Word or phrase for the surface appearance of an artwork

Solution 1:

In photo metadata we make a distinction between the Photo Description, and the Photo Caption. So Description would be something like "red voyageur canoe proceeding from upper left to lower right through rapids with chaotic currents. Far shore is red veined grey granite, with dense spruce. Where the caption may be, "Shooting Otter Rapids on the Churchill, June 2008" Caption isn't the same as interpretation.

Similarly I may describe

One way to think about this: How would you describe this image to a computer so that you could find it later? Or how would you describe it to someone who was blind?

E.g.

The site I snitched this from describes it as:

The Fighting Temeraire Tugged to her Last Berth to be Broken up (1838)

"Turner paints the veteran warship, hero of the battle of Trafalgar, as a pale and ghostly mass looming against a rich, panoramic sunset. It has a sense of latent power still not quite eclipsed by the raw mechanical energy of the flaming and smoking steam tug. Here we see Turner's interest in the new as well respect for what is past. This may be an elegy to what is gone, but is also an affirmation of the continuing energy, power and modernity of Victorian England."

(https://www.gq-magazine.co.uk/article/turner-paintings-top-ten-timothy-spall)

But describing it for computer or the blind:

Picture lower left: An early coal fired black tug is pulling a pale large three masted sailboat. The sea is nearly flat. Picture lower right: The sun is a dark orange and grey patch near the horizon nearly obscured behind smoke and cloud. Extreme lower right is a black object in the foreground. Upper half of the image is a patchwork sky of smoke and high overcast.

Style is impressionistic, with soft contrast and little fine detail.

Depending on your class, you may want more use of style descriptors, brushwork, glazes, underpainting.