Saturday 20 August 2016

Research Point: Optical Effects

Optical effects have been exploited by many artists to create movement and depict the effects of light . The impressionists and neo-impressionists, in particular the pointillists: Seurat and Signac, made full use of the new understanding of the nature of human perception. Find out what you can about these artists' aims and study their pictures to see how they achieved such effects as optical mixing. Look also at the work of Bridget Riley and the op artists.

Optical mixing is a phenomenon in which a field of colour composed of small coloured shapes are fused in the mind of the viewer to give rise to the impression of a a whole field of colour or colour graduation. (1) How well the colours mix in the mind of the beholder is dependent on the how large the individual shapes are and their distance from the eye. 
Modern colour printing is an example of this phenomenon - for example inkjet printers produce images in a vast range of colours using tiny dots of 3 colours of ink (cyan, magenta and yellow) with black. (1)

In painting, collage and mosaics and other media, the individual shapes can be quite large allowing the phenomenon of 'dual visual awareness' to occur. Larger individual units of colour allow the viewer to alternate between to readings - from the physical presence of the spot of colour to their coalescence to form a picture or pattern. (1) 

This phenomenon has been exploited as far back as Roman times in mosaics:


Image Source:
http://www.mariamilani.com/ancient_rome/rome_art_mosaic.htm
It is still utilised by artists today. Chuck Close's monumental portraits appear almost photorealistic from a distance but they are composed of complex shapes: Small boxes containing squiggles of various tones and hues. The brain is able to arrange this complicated arrangement into a coherent whole(1)  Click Here to see a Self Portrait of Chuck Close on the Pace Gallery Website. 

Caroline McCarthy has employed a technique using small dots punched out of plastic bin bags in the colours used in colour printing to create a still life. The technique replicates the process of colour printing but on a larger scale.(2) Click Here to see image of 'Floral Still Life' 2007 by C McCarthy on 'Parkers Box' Website

The impressionists were undoubtedly not the first to exploit optical effects such as simultaneous and successive contrast. Delacroix said (Quoted by Charles Blanc in 1864) that the great colourists had always perceived the essential relativity of colour: they had never sought to establish 'le ton local', but had always worked through the manipulation of optical contrasts. (3) However this manipulation became more obvious with the impressionists and neo -impressionists.

The impressionists aimed to paint nature as it was. The advent of oil paint in tubes allowed them to paint outdoors directly from their subjects(4). Given that the effects of light outdoors are constantly changing, they had to paint rapidly to record their subjective responses. This resulted in bold brushstrokes and dabs of colour rather than the subtle graduations and glazing techniques favoured by the academic establishment of the time.  The impressionists were more interested in the effects of changing light that the 'local colour' of their subjects. For example Monet painted a series of paintings of Rouen Cathedral which is composed of quite colourless stone. He painted it at different times of day and under differing weather conditions resulting in very different paintings of the same subject. The skilful juxtaposition of colours achieves both modelling of the structure and vibrant yet harmonious colour.

Click here for more details about Monet's approach in a previous research point.

Click here to see numerous examples of Monet's Rouen Cathedral series courtesy of Wikipedia

As I alluded to in the previous research point about Chevreul, the impressionists' reported aim of painting nature in her 'true colours' is probably an impossibility because each colour placed on the canvas has an influence on how adjacent colours are perceived. Nevertheless, their work represents a revolution in the approach to painting. 

Seurat and his fellow neo-impressionists wanted to take this process further via a scientific rather than a purely subjective approach. Seurat is quoted as writing, " Technique is the should and body of the art". (3) He has, therefore come to be described as a scientific artist, applying the physical laws of light and colour rather than relying on his impressions. 
Closer reading of the literature shows that he wasn't really up to date with with all the scientific optical and colour theory of his day, preferring toe stick with Chevreul's theories rather than the more up-to date publications of Heimholtz and Ogden Rood. This was probably because he was very interested in colour harmony and Chevreul gave easy to follow rules for the harmonious combination of colours. However, John Gage writes:

" His painterly sensitivity and technical ingenuity nevertheless enabled him to extract from the theoretical literature a number of simple concepts and put them to work in the formation of a new style, avoiding many of the pitfalls that situations of such enormous complexity were bound to present" (3)

Seurat was an experimenter. He continually modified his technique as he made new discoveries. He described his working method as follows:

"The means of expression is the optical mixture of tonal values and colours (both local colour and the colour of the light source, be it sun, oil lamps, gas etc). That us to say the optical mixture of lights and their reactions (shadows) in accordance with the laws of contrast , gradation and irradiation."

Seurat called himself an 'impressioniste luministe'. It is thought that he hoped that the dotted technique, interspersing contrasting colours would give greater luminosity to his work. This approach has subsequently been criticised, based on the fact that optical mixture of complementary colours, rather than providing luminosty, actually reults in a greyish mixture. (3)

One of the flaws in Seurat's argument that his was a scientific approach is the fact that talked about 'local colour' in his explanation. What is perceived as 'local colour' is the light reflected back from an object - that is its appearance when illuminated by white light. Scientific theory of the day held that there was no such thing as local colour and Seurat can't have it both ways - he talks about local colour combined with the colour of the illuminating light but scientifically speaking if the colour of the illuminating light source changes, then the perceived 'local colour' would also change.

In his iconic work 'Sunday afternoon on the island of La Grande Jatte' (1884-6), there are established large areas of local tone and hue over which are superimposed the dotted transient effects of light. 





http://www.guggenheim-venice.it/inglese/exhibitions/avanguardie-parigine/avanguardie-parigine.html#prettyPhoto


References:

(1) Hornung, D. Colour: A workshop for artists and designers: Laurence King Publishing. 2005 (reprinted 2013)

(2) Petry, M. Nature Morte: Contemporary artists reinvigorate the Still-life tradition. Thames and Hudson. 2013

(3) Gage, G. Colour and Meaning: Art, Science and Symbolism. Thames and Hudson. 1999 (reprinted 2013)

(4)http://www.smithsonianmag.com/arts-culture/Never-Underestimate-the-Power-of-a-Paint-Tube-204116801.html

(5)Andrews, M.  Landscape and Western Art :Oxford History of Western Art. Oxford University Press 1999


(6) Anderson, J.  Monet. Grange Books. Regency House Publishing 2007.

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