The aim of this exercise is to make practical use of channel adjustment to achieve a specific effect. I chose the option of a landscape in which you emphasise the depth (aerial perspective) by strengthening the visual effect of haze.
This is the channel mixer box after I converted the image to black and white and before I’ve started to adjust the levels.
This is the channel mixer after I’ve made the adjustments
Finally I made a default conversion within Photoshop CS6 using the desaturate option.
After reviewing the three images, the one that I prefer is the black and white adjusted tones as it has more depth in the colours of the grass and sky, and it highlights the different lines and paths more than the colour and the desaturated images.