I’ve implemented a search function for the gallery. It can be found in the right sidebar of every album (Example: http://www.ww2incolor.com/other/) It’s not the prettiest, but it works fine.
I just noticed, could also be helpful to sort out reposts by using tags.
Cool improvement, thanks! 
This is really helpful considering how vast the gallery is. Thank you!!
It’s a really neat addition but one thing caught my eye, it lists the uploader as “Owner”, might be worth considering changing that due to copyright ownership.