Monday, October 27, 2008

light and illumination


In the first section of Arnheim’s chapter on “Light” he discusses the experience of light. This idea has always fascinated me and I appreciated when Arnheim wrote that


the luminosity of a house, a tree, or a book on the table does not
appear to the eye as a gift from a distant source. At most, the light
of the day or of a lamp will seem to call forth the brightness of
things, as a match ignites a pile of wood. Things are less bright
than the sun and the sky, but not different in principle. They are
weaker luminaries. (Arnheim 304)


The very attempt at conveying light in a work of art seems more possible with an understanding such as this. Now that we know objects can be luminaries we can imagine them as a light source rather than only a reflective surface. The paradox is that light can never be conveyed in a work of art to the degree it is experienced by our eyesight. Livingstone illustrates this effectively with juxtaposing her actual experience of seeing colored blocks to the picture of the same blocks in her book. She writes, “No matter how good the photographic paper I use, I cannot achieve an adequate range of luminances for all the colors simultaneously!”


Reading in Arnheim further he points out that the “brightness” of an object is determined by its “setting” and he quotes Leon Battista Alberti, who said that “thus all things are known by comparison.” (306) In works of art there is not a source of light only a depiction of it, this reminds me of the color theory course I did last year. Based on Joseph Albers approach we did exercises on color intensity. I learned that a very dark color can appear bright based on where it is located. For example in Alber’s book he gives a good visual of this with a gradation study of white to dark grey placed on a light grey background can give the illusion of the background where the dark matter is placed is lighter than the background where the white matter is placed although we realize the background is all the same color. (Albers 80)


When Arnheim introduces illumination the explanations get murky for me. This is what I believe Arnheim is getting at when he wrote about illumination. Arnheim said “illumination is the perceivable imposition of a light gradient upon the object brightness and object colors in the setting.” (Arnheim 310) While the object retains its inherent color it none the less will appear to be composed of various colors when illuminated. The Fauvist and then the Impressionist utilized this technique. Arnheim quotes Cezanne’s letter to the artist Emile Bonnard, “Light does not exist for the painter”. This seems to be a startling statement since so many painters before and after Cezanne’s time devoted their lives to conveying light in their works.


The last part of Arnheim’s section on light when he discusses the symbolism of light epitomizes why some artist divest their creative time in conveying light. The idea that light is an active player on the canvas is a powerful one. This makes me think of works by Kandinsky. In his Several Circles many of the spheres seem light and floaty, another, a dominant black sphere appears galactic and spatial, like matter compressed. Some of the spheres appear to be “light sources” while the black sphere seems one which a viewer could dive into and be surrounded by a sea of black space. The black sphere also makes the blue sphere appear brighter and the halo around it makes it a floating orb. The viewer then becomes a little unsettled because how can one jump into the black sphere if it is placed on top of the floating blue orb. Arnheim would probably agree that this is the uncanny effect of light utilized by an artist who knew very well what his objectives were.

Sunday, October 26, 2008

Light and Illusion

In reading Livingstone’s book, I am constantly in awe of the images reproduced within the pages, but I was particularly struck by the Ingres painting on pages 126 and 127 entitled “Princesse Albert de Broglie, nee Josephine-Eleonor-Marie-Pauline de Galard de Brassac de Bearn”. Livingstone says that Ingres has “taken luminance to a new level” and “It is difficult to tell that the black-and-white version is not a photograph of the woman herself, rather than a photograph of the painting.” (Livingstone page 125) In careful reading of these statements (and others throughout the chapter), I realized that Livingstone places a heavy emphasis on the comparison of equiluminant representations of the same picture. In this chapter [8] specifically, she seems inclined to trust the monochromatic version of the piece more, in terms of spatial information it is giving the viewer. This is interesting to me because as she has very well noted, this is not how things occur in reality. “But it is impossible to consciously see only the luminance version of a scene or painting; we cannot simply see with that part of the visual system…” (Livingstone page 110)
This discrepancy correlates to an idea Arnheim discusses briefly in his chapter on light (chapter six). “Even so, we have trained ourselves to rely on knowledge rather than our sense of sight to such an extent that it takes accounts by the naïve and the artists to make us realize what we see.” (Arnheim page 305) This disparity between what we perceptually believe to be true and what is actually going on to cause us to perceive stimuli in one way over another lends itself to the idea of illusion. Prior to these chapters on light I would become frustrated whenever an author would use the word illusion. I thought this to be an inappropriate description of art. It is with the theories on the way light works that “illusion” becomes more appropriate to me. As Arnheim explains to us, the child’s notion of light is something that becomes terminated by darkness. He then goes on to describe how physicists and other “knowledgeable people” view the way light works in the exact opposite way. This implies that in this specific topic, the explanation of how it really works contradicts the way we perceive it to work intuitively. And, as Livinstone clearly accentuates, this offers a difficult task to the artist attempting to use shading in order to create reality-based depth. Therefore, when an artist accomplishes this task well (as Ingres does in the portrait on page 126), I believe it now to be more appropriate to call this an illusion.

Luminance

While reading Livingstone, Chapter 8, on luminance, I found it surprising to read that it is nearly impossible to accurately reproduce luminance in any kind of visual representation.
“No matter how good the photographic paper I use, I cannot achieve an adequate range of luminances for all the colors simultaneously! If the picture is made light enough to show the shadows on the black block, the yellow is so light that its shading doesn’t show, and the light colors appear too desaturated; if the picture is dark enough to show most of the colors accurately, the black is too dark to show shadows.”

She goes on to point out that in the picture in the book, you cannot see the luminance gradation on the yellow block. This really blew my mind because I normally think of photography as being able to capture visual images incredibly accurately. However, this is the one inevitable flaw of all visual representation. There are simply too many gradations of color due to luminance in the real world for them all to be accurately represented in an artist’s rendition.

