X-ray photography analysis report.
An x-ray examination of an older oil painting was carried out on the order of the owners. The images are delivered to the customer in dicom format together with a simpler program that can read and manage these files. Also included are the original images in tif format and a set of filtered images, which can be combined in image processing software.
The painting depicts the Roman emperor Domitian (Domitianus). According to information from the client, the picture of Domitian was the last in a series of 12 portraits of Roman emperors. The first eleven portraits are said to have been painted by Titian in the 1530s, while it is unclear who painted the twelfth portrait. The series is said to have been sold later from England to the Spanish royal house and burned during the 18th century, but, according to the client, there is uncertainty about this.
The painting of Dominitian was sold in the 1920s by an English auction house as a painting by Titian. The painting is lined and retouched, unclear when and by whom. A 14C dating has been done and a research engineer at the laboratory writes: ”Unfortunately, the dating ends up in a non-linear area. The probability is higher that the canvas is from the late 15th century than the late 16th century, more than that we probably cannot say”.
A faint signature ”L da Vinci, Pinxt (or Pnixt)” can be seen under the man’s right elbow (fig 6). Depending on the light source, this is more or less visible. The area where the signature is found appears to be retouched, but should of course be examined by an expert/painting conservator and with the help of analytical light.
Purpose, method and questions.
The X-ray analysis is carried out partly to see if there is another painting on the canvas or if you can see if the artist (or someone else later) made adjustments to the motif, partly to see if you can see the signature with X-ray lighting.
Merging the images into a complete image in an image processing program is performed by the client.
X-ray analysis was performed with digital industrial X-ray (CR). Exposure facts are presented in table 1. Twelve image plates cover the entire image surface with some overlap and have been numbered 1-12, see figure 1. The dividing lines between the image plates are inserted approximately where the x-ray plates meet. The reason why the squares look different in size is probably because the photo of the painting was not taken completely straight on from the front (or from above). Another x-ray was taken of the area where the signature is.
Radiation source; Sitex CPseries, type CP160D. Scanner: Carestream Industrex HPX-1. Imaging plate:
Carestream Industrex Flex XL Blue Digital Imaging Plate 5537.
Results and Observations
The motif, weave structure, blind frame, damage and brush strokes are clearly visible in the images, but no traces of an underlying painting could be seen on initial inspection, however, there are details in the painting that cannot be seen on the x-rays, indicating that it has been ”improved” on one or more occasions (fig. 3-5). The laurel wreath has more leaves in the painting than can be seen in the x-ray. The shape of the armor edge appears to be more pointed on the painting than on the x-ray image and on x-ray image 4 a faint straight shadow of something that does not appear to be on the painting is visible. The comparison has been made of the X-ray images and a photo of the painting so there may be a possible source of error here. The images (in dicom format) should of course be studied more carefully by an expert.
Figure 2 shows the x-ray images (tif format) in the correct position, but not joined. Figures 6 and 7 show the area with the signature (customer’s photo and x-ray). The signature was not made clear by x-ray.