Graham Davies, Online Curator, Amgeddfa Cymru – National Museum Wales

When a member of the Art department approached me to ask if I could feature two views of the same painting online – one version covered in dirt and yellowed varnish (as the painting was when it came into the Museum), and the other version showing hidden detail and crisp colours (after being cleaned by Museum conservators) – I realised it would make a perfect interactive if you could use your mouse to virtually 'clean' the dirty canvas to reveal the clean version underneath.

Guardi's view of the Grand Canal, Venice

The painting in question is Francsesco Guardi's View of the Palazzo Loredan dell'Ambasciatore on the Grand Canal, Venice, painted around 1775-85.

Acquired by Amgueddfa Cymru in 2011, this painting is an important acquisition as Guardi's Venetian views are regarded as highly significant in the history of landscape painting.

You clean the painting

To make the most out of this dramatic before-and-after view, I needed to work out a way of 'virtually' cleaning the painting online by dragging a mouse over the dirty image to reveal the original details and colours previously hidden underneath the dirt and old varnish.

Reinvent the wheel?

I wanted something that allowed the mouse to act as an eraser, allowing one image to be rubbed out to reveal a secondary image underneath. A hunt around the internet brought up the required functionality already created by by Jonathan Nicol (www.f6design.com/journal).

The next step was to acquire high-resolution copies of both dirty (before) and cleaned (after) digital images of the artwork from the Photography department.

Precisely aligning two slightly differently angled photographs of the same picture

When I opened these digital images in Photoshop it became apparent that variations in the perspective, and distance of the photographic captures, resulted in two images that did not precisely match up once overlaid on top of one another.

After an hour of miniscule adjustments using the image warp feature on Photoshop, using the images as separate layers within Photoshop (one set at 50% opacity), I eventually achieved a precise overlaid match.

I abandoned trying to do this at 100% view as the image was so large and the time lag in processing too great to view the results (even for my G5 at 2.44Gz and 8GB RAM). I had to settle for a 25% view that filled my Apple 32" screen)

Once I had a satisfactory matched up and aligned the 'dirty' layer on top of the 'clean' layer, I could create the two corresponding TIFF images to incorporate into the Flash file as a basis for the interactive.

After a bit of tweaking, fiddling, and constant testing, I managed to create a simple interactive, allowing you to use your mouse to erase the dirt and grime, revealing the clean painting underneath.

Exploring the detail

I then decided to repeat this process to create several versions, all using crops of the high-resolution images to show close up details of the painting.

Areas of particular interest I chose to separate out were people rowing a gondola, the architectural detail of the buildings, and the detail of the sky and clouds where much original detail had been almost totally obscured by years of grime, dirt and previous 'touch-ups' to the painting. The clean version revealed original intricate details and brushwork.

Future applications for Museum archives and collections

I am hoping this functionality can be utilised for other online images of the collections in the future. Ideas I have at the moment are to reveal hidden under-drawings only visible under x-ray light — as in the example of Richard Wilson's Dolbadarn Castle (NMW A 72), which has been painted over a portrait of a woman, and Landscape with Banditti around a Tent (NMW A 69) which he painted over a Venetian-style reclining nude.

Additional ideas include viewing a landscape or post-industrial townscape that can be erased to reveal a historical image underneath...

Fe ymunodd y Cymdeithas Rhyfel Cartref Lloegr â ni y penwythnos diwethaf, i archwilio hanes Brwydr Sain Ffagan, ble yr ymladdod milwyr Cromwell a'r Brenin ym 1648. Fe ddaethon nhw â llond y lle o arfau, yn ôl y disgwyl - yn ogystal â nifer helaeth o sgiliau a gwrthrychau i'w harddangos. Byddai rhestr yn rhy ddiflas, felly dyma luniau o rai ohonyn nhw wrth eu gwaith! Diolch i Alcwyn Evans am dynnu'r lluniau.

Paratoi ar gyfer diwrnod o nyddu wrth ffermdy Cilewent

Gosod gwersyll y Seneddwyr ger ffermdy Abernodwydd

Taniwch!

Teulu o ail-grewyr. Roedd aelodau iau y grŵp yn hwyl i weithio hefo nhw!

Dynion a merched âd'u gwaywffyn, yn aros i fynd ar flaen y gâd

Uchelwr yng Nghastell Sain Ffagan, mewn gwisg o'r 1640au

Just a few more beauties!

This is a wonderful drawing by Charley of a Jester which ties in with our Tudor art theme.

Don't forget that art activities are running all through August, and if you haven't been before, now is the time to visit as it's generally a little quieter in the galleries when the weather is good!

At this juncture in the investigation of this block-lift, I am making every effort to outline the relationships (if any) between artefacts. As can be see in the first photograph, plenty of small pieces of iron plate, often with no telling association with larger plates, emerge as soil is scraped away. Aside from photographing their position for future reference, and examining them for signs of the remains of fittings, impressions of textile or leather, there is not much that can be done with these anonymous fragments. Moreover, these fragments often overlie more interesting and coherent features, and so I am generally removing these: I will most likely x-ray these in large batches at a later date. As you can tell by the annotations, I’ve begun to get a good idea of the fragile nature of the fragmentary, corroded copper and iron artefacts mixed in the burial deposit, and have begun to grasp how difficult lifting the larger pieces of lorica will be.

So far I have had limited success at recovering any ‘true edges’ of the iron armour, as most of the vulnerable thin plate has been broken. Finding edges greatly improves our chances of identifying plates, and where two edges have been found, dimensions such as the width of the plate can give us an idea of which part of the lorica cuirass the plate comes from. It also helps us to make educated comparisons with examples of Roman armour found from other sites. For instance, the iron plate recovered in the second photograph has a width of 6.5 cm across, dimensions similar to those recorded for the armour fragments found amongst the Corbridge Hoard, and from the Austrian site, Carnuntum. It also has the very corroded remains of two copper alloy rivets, which improves our understanding of how the cuirass was constructed and held together.

As I work I am keeping the surface of the soil block wet, by spraying it with deionised water. This prevents the soil from drying out too much, separating, and breaking the iron remains as it falls into chunks. As most of the iron is in such a poor condition, consolidation with a removable acrylic adhesive, such as Paraloid B72 (ethyl methacrylate copolymer) is a must (which is why in some photographs the iron surface appears to have a dark sheen to it).  

Whilst excavating an area of the block to the left of the photograph, I came across an exciting, (and sadly, very degraded) find: copper alloy wrapped around a thin iron plate. It can be seen in-situ in the photograph to the right, and after excavation in the photograph below. Sadly, as not much of the object has been recovered, a firm identification of this piece hasn’t been reached yet, though further excavation might yield more clues.

Readers may have noticed that I have begun to clean the outside of what is most likely a girth hoop. The exposed iron plate is 1mm in thickness, and the hoop is broken in several places, that I can see from the surface. When focusing on this feature, I will have to be careful to remove enough soil and other burial debris to reveal the curved plate’s shape, whilst maintaining the earthy support until I am ready to remove the that section of armour from the soil block. The next blog entry will focus on describing the results of excavations in this area, which includes a copper-alloy tie loop, still associated with the iron plate.