A year ago I saw a photograph in a swimsuit special of the Dutch "de Bijenkorf Magazine" with a model holding a big card board behind her. It stood out because of the very bright colors and the composition.
I keep interesting reference material apart, so when I was thinking of doing a new pixel project I browsed the big pile of magazines and found her again!
I've changed several parts of the model, including the bikini, chose a totally different color palette but kept the card board set-up and created a brand new beach background.
Reference: Solar Initiative swimsuit model (unfortunally I could not find the digital version online).