I'm looking to create my own images and want to make them in the exact size they'll be stored by the server to avoid them being resized by the plugin. I remember this post by Wulf back in the day. But I can't access the image since my account seems to have been deleted off the old site.

I also can't find where the images are stored in the server's save data. That's another thing I'd like to know so I can look at the images if the sizes change in the future or new sign types are added.

From that post you linked..

Landscape Picture Frame: 256x256
Tall Picture Frame: 128x512
Portrait Picture Frame: 128x256
XXL Picture Frame: 1024x512
XL Picture Frame: 512x512
Small Wooden Sign: 128x64
Wooden Sign: 256x128
Large Wooden Sign: 512x128
Huge Wooden Sign: 512x128
Large Banner Hanging: 64x256
Large Banner on Pole: 64x256
Double Sign Post: 256x256
One Sided Town Sign Post: 256x128
Two Sided Town Sign Post: 256x128
Two Sided Hanging Sign: 128x256
Two Sided Ornate Hanging Sign: 256x128
Spinning Wheel: 512x512 (only uses the upper left corner (256x256))

Thank you.