Luminance adjustments

This is posted in response to Cee’s Compose Yourself Challenge Lesson #24: Black & White Post-Editing. As in Cee’s post, I have four original colour photographs, each also converted ‘as is’ to Black & White and then edited simply by shifting just one colour slider.


This mosaic picture graces one of the underpasses on the Corniche road in Abu Dhabi. The straight conversion doesn’t really do much more than drain the life from the image…

…but reducing the Luminescence of the Green channel to zero brings it back:




This – obviously – is a windsock, to be found at the airstrip just outside nearby Blond. Any interest the image has is largely in the strong diagonal composition rather than the colours, but nonetheless it provides a useful example for the purpose of this post.

There is, effectively only one channel to adjust – the Red one. Reducing the Luminance simply darkened the colour, increasing the contrast and showing up a lot of grain. However, increasing the Red Luminance gives a far more attractive image, I think:




The orange and yellow paint of this residential block in the old part of Dubai is far more striking than its ‘as is’ monochrome conversion.


Increasing Yellow Luminance is an improvement, though:




This purple wisteria hanging over a wall in Chédigny is an attractive shade of purple, providing a pleasing contrast with the stone background, which is lost in the straight conversion:

However, reducing the Luminance of the Purple channel gives the image much greater ‘presence’.



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