rembrandt and/or Studio of Saul and David c. 1660 from the Collection of the Mauritshuis, ICOM-CC 2011 Lisbon Triennial Conference, Lisbon, Portugal, September 2011. [8] C. R. Johnson, Jr., D. H. Johnson, I. Verslype, R. Lugtigheid, and R. G. Erdmann, Detecting Weft Snakes, Art Matters, vol. 5, pp. 48-52, 2013. [9] D. H. Johnson, E. Hendriks, and C. R. Johnson, Jr., Interpreting Canvas Weave Matches, Art Matters, vol. 5, pp. 53-61, 2013. [10] D. H. Johnson, C. R. Johnson, Jr., and R. G. Erdmann, Weave Analysis of Paintings on Canvas from Radiographs, Signal Processing (Special Issue on Image Processing for Art Investigation), vol. 93, pp. 527-540, March 2013. Note: All of these references are available for download from http://people.ece.cornell.edu/johnson/selpubs.html
Johnson and Sethares, Weave Map Report, August 2017 5 Observations X-Radiograph: The x-radiograph of L06 in Figure 2 is very dark in large portions of the painting. These sizable monotone regions make manual thread counting and the assessment of cusping and weft snakes from the x-radiograph difficult. Average Thread Count: For L06 the average thread count (H x V) is 14.38 x 14.39 th/cm. These values are noted at the top of the images in the top row of Figure 3 along with the standard deviations of ±1.3 th/cm (H) and ±1.57 th/cm (V). The thread counts were computed in evaluation squares 0.5 cm on a side centered on a grid of points with 0.25 cm horizontal and vertical spacings. The histograms of the thread counts in each thread direction in the evaluation squares, as well as the histograms of the thread angles computed in the same evaluation squares, are plotted in Figure 4. Tight Count Matches: All of the weave matches discovered so far among the canvases in paintings by Vermeer have had both thread counts within 1 th/cm of each other. Using this metric for the designation of a tight count match, L06 has six: L07 (The Milkmaid, Rijksmuseum), L10 (Young Woman with a Wine Glass, Herzog Anton Ulrich Museum), L11 (The Little Street, Rijksmuseum), L17 (Woman Reading a Letter, Rijksmuseum), L22 (Girl with a Pearl Earring, Mauritshuis), and L23 (Study of a Young Woman, Metropolitan Museum of Art). Weave Matches: Figure 9 is designed to assist in assessing if any of the six tight count matches is a weave match to L06. In Figure 9 all images are to the same scale, which is necessary for visual evaluation of potentially matching stripe patterns. The first two images in the second row are the horizontal thread density map of L07 and the vertical thread density map of L07 - rotated 90 degrees so the stripes are horizontal - with the same colorbar as used for the horizontal thread count for L06 on the left in the top row of Figure 9. These are to be placed on either the right or the left of the left image in the top row and moved up and down looking for a match of the stripe patterns. The images from the second row should be rotated 180 degrees as well in seeking matches in the striped patterns. No alignment offering a match of the striped patterns is apparent. A similar visual check is made with the third and fourth images in the second row
Johnson and Sethares, Weave Map Report, August 2017 6 of Figure 9 against the right image in the top row. The last two images in the second row are the vertical thread density map of L07 and the horizontal thread density map of L07 - rotated 90 degrees so the stripes are vertical - with the same colorbar as used for the vertical thread count for L06 on the right in the top row of Figure 9. These are to be placed either above or below of the right image in the top row and moved right and left looking for a match of the vertical stripe patterns. Also, 180 degree rotations of the two rightmost images in the second row should also be considered for matching stripe patterns. No alignment offering a match of the striped patterns is apparent. Of these four images in the second row, only one (or none) can have a match with the corresponding images in the top row. This examination is repeated for the remaining rows containing the weave maps to be compared for all of the other tight count matches to L06. Again, no alignment offering a match of the striped patterns is apparent. Consequently, there appear to be no weave matches for L06 among Vermeer s paintings on canvas with a close count match to L06. Weft Snake Indicators: Two weft snake indicators are apparent in the vertical thread angle map of Figure 8. One is about one-third of the painting s width in from the left side. The other is slightly less than onethird of the paihnting s width in from the right side. As the x-radiograph in Figure 2 is quite dark, the best place to hunt for a wiggly bundle of threads, i.e. a weft snake, is in the vicinity of where the weft snake indicator strikes the bottom edge of the painting. Both weft snake indicators can be associated with modestly wiggling weft snakes. Thus, the vertical threads in L06 are the weft threads. Cusping: From the thread angle maps in Figures 7 and 8, cusping can be observed as greater than 5cm in depth on all four sides of L06.
Johnson and Sethares, Weave Map Report, August 2017 7 Acknowledgments The authors of this weave map report on one of Vermeer s paintings on canvas are grateful to the owners of Vermeer s paintings, all of whom gave us access to high resolution digitized x-radiographs of their Vermeers Walter Liedtke (Metropolitan Museum of Art) and Gregor Weber (Rijksmuseum) for their help in persuading the owners of paintings by Vermeer to grant us access to their x-radiographs Rob Erdmann (Rijksmuseum) for expertly assembling full-painting composite x-radiographs all of our research collaborators and thread-counting students over the past decade since the founding of TCAP: the Thread Count Automation Project (http://people.ece.cornell.edu/johnson/ tcap.html).
Johnson and Sethares, Weave Map Report, August 2017 8 Images Figure 1: Officer and Laughing Girl (L06) Note: All of the following images (Figures 2-9) are available on request as high resolution tiff or pdf files.
Johnson and Sethares, Weave Map Report, August 2017 9 Figure 2: X-Radiograph of L06
Johnson and Sethares, Weave Map Report, August 2017 10 horizontal thread density (14.38 +/- 1.3 threads/cm) vertical thread density (14.39 +/- 1.57 threads/cm) horizontal thread angles (+/-5.14505 degrees) vertical thread angles (+/-4.60454 degrees) Figure 3: Weave Maps of L06
Johnson and Sethares, Weave Map Report, August 2017 11 Figure 4: Histograms of Thread Count and Angle Computations for L06
Johnson and Sethares, Weave Map Report, August 2017 12 17 16 15 14 13 12 11 Figure 5: Horizontal Thread Density Map of L06
Johnson and Sethares, Weave Map Report, August 2017 13 17 16 15 14 13 12 11 Figure 6: Vertical Thread Density Map of L06
Johnson and Sethares, Weave Map Report, August 2017 14 20 10 0-10 Figure 7: Horizontal Thread Angle Map of L06
Johnson and Sethares, Weave Map Report, August 2017 15 110 100 90 80 70 Figure 8: Vertical Thread Angle Map of L06
Johnson and Sethares, Weave Map Report, August 2017 L06 H: 14.3817+/-1.29504 th/cm V: 14.3869+/-1.56593 th/cm L07 H: 15.1845+/-1.54202 th/cm V: 15.3616+/-1.63425 th/cm L10 H: 14.857+/-1.41386 th/cm V: 14.742+/-1.35362 th/cm L11 H: 14.908+/-1.48554 th/cm V: 13.866+/-1.36229 th/cm L17 H: 14.9136+/-1.41198 th/cm V: 15.2289+/-1.58213 th/cm L22 H: 14.658+/-1.46495 th/cm V: 14.4953+/-1.57839 th/cm L23 H: 14.9426+/-1.32076 th/cm V: 15.37+/-1.51531 th/cm Figure 9: Tight Count Matches of L06 16