1 > Barrel or Pinch Distortion is removed:

2 > All sides are straightened to 90 degrees:

3 > Colors and brightess are equalized:

4 > Visual "Scars" are removed, allowing good visual tiling:
-gaps and lines are all averaged, and high-contrast anomalies are removed

5 > Any reflectivity is minimized:

6 > Internal perspective is minimized:

7 > Chromatic Aberration (purple fringing) is minimized:
-this is an extreme closup zoom-in

> Here are some extreme examples: