Aim: The aim of this exercise is to better understand the characteristics of modern digital black and white. That is the impact of adjusting 'colours' to emphasise part of the monochrome image.
Process: By raising or lowering the colour level in the black and white mixer panel, it is possible to emphasise and de-emphasise parts of the monochrome image. This is akin to putting a coloured filter on the front of the lens of a film camera loaded with monochrome film. Of course, having the full colour spectrum means that we can be much more subtle than just putting one filter on the front of the lens, so this is a powerful method of processing the monochrome image.
In this exercise we are instructed to be quite dramatic in our work, this is to show the power of adjusting the various channels, but in reality I imagine this would be used with more subtlety and perhaps even discreetly over parts of the image (perhaps using layers and masks in Photoshop) to selectively emphasise parts of the image.
Two images were chosen, one with contrasting red and green, and one with yellow and blue. I have chosen a couple of images taken on my regular walks around the local area. I have used Lightroom for this exercise, and simply used the button and dragged on the image to raise or lower certain colours. I find this to be a very intuitive and easy way of seeing exactly what is happening and let the software determine which colours need to be adjusted.
Image 1: Colour
Image 1: 'default' Monochrome
Image 1: Raising the red channel makes the flowers appear almost white, and the car very pale
Image 1: Raising the vegetation (mostly in the yellow channel for this image) and lowering the red channel makes the flowers appear dramatically dark and the vegetation quite pale
Image 2: Colour
Image 2: 'default' Monochrome
Image 2: Raising the yellow channel and lowering the blue channel makes the digger quite dark and the sky washed out and pale
Image 2: Lowering the yellow channel and raising the blue channel makes the digger bright and pale and the sky dramatically dark, with the few clouds in the sky standing out.
Conclusion: This fairly simple exercise demonstrates the powerful use of adjusting the colour levels for a black and white image. The possibilities seem endless for tweaking each image! I have chosen images that are very bold in their colouring, so the results are very dramatic (which I think was the point of this exercise). However I can imaging that in more subtly coloured images the results can be quite powerful also. This is an essential step in creating a 'good' black and white image, and one that will be added to my monochrome workflow.