Documenting Paintings with Gigapixel Photography

Abstract

Digital photographic capture of pictorial artworks with gigapixel resolution (around 1000 megapixels or greater) is a novel technique that is beginning to be used by some important international museums as a means of documentation, analysis, and dissemination of their masterpieces. This line of research is extremely interesting, not only for art curators and scholars but also for the general public. The results can be disseminated through online virtual museum displays, offering a detailed interactive visualization. These virtual visualizations allow the viewer to delve into the artwork in such a way that it is possible to zoom in and observe those details, which would be negligible to the naked eye in a real visit. Therefore, this kind of virtual visualization using gigapixel images has become an essential tool to enhance cultural heritage and to make it accessible to everyone. Since today's professional digital cameras provide images of around 40 megapixels, obtaining gigapixel images requires some special capture and editing techniques. This article describes a series of photographic methodologies and equipment, developed by the team of researchers, that have been put into practice to achieve a very high level of detail and chromatic fidelity, in the documentation and dissemination of pictorial artworks. The result of this research work consisted in the gigapixel documentation of several masterpieces of the Museo de Bellas Artes of Valencia, one of the main art galleries in Spain. The results will be disseminated through the Internet, as will be shown with some examples.

Keywords: art documentation; gigapixel photography; image registration; stitching; ultra-high resolution; virtual musealization.

Figure 1

Hans Holbein the Younger, 1533, The Ambasssadors. Picture and detail obtained from Google Arts and Culture [2].

Figure 2

Manual and motorized panoramic heads.

Figure 3

Obliquity between the shots and the canvas when using a panoramic head.

Figure 4

Loss of sharpness in an oblique shot due to narrow depth of field of long focal lenses.

Figure 5

Parallel camera translation to take all the pictures frontally to the canvas.

Figure 6

Single-viewpoint capture technique. The camera is rotated around its no-parallax point.

Figure 7

Parallel-multi-viewpoint capture technique. The camera moves parallel to the canvas.

Figure 8

Tilted-multi-viewpoint capture technique. The camera is moved mostly parallel to the canvas and can be tilted if needed. Normally, only the upper or lower rows would be tilted.

Figure 9

Lighting scheme to illuminate the artwork uniformly. In order to avoid specular reflections on the canvas, the light sources must be placed outside of the volume defined by the family of angles.

Figure 10

Lighting mount to attach the lighting system to the tripod.

Figure 11

Reference picture with the X-Rite ColorChecker chart that will help to set the proper white balance and to create a specific colour profile for the lighting conditions.

Figure 12

Single-viewpoint capture technique. Viewpoint position in the capture of the Santa Cena by Juan de Juanes (1534). Museo de Bellas Artes de Valencia (Spain).

Figure 13

(a) Set of 90 pictures taken during the gigapixel capture. (b) Stitched gigapixel Image.

Figure 14

Fragment of the resulting gigapixel image.

Figure 15

Remote control of the camera with the laptop via Wi-Fi.

Figure 16

(a) Set of 20 pictures taken during the gigapixel capture. (b) Stitched Gigapixel Image.

Figure 17

Fragment of the resulting gigapixel image.

Figure 18

(a) Set of 90 pictures taken during the gigapixel capture. (b) Stitched gigapixel image.

Figure 19

Fragment of the resulting gigapixel image.

Figure 20

For an interactive gigapixel visualization of the documented artworks use the QR codes or follow the links below. (a) https://gpix.webs.upv.es/gpix/305.html (accessed on 19 August 2021); (b) https://gpix.webs.upv.es/gpix/279.html (accessed on 19 August 2021); (c) https://gpix.webs.upv.es/gpix/2197.html (accessed on 19 August 2021).