Thinking about colour • 1

In feedback after assignment 4, my tutor commented:

You have clearly observed and recorded colour in the work and created your own colour palette. In relation to this I would like to have seen further development with research into theory and symbolism in the use of colour.

I therefore plan a series of three postings, between now and the end of the course, dealing with colour. As Itten(1974) has pointed out, there are many ways of looking at colour: a physicist will be interested in radiation and optics, a chemist in the nature of pigments and paints, a painter in the way that colours interact on the canvas etc.

This first posting, dealing loosely with the scientific background, will be mostly unreferenced because the starting point is high school physics lessons and other influences too deeply ingrained to unravel.

What colour is

Visible light is one manifestation of electromagnetic radiation. The full spectrum ranges from radio at one end to gamma radiation at the other, a total of 400 octaves of frequency (Asimov ‘Four hundred octaves’ a 1982 essay collected in Asimov 1984). Of this, slightly less than one octave (approximate wavelengths between 400 and 700 nanometers(frequency 430-750THz)) is visible to the human eye. The phenomenon that we call colour is the brain’s way of interpreting the difference between frequencies of visible light.

1210px-linear_visible_spectrum-svg

source: Wikipedia

These colours can be seen in natural phenomena such as rainbows, but it was only when Isaac Newton demonstrated splitting and recombining the colours from white light with a prism that the principle was understood. The spectrum above also shows the invisible radiation at either end of the visible range, infra-red and ultra-violet, which can also be recorded by cameras. The naming of the traditional seven colours has more to do with mysticism than science: indigo is really a dark blue and there are no discrete colours in a continuum.

The (in my opinion) questionable next step is to turn the linear spectrum into a ‘colour wheel’ by stitching the red and blue ends together through a range of colours known variously as purple, magenta or mauve. I suspect the reason why these colours are difficult to describe is that they are conceptually artificial.

The 1990 Schiffman diagram is the most ‘honest’ of these examples as it shows the pink-purple sector is separate from the ‘rainbow colours’. It also introduces the concept of saturation. However, whatever the scientific basis, the full colour wheel can be justified because it ‘works’ for colour mixing.

Primary and secondary colours

Although colours have almost-infinite variety, it is not necessary to have an enormous number of colour sources to reproduce them.

It is notionally possible to select a smaller number of ‘pure’ colours and mix the others from them. How many colours, and which, will depend on personal choice, the nature of the medium and the way in which the primaries are mixed. Usually, three primaries are used. Artists mixing paint, and schoolchildren using crayons, use red, yellow and blue as seen in the first diagram below.

The standard when mixing lights, and on colour TV screens, computer monitors etc. is to use red, green and blue, as illustrated in the middle diagram. This type of mixing is called additive because the lights are added to each other, the secondary colours (formed by mixing equal amounts of two primaries) are lighter and it is possible to produce white by mixing all three equally.

When printing, including computer inkjet and laser printers, the inks lie on the white paper and subtract some colours from the white base. Adding further ink reduces the colour still further and this type of mixing is called subtractive. The subtractive primaries are the same as the additive secondaries (cyan, magenta and yellow), producing red, blue and green when mixing in pairs and, notionally, black when they are all mixed together. In practice, a mixture of the three pigments is a rather muddy, dark colour rather than pure black, so printers will add a black ink to the set, giving the standard CMYK (Cyan, Magenta, Yellow, blacK) inkset of low-end printers. Because of technical issues in the way the inks are formulated and applied, the colour mixing of the basic four colours is not perfect, and high-end printers use additional colours to fill the perceived gaps. For instance, my Canon PixmaPro 9500 uses ten inks in nine colours: the basic CMYK set, lighter versions of magenta, cyan and black, plus red and green. There are two different blacks (matt black MBK and photo black PBK) but this is about ‘glossiness’ rather than colour.

