I was attracted to this photo as there is a medieval princess look to this young woman’s hat. I’m very fond of portrait paintings from that era. The cone shaped hennin of the period, says royalty above all else and the demure expression on her very attractive face, gives her a regal bearing.
Closer inspection of the image suggests she is wearing a marching girl uniform of some sort, rather than a carnival or party costume. The insignia on the hat certainly suggests she is a member of an organisation or team of some sort.
This is an undated photobooth photo from France. It dates to around the 1940s. Perhaps, if you are more familiar with French culture than I, you might recognise this outfit? Let me know in the comments, if you do.