Line depth ratio D_{1 - D   NLTE}/D_{3 - D   NLTE} (left panels) and analogous ratio of equivalent width (right panels) as a function of the temperature difference to the local environment for all (x,y) positions of the hydrodynamic data cube. The point density is indicated by the colored shading in a logarithmic scale (yellow: 2, orange: 5, dark orange: 10, red: 20, etc. up to the innermost area in black with 1000+). The unit area was defined by subdividing the temperature axis into sections of 10 K and that of the EW ratio into sections 0.01. Regression lines are over-plotted and the corresponding correlation coefficients are given in the lower right corner of each frame.