Colour temperature

The colour of a scene depends on the colour of the light illuminating it. The eye and brain will accommodate this, to some extent and perceive the scene in its ‘true colours’. The process of ‘colour correction’ is an attempt to alter the true colour of the scene to accord with the way it is perceived.

The main reason for colour variation is the temperature of the light source. A physical concept called ‘black body radiation’ says that the amount of radiation emitted by a body increases with its temperature, and also that the average colour (peak of the frequency curve) tends toward the higher-frequency, short-wavelength blue end of the spectrum.

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source: Wikipedia

Thus, the sun with its surface temperature of about 6000K emits light that we perceive as white (that being what the eye has evolved to do) but an incandescent light bulb, with a coil temperature of 3000K emits mainly infra-red (heat) radiation plus some visible light at the red/yellow end of the spectrum. The situation is more complicated with fluorescent sources, which have a discontinuous spectrum and require correcting on the green-magenta axis as well as the blue-yellow axis.

One curiosity is that the bluer colours are considered ‘cooler’, while red and yellow light is considered ‘warmer’ and more comforting, in contradiction to their relative physical colour temperatures. Partly, this is due to common experience; fire is yellow, ice is bluish. However, I speculate that part of the cause relates to Rayleigh scattering, by which the red-yellow light from the sun reaches us directly, while blue light is scattered and turns the entire sky dome blue. This means that an outdoor scene effectively has mixed light sources. Objects directly lit by the sun have a yellow tint while objects in shadow are lit by light from the sky dome and acquire a blue tint.

The next posting of the set will look at the way colours are used together, whether harmonious, complementary or ‘clashing’.

The final posting will look at some of the symbolism of colours.

References

Asimov, I. (1984) X stands for unknown. New York, NY, United States: Bantam Doubleday Dell Publishing Group

Itten, J. (1974) The art of color: The subjective experience and objective rationale of color. 2nd edn. New York: Wiley, John & Sons

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Assignment 4 – rainy evening in Maidstone

These images come from an early-evening walk through Maidstone. There had been rain earlier in the day (and there was a shower while I was out on this exercise) so everything was wet and producing reflections.

All images were made with a Pentax K-1 and 24-70 f/2.8 standard zoom, apertures between f/4 and f/8, and mostly at the long end of the zoom range. Exposure was in aperture-priority mode with -1EV compensation. However, when processing the PEF raw files, I found that I was increasing the exposure by about 1 stop. White balance is set to ‘daylight’ (5500K) because that is what the eye/brain defines as white or neutral and it allows the true colour of the artificial light to be seen. Sensitivity is ISO12800.

I shot lot of images (318!) although, I would like to think, not indiscriminately. With the creativity criterion in mind, particularly experimentation, I was looking for as many ‘different’ ideas as possible in the hope of developing one into a series for assessment.

General views did not work for me. Maidstone is not particularly beautiful and most of its lighting is utilitarian, rather than for display. I had hoped for some floodlit night working in the road works, similar to some of Zachmann’s China Nights images, but no luck. There is a possibility of making some traffic-trail images if  I revisit with a tripod.

Here are some more specific ideas. The railway stations are well-lit but, I suspect the resulting images would be short on creativity. The road markings in the car park have some appeal (and I spent time here) and have scope for a series. The public-art illuminated pylon and the light fitting with cobwebs are strictly one-offs.

Shop windows are tempting, particularly unlit windows reflecting the illuminated signs of the shop opposite. However, most displays and lighting have been ‘designed’, so photographing them is really riding on somebody else’s creativity.

This is an idea that I am seriously considering: examining the effect of street lighting on foliage, particularly where the tree has been allowed to engulf the light fitting. Some care is needed to find the right tree and the right viewpoint. I also found that, in a well-lit area, the effect is lost.

