Decisions, decisions.......

Right, I have decided on my final 8 pairs.

I shall drop "rough / smooth", as I don't think that the "smooth" fully conveys the idea of smoothness.  It is a kitchen pot, which is totally smooth to touch, but has a textured pattern on it which could give the impression of being rough instead.  I didn't see it at first, as I am used to the feel of the pot.  I do like the tree bark for "rough" though.
I am using the road photo for "straight" as several people have told me that it is effective in conveying the idea of straightness - Roman roads and all that.  I shall use the photo of the bananas for "curved", as I am much more pleased with this as an image than the road sign.  The idea of the road sign is, in my opinion, ok, but the actual photo isn't how I would have wanted it to be.  The background is too cluttered, and if I crop it down, it simply looks like a cut-out sign.  I couldn't get a road sign photo with a bend in the road behind it without compromising my safety on the roads around here.

So I have to contact my tutor and find out how to submit the assignment before I change my mind again !