Gymnocalycium freidrichii flower

I've looked at the flowers on this cactus a number of times intending to photograph them, and when I have, the results have been unsatisfying. While the flower is mostly a pretty pink colour, the darker stripes are an unattractive, non-descript brown.

So today I've tried something different, not sure whether it works or not. As usual, I photographed this flower in our conservatory, against a black shirt that was hanging to dry. It has been so unseasonably wet and windy that yesterday's washing didn't get outdoors as usual.