red hair?

I believe that light red hair photographed as if it were blonde in black and white films. Ginger's hair, in the 1930s, was a variation of reddish blonde or strawberry blonde. If you look closely at the earlier musical films, her hair seems to be slightly darker. Then, in the early 40s, she dyed her hair dark brown and reddish brown. Later, in the 50s and beyond, her hair was more of a light blonde.

Then, which was the real color of Ginger's hair? I always thought that she was a natural blonde, not a red-haired woman. Seems I was wrong.
Therefore her artistic name "Ginger" is because the color of her hair, or what?

To make it more confusing, in one of the original movie posters for Swing Time, she appears both as a blonde and as red-haired.

Take a glance:

http://images.heritagecoin.com/images/hnai/300/601/601001048o.jpg

http://seeadog.seminar.googlepages.com/swingtime.jpg/swingtime-full;init:.jpg

Here is a rare color photo from the production of Follow the Fleet, made about 8 months before Swing Time:
http://tinypic.com/m/4kij40/4

My mom always fights with me about her being a redhead, but I guess the term "strawberry blonde" didn't exist back then.