Finally, the type of image that I set out to shoot, artificial light sources reflected and showing off the various paving textures in the town. I am influenced by Rut Blees Luxemburg’s Liebeslied series of intimate cityscape details. Her images are very long exposures on large-format film, while mine are typically 1/25s on a digital full-frame sensor, but we do share a preference for showing the true colour of the light. I am not sure that using a tripod and long exposure would make much difference (other than allowing me to use a lower sensitivity and reduce noise levels) except where puddles are deep enough to have ripples.

In shooting this last set of images, I particularly enjoyed the details on the ironwork (gullies and manhole covers etc.) which also act as ‘symmetry breakers’ in the paving patterns.

My final choice will be between street-lit foliage and ironwork in reflective pavings. This will require a second expedition on another rainy night, but this time more focussed.

References

Campany, D. (1999) A conversation between Rut Blees Luxemburg and David Campany 1999 [online] at: http://www.union-gallery.com/content.php?page_id=653 [accessed 18/8/16]

Magnum (2104) China Nights 2005 – Patrick Zachmann [online] at: https://pro.magnumphotos.com [search string omitted for clarity]

Assignment 4 – initial thoughts

We are told to revisit one of exercises 4.2, 4.3 or 4.4 and prepare it for formal assignment submission, with particular reference to meeting the Creativity criteria for assessment.

I have chosen to revisit exercise 4.3, discovering and expressing the beauty of ambient artificial light because I think that is the one most likely to inspire some imagination and invention (and possibly a glimmer of personal voice). Exercise 4.2 leads to some rather ‘samey’ images and is at the mercy of the weather as it develops on the chosen day. Exercise 4.4, studio lighting, is completely under the photographer’s control so there is little scope for an element of surprise leading me in an unexpected direction.

Looking back at my London images (all 160 of them) having completed exercise 4.5,  I realise that they fall short on creativity. All are records of what was in front of the camera from an eye-level pedestrian viewpoint. I will, therefore be making a new set of images.

The new images will be of Maidstone town centre at night. Being only 10 minutes walk from home, it allows me to go out on impulse or to keep an eye on the weather.

Maidstone presents its own challenges, however. I will have to ‘find’ beauty in some rather utilitarian lighting. There is little of the gaudy display lighting that Shintaro has photographed, but I may be able to use working light for a civil engineering project currently in progress around the bridges, emulating Zachmann.

My intention, on my first exploration, will be to combine Luxemburg‘s close-up views with Brassaï‘s reflections in wet pavements. I will be shooting hand-held, for flexibility, exploiting the high ISO sensitivity of the K-1, looking for details of reflections in surfaces and puddles. Once I have located some interesting subjects, I may return with a tripod for long exposures. It will be interesting to see whether I can emulate Luxemburg’s ‘kind of alchemy’.

Exercise 4.4 -lighting ex nihilo

For this exercise, I stole a basil plant from the kitchen window ledge. This gave me two contrasting textures, the organic form and slight sheen of the leaves, and the flat sides and glossy surface of the ceramic pot.

Equipment and general set-up is shown above. I created an infinity curve with a roll of mid-grey background paper on the dining room table. The camera is locked-down on a tripod, manually focused and set in ‘X’ mode at an aperture of f/16. Exposure adjustments were made by varying the light intensity. Although I shot in RAW format, I made no post-processing adjustments before exporting to JPEG.

This is my default starting point for lighting set-up, perhaps influenced by my architectural drawing background in which shadows, if added to an elevation drawing are conventionally shown as if the light source was at 45˚. It does a workmanlike job, the combination of sheen and shadow on the leaves giving a good indication of overall form and individual curves.

As I suspected, lighting with a single point source gives unacceptable (in the context of this subject) shadows on the left side and loses detail in the ‘internal’ leaves. Of the two alternative methods for lighting the shadows (fill light or reflector) I consider the fill light to have worked best in this case. Being close to the lens axis, it has been better able to penetrate to the interior of the plant.

With this set-up, the main light is behind the plant with the intention that the form of the leaves would be defined by sheen. It is inevitable that the front will be in shadow, so some fill lighting is essential. It is interesting to compare the main+fill and main+reflector images as the effect on the pot is very different, with different facets lit.

