Don't let your eyes play tricks on you. The original photo is black and white. The original photo is not sepia-toned and is affixed to a postcard. Since it's not sepia-toned the photo is almost blank to the naked eye after nearly 110 years of aging. The brown cast to the image is an effect of scanning it. The actual photo appears slighty off-white to the eye.
Just toying with The GIMP 1.3.21. Here's a screenshot taken while editing this photo.
| Raw Scanned Image | After Retouch |
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Both images are 1200dpi but the examples here have been downsampled to reduce file size.