In your example, explaining what happened to the pixels is simply describing what the program did. My question would then be "how did the program decide to do these things?".
It didn't decide to do anything. The input photo is all the data collected about you. The output photo might be a single pixel describing your credit rating. And the filter is the entirety of the program. So our program might just be an excel macro creating a weighted sum of all the factors pertaining to your credit history.
This filter got built by data "scientists" who ran it over data for people where the results were known in advance, and tweaked those weights (1% of this pixel, 2% of that pixel) until the filter produced the results expected for the people whose histories were known. And then it was let loose on your data.