Again, my preference is for the final image in the sequence, with both lights and a reflector.

The starting point for this set-up is similar to the basic 45˚ lighting but with a large light source to give a softer light. Because the light wraps-around to some extent, there is better lighting to the interior of the plant, but we still have the heavy shadow and undefined leaves at the rear left.

The intention of the kicker is to define that part of the plant by a combination of rim light and sheen. It work tolerably well (third image) and it is arguable whether it is improved by the addition of a reflector. The reflector improves brightness at the left, but also flattens the lighting on the left side. On reflection, this image could be improved by the use of a smaller reflector or by placing it further from the subject.

Lighting from above gives a different set of shadows, and emulates the lighting that the plant is most likely to be seen in. It was interesting to watch the changing light, particularly on the pot, as I changed the angle of the reflector.

Overall, my preferred image from the exercise is 2D, rear diagonal lighting with front fill and reflector.

Exercise 4.4 – Lighting the lion (a mistake to learn from)

For this exercise I chose to light a soft toy lion. The reasons for the choice included the surface texture and the mane, which I hoped would pick up rim lighting. In practice, the furry surface texture killed the definition of the shadows and specular highlights and, thus, the definition of form.

On the basis that every mistake is an opportunity to learn, I will post the results anyway, but will repeat the exercise with a new subject.

This is intended as the ‘control’ exercise. The camera is, effectively, at the bottom-centre of a 1000mm x 2000mm soft box, giving flat an almost shadowless light on the subject. The outline shape and colour are clearly delineated but there is no sense of three-dimensional form.

It is said that the skill of studio lighting lies not in where one places the lights but where one places the shadows. This is explored in the other lighting set-ups.

I first attempted this set-up using the large soft box, but the light-source was too large and the lighting too flat. ‘Rembrandt lighting’ is intended to emulate the painter’s studio, which had large windows at high level. The main light is large, and high at at about 45˚ to one side. Because I was operating in a small room, there is a lot of stray bounce-light, which fills the shadows even without a reflector on the lit side. Having tried both, I prefer the version without reflector which has a greater lit:unlit contrast.

Of course, the shape of the subject’s head is non-human and does not show the characteristic triangular light on the far cheek.

This is a first attempt to emulate ‘Karsh lighting’, which fails because the shape of the subject’s head does not suit the technique. However, experimenting was instructive and it appears that the placing of the rim lights is critical.

I first placed them at 45˚ to the rear of the subject, which gave really good backlighting to the mane but put the face in deep shadow that could not be relieved by the reflector. This might have worked if a third light was available as fill-in to light the face from the front.

With the lights only slightly behind the subject, there is better wrap-around but a lot of spill onto the background. ‘Feathering’ the lights forward reduced the background spill and, usefully, put more light onto the reflector and, therefore, onto the face.

On reflection, I am pleased with the final result (largest image)

This is the same set-up as the Rembrandt lighting but with a much larger light source, therefore softer lighting. The image shown above is made without the reflector. With a reflector in place at the left, the contrast is lower and the lighting almost flat.

The large soft box is a light-source that extends from 45˚ in front of the subject to 45˚ behind, causing the light to ‘wrap around’ the right-hand side. The version without the reflector is reasonably successful.

 

The same set-up as above but with a bare-bulb light-source. The shadow cuts the subject in half and, unlike the set-ups with large, soft light sources, the version with a reflector is preferable  as it gives some detail to the left-hand side of the face.

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Finally, and just for fun, an exercise in sinister lighting from below. Lighting is a single flash with a snoot and honeycomb, and a red gel, directed at a mirror on the table in front of the subject and reflecting upward.

Exercise 4.3 – ambient artificial light

These images were taken during an evening walk through central London. They were taken between 7:20pm and 8:45 on an evening when sunset was at 7:03. Therefore, they show a transition through the ‘blue hour’ into full night-time.

