What does 'energy' in image processing mean? I have been going through this paper: Seam Carving for Content-Aware Image Resizing which talks about resizing images by seam carving depending on the image energy or the energy function.

Some related quotes from the paper are:


  A seam is a connected path of low energy pixels in an image


and


  A seam is an optimal 8-connected path of pixels on a single image from
  top to bottom, or left to right, where optimality is defined by an
  image energy function


So, what does the 'energy' in an image mean, in this particular context?



PS: I have gone through this question, but the answers were very broad and vague because of this reason.
I quote from here which our friend has provided.


  Energy in this context is not, strictly speaking, the same as the conventional notion of energy in physics and the other sciences. The two concepts are, however, closely related, and it is possible to convert from one to the other:





  where Z represents the magnitude, in appropriate units of measure, of the load driven by the signal.


Also for figuring out the interpretation of energy in this context you can see here.


After a while, I found a bit better explanation for energy as you can read the answers from here. 


  Energy is used to describe a measure of "information" when formulating an operation under a probability framework such as MAP (maximum a priori) estimation in conjunction with Markov Random Fields. Sometimes the energy can be a negative measure to be minimised and sometimes it is a positive measure to be maximized.


or you can read:


  Energy is a fairly loose term used to describe any user defined function (in the image domain).