Limitation of postcards/ internet images
The limitations of postcards and internet images are unavoidable and are based on the size of the image. Obviously any reduction in size will lose detail. Colour is another thing which can be greatly affected in reproductions.
An example of this is Durer’s St Eustace. I was initially working on an image I found using a google search. I was able to annotate the entire image but I was frustrated when I tried to see the detail. I was not able to zoom in sufficiently to do this so I had another search. I chose the image by checking the sizes this time and I was very lucky to find a very large file which when I opened was a completedly different picture to the one I had been working on. The detail was incredible and the tonal variation had not been present at all.
I realise however that even this image may have been doctored to show the darker tones darker etc. For this reason I thinks its important to look at a range of images and choose one that is not only larger but is representative in colour and tone of the the majority of the images shown. Ideally of course you would work from an image you have seen in real life but even then, details are forgotten by the time you come home and start writing about it. Its therefore a good idea to make notes on these aspects when seeing the images in situ.
Can an Artistic or architectural style express particular values?
Yes, they can. The classical style was clean, linear and straightforward showing their ethos of simplicity and clarity. Gothic however was one of opulence and detail a reflection of the Christian values of the time. Height in architecture lifted the eye to heaven and visual art of the middle ages served to educate and remind the viewer of the gospels.
Artists expressed individuality
Aside from artists such as Durer using specific techniques such as engraving, each has had their own style. There seems to be an evolution of art when looked at it over time. You can see each artist is trying to develop their techniques and themes to make them different from what has come before. Does this individuality make a great artist?
Some artists are obvious at first glance, others are less so. Individuality only began in the early renaissance, before that artists were not identified. It possible to see individuality in colours used (perhaps due to more mundane access or media limitations than choice) the way subjects are tackled and their actual visual descriptions. Humanist elements and the use of the golden section identify Piero della Francesca. Linear perspective used by such artists as Bellini were another obvious identifier.