Take or choose an image, which contains at least two strong contrasting colours (for instance, blue and green, or yellow and blue, or green and red). Using the channel sliders or controls available in your software (such as the Black & White option in Photoshop), create two opposite version of the image in black-and-white. In one, lighten the grayscale tone of one of the colours and darken the tone of the contrasting colour as much as possible. In the second version, perform the revers.
One of the tings you will find in this operation is that the channel sliders often affect areas of the image that you had not expected. Apart from anything else, an exercise such as this is very helpful in refining your sense of hue.
You should aim to produce two black-and-white versions with a strong difference in their tonal distribution. Write down what affect these different adjustments have on the creative quality of the image.
My colour combination for this exercise is Red and Green, with the red found in a lantern, surrounded by the green foliage of a tree. The original coloured photo is found below.
To begin with, after doing a little house keeping to the image (dust and hair spot removal) I made a standard black and white conversion using Photoshop’s black and white application.
This image is actually quiet flat in appearance and it is difficult distinguishing between the red and green tones. This is a little surprising as the original coloured version is so bright and vibrant; I am now interested to see where the next set of procedures will take me.
Next, in the black and white application, I moved the red slider to the right; just enough so that the highlights were on the verge of clipping, but stayed on the scale.
As expected, the red of the lantern is completely washed out, and now appears white. I expected more movement in the greens of the image, but they only appear slightly darker than in the original black-and-white version. I think the reason that the leaves in front of the lantern look a little darker is because of the starkness of the lantern.
This time I moved the green slider to the right, but this time I took it to the absolute maximum. Again, as expected, there has been a change in the tones of the green, but I am a little surprised that this change is not as evident as we saw when moving the red slider. This may be because the foliage is new, so is not a dark green but lighter in colour, although the leaves in front of the lantern do show a marked difference in tone.
Looking back at the image I chose for this exercise, the green colours of the foliage may not have been strong enough to manage the changes required by this exercise. That said, there was still movement of the colours into tones, which proves that the applications for these changes do work. It also proves that only drastic changes to tone will be applied to strong, bold colours; while subtle tonal change will only occur when applied to subtle, more gentle colours.