I'm new to image processing and am learning about the Fourier transform. I've read that FT decomposes a function to its constituent frequencies. However, I'm not sure how to tell which is a low frequency or high frequency region in an FT image and why the transforms are shaped in the way they are.
For instance, in the image above why is the FT of the line oriented in the opposite direction and why is there a bright dot at the center of the random noise image? What are the ways the FT can be helpful here? Also, is there a trick or a general method of analysis that would work for a better understanding of FTs across a variety of images?