All images were made with a Pentax K-1 and 24-70mm f/2.8 lens used in manual exposure mode. Most used ISO3200, apertures between f/4 and f/8 and handholdable shutter speeds.

I shot in RAW, so colour temperature decisions could be deferred until post-processing. I follow Rut Blees Luxemburg’s preference for embracing the real colour of the light source rather than attempting to correct it, so I have set a ‘daylight’ white balance (5500K) in all cases.

Post-processing was in Lightroom, where I adjusted overall contrast (and, occasionally, exposure) to fit my subjective memory of the scene. The typical adjustment is to open the shadows (moving the ‘shadows’ slider to the right) and tweak the ‘whites’ and ‘blacks’ sliders so that there is marginal clipping at both ends of the dynamic range. If this were a camera club competition, I would be tempted by local adjustments (grads and post-crop vignetting) but I have eschewed them for this exercise.

The main question with shooting night-time cityscapes is whether to use the artificial light sources as illumination (see Luxemburg or Brassaï) or as the subject (see Shintaro). I have attempted both approaches in this exercise.

As seen in the set above, in many well-illuminated spaces (street lit or internal), the emphasis is on quantity of light rather than its quality. Typically, there are multiple overhead light sources giving a soft, even, shadowless light. In Northumberland Avenue, the street lighting is bright enough that the illuminated theatre sign can be rendered without resorting to HDR.

In this set, the lighting is more directional. The floodlighting from the SNOG bus is intended to give a coloured ‘stage lighting’ effect while its internal lighting gives working light to the servers and, incidentally, illumination of the customers’ faces. With the couple reading the menu, there is overall street lighting but their faces are lit by the illuminated menu acting as a large softbox. In the bar image, there is no street lighting and the two figures are lit by very strongly coloured lights intended for dramatic illumination of the building.

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In this image, shot in Trafalgar Square, the rather dim general light comes from the reflected floodlighting on the National Gallery but the womens’ faces are lit by their torchlight reflected from the pages of their guidebook.

In these wider views, the scene and the sky are dark or black and it is the light sources, and their reflections, which are the subject. Water is an obvious reflector, but I also used glossy paintwork on buses, taxis and other vehicles, and a surprising amount is reflected from dry roads and pavements which are ‘polished’ by use and seen at the right angle.

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This is the classic ‘light-source-as-subject’ image, of Eros in Piccadilly Circus and the Coca-Cola ad behind him. I spot-metered the red of the illumination as a mid-tone and let the other tones fall as they will. My regret (and I will go back and re-shoot sometime) is that I set the shutter speed too fast (1/1250s) rather than closing the aperture or setting a lower sensitivity, which has caused a form of pixellation in the changing LED displays.

The final image is my favourite of the evening. The neon sign in the window is a picture element itself but also gives that glorious red internal illumination.

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Exercise 4.3 preliminary – transition time

My main response to exercise 4.3 is a set of night-time images, taken in central London on 20 September. The images in this posting are a subset taken over a 10 minute period around sunset, between 7:01pm and 7:10. Sunset was 7:03, not that one would notice, given the heavy overcast. What is noticeable is the rapid change of light levels and the changing relationship between the intensity of the artificial light and the lightness of the sky.

Images were made with a Pentax K-1 and 24-70mm f/2.8 lens, used in manual exposure mode. There was minor tweaking in Lightroom, to adjust overall contrast rather than exposure.

All images were shot in RAW mode, deferring decisions on colour temperature until post-production. All images were set to ‘daylight’ (5500K) colour balance to enable a proper assessment of colour changes.

The interesting point is that, with the exception of the very bright ‘stage lighting’ floodlights on the SNOG bus, the artificial lights are insignificant in relation to the overall daylight levels. The first of the images used in Exercise 4.3 was taken at 7:20pm, 17 minutes after sunset, by which time the scene had darkened noticeably and it is the artificial lighting that dominates.