Negative space

I was interested to see what shots I could get from the car when we were driving along the Auckland motorways recently. It was quite late in the day, not long before dusk. At 100km/hr I was using 1600 ISO (no I was not driving). When I reviewed the photos later, I thought the writing on the wall was one of the semitic languages, and it took me a while to see the black paint was the negative space. What was I thinking? Now I just glance at it and I can see the large, fat, white letters. I have quite a collection of photos, some interesting, some mediocre, some blurry, and now have to decide whether I can use any of them. Maybe photocollage, or painting or collage. At least I'm starting to build up my photo resources again after losing almost everything I've taken since getting the digital SLR.