Primary and secondary colours

This exercise will present a series of images representing each of the primary and secondary colours. Each example has been recorded at the default "correct" meter reading of the camera, but also with relative under and over exposure to explore how the colour rendering varies.

Blue Plus

An over-exposed image gives a lighter, brighter blue.

Blue

The straight rendering...

Blue Minus

While under-exposure seems to offer a more purple tonality?

Green Plus

The lighter example seems to emphasise the yellow content of the leaf.

Green

As metered...

Green Minus

While the darker image tends towards the blue tones - green being made by combining yellow and blue in subtractive colour mixing.

I am starting to think that varying the exposure of a colour has the effect of shuffling it around the circumference of the colour wheel a bit. In reference to the wheel above it seems that the darker images tend to move the tone clockwise around the wheel...

Yellow Plus

But the brighter yellow seen above would appear to lie between -

Yellow

the slightly orange tones here-

Yellow Minus

and the duller, almost greenish rendering here.

I wonder if part of the problem in understanding what is happening here is that the visible spectrum does not "chase its tail" into a circle to form a colour wheel, but in fact is just a small slice from the much wider, linear electromagnetic spectrum?

Image from  http://premediablog.widen.com/blog/the-color-space/call-me-mr-biv-v1

Orange Plus

A strong orange becomes more yellow in over-exposure.

Orange

The can is lit from the right, so each image has an exposure which varies from left to right - one may consider the changes as effectively rotating the field of view around the axis of the cylinder.

Orange Minus

Red Plus

An over exposed red looks rather pink.

Red

A red book...

Red Minus

The darker version looks a little purple, compared with the ones above.

Magenta Plus

These three are of interest in demonstrating the influence of the surface we are looking at. The purple text is printed on relatively rough newsprint, from The Guardian newspaper, which is why all three appear rather dull and poorly saturated. The texture of the paper scatters reflected light giving the effect seen. This is why photographs reproduce better on glossy, coated (more expensive) papers.

Magenta

The "straight" image, and the darker one below also show the effect of exposure variations on the background as well as the colour we are interested in. The "white" newsprint becomes positively grey as the exposure darkens.

Magenta Minus

Colour Relationships

The first images in the section demonstrate combinations of primary and secondary colours, seeking to present them in the proportions proposed by Von Goethe in his Theory of Colours (1810), thus making allowance for the relative brightness of each hue.

Red - Green

The one to one ratio is readily achieved here, a touch more of the red book being balanced by the title panel of the green one.

Orange - Blue

Orange is supposed to have a relative value of 8, compared with the 4 of blue. This example therefore has a larger area of blue background to balance the brighter oranges.

Yellow - Violet

Yellow is clearly the brighter here. Von Goethe ascribes it a value of 9, while violet is 3. The duck occupies about a quarter  of the image, which gives proportions of around 1 to 3. This does seem to give a pleasing balance to the different elements of this composition.

And now the really hard bit - choosing colour combinations that "appeal" to me!

Wheel of Allen Scythe

I find the colour in this image pleasing because of the relatively understated and muted tones. It is essentially composed with greens  contrasted with rust tones derived from the orange end of the spectrum. I terms of balance there is perhaps a preponderance of the warmer rusts, but I think this is compensated by the clearer and more vivid nature of the greens.

Facilities in Cammeringham

Ignore the box. The rest of this scene contains quite a lot of green, with some warmer tones to the stone and tile, with a delicate blue sky behind; the road surface is largely blueish. And then we have the box - an extremely positive statement in a red bright enough to dominate everything else. I think this could demonstrate that Goethe's theories of relative colour values apply best when the colours are of similar purity and saturation?

Pine buds

A similar, but less dramatic example. The colours here are again largely greens and browns, with snow providing areas of neutrality. An accent is provided by the surprisingly bright orange buds. The large bud in the centre immediately catches the eye, but then we see others dotted around the rest of the image.

Sunrise, 7:53 AM, 17th January

The colour in this example has not been enhanced in Photoshop. It was one of those truly vivid, if fleeting moments when the sky was afire... However, the camera  (photographer) is selective in what is revealed - the image below was taken with an 18mm focal length, the one above at 55mm. The broader picture is a little less Turneresque...

Sunrise, 7:54 AM, 17th January