It is also very interesting to see how different artists coped with this struggle. As Livingstone shows us with the multiple renditions of the Madonna’s red-and-blue cloak, the attempts to achieve accurate luminance are varied, yet none represent an accurate depiction, especially when placed next to the Christ Child, whose robes are significantly lighter in color and therefore show significantly more contrast between color and shadow.

However, according to John Shearman, Leonardo da Vinci was the first artist to achieve tonal unity. Da Vinci wrote, “Remember, painter, to dress your figures in lighter colors, darker colors will make lesser relief and be little apparent from a distance. And this is because the shadows of all things are dark, and if you make a garment dark, there will be little variety between the light and darks, while with light colors there will be greater variety.” He also did manage to vary the luminance of his colors without changing their saturation. Of course he did. He’s Leonardo da Vinci!

Light, Shadow, and Truth.

Reading Art and Visual Perception has made me reconsider the definition of an optical illusion. In the light chapter, I discovered just how many of the everyday visual experiences we take to be "optical truth" are actually "optical illusions," in that our perception of the world around us conceals the reality of what we are seeing. Light does not seem to emanate solely from the sun, but from all the objects that sunlight touches. Shadows do not seem to be the absence of light, but to have a substance all to themselves. The sensation of brightness we experience in an object can change dramatically based on its relation to other objects, just as colors can seem to change according to their context according to the laws of simultaneous contrast. As Leon Battista Alberti stated, "[A]ll things are known by comparison."

In the realm of art, the limited and distorted way our senses perceive the world influences our depiction of it. The result is the production of art that "looks" realistic to us, but does not treat light and shadow in realistic ways. This idea - that in order to make a picture "realistic," an artist must make it less like reality - was baffling to me. So was the revelation in Livingstone's chapter 8 that "[t]he range of luminances (contrast) in a given scene is almost always enormously larger than the range of values an artist can achieve using pigments" (111). It seemed difficult to believe that art could be so limited, given the wide range of expressions that artists have been able to achieve over the centuries. A startlingly realistic-looking painting such as Ingres' Princess Albert de Broglie does not seem to be lacking anything in terms of brightness and contrast. And what about color photographs? Like most people, I have always assumed photography to be an extremely accurate method of recording a scene. A color photograph that has not been manipulated should portray its subjects exactly as they appeared. Yet the limitations of photography have always been clear; I simply hadn't thought about them that much. Even the best photographs of a beautiful day, for example, seem to fall short in recreating the blueness of the sky or the golden quality of the sunshine that I remember. There are great differences between reality and the photograph's representation of it. We ignore these, however, and simply assume that there is no more accurate way of capturing images. Arnheim seems dedicated to illuminating the advantages that other methods of depiction have over our traditional Western, perspectival, "realistic" modes of representation.

When it comes to the interpretation of human perception, Arnheim also works to dissolve our Western presumption that we know better than any other culture. Societies that believe their shadows to be a mystical representation of themselves and will go to great lengths to avoid "losing" their shadows in the light of midday are not "wrong," says Arnheim. He writes, "Human thinking, perceptual as well as intellectual, seeks the causes of happenings as close to the place of their effects as possible." The Western interpretation of a shadow as the absence of light is farther from our perceptual truth than that of these African societies. The impression that a shadow takes up space may be an optical illusion, but "optical illusion is optical truth." Intellectual knowledge often conflicts with this truth, but it doesn't make it any less "correct" - just as a so-called "primitive" or cubist depiction of an object that ignores Western laws of depth and perspective are not any less true to reality than the "realistic" means of portrayal invented during the Renaissance.

The idea of "optical illusion" vs. "optical truth" relates to my conference work. I've been studying very early art, including Egyptian art that seems - to the modern Westerner - flat and unrealistic. Yet the Egyptians formulated their very specific style of representation in order to achieve the sorts of images that would be most accessible to the human eye - that is, the most realistic. They would not have drawn a square pool as viewed from one specific point of view and using the laws of perspective. Such a method would result in a square pool that was not square. Egyptian artists drew square ponds as squares, human heads as seen from the side, and trees as seen straight on. Every choice about how to depict an object was based on the need to make them instantly recognizable - and it worked. Even to the Western eye that is accustomed to seeing depicted scenes in perspective, with one point of view, Egyptian art is easy to understand. The figures in the art may look flat and strange, but it is clear what they are.

The history of Western art has been the process of distorting reality in order to make images more realistic. This is an irony that is well represented in the paintings of Cezanne and Titian that Arnheim mentions, in which portions of buildings or a face are darkened in order to contrast better with a light background. These methods make these images look better to us, but are in fact "forced" and "against nature," according to Goethe (who also stated that the products of such methods are "higher than nature"). It is not strange, though, that art distorts reality in order to make it realistic, when we consider the fact that our own vision distorts reality in order to highlight what is important for us to see in evolutionary terms.

Knowing that the distortion of art mirrors the distortion of perception, we should be more open to the range of artistic expression present in cultures across the world. Their art may not be realistic, but neither is ours. The difference is in the fact that non-Western art is not so limited by the need for so-called realism that it must ignore optical and cultural truths. An African mask, for example, may not seem to represent how a face "looks." Rather, it represents what a face IS to the people who created it.

Let there be Light

It's amazing to me how important light is to our visual perception system, even though we are often not consciously aware that we are looking at light (i.e. When we are in the shadows of a room). Light is one of the “first causes of perception” (Arnheim, pg. 303). Without light, we cannot see.

Our ability to distinguish the luminance or brightness of an object is related to the context of what's around it. For instance, the man in figure 224 (Arnheim, pg. 308) is seen as in shadows relative to the woman, rather than having darker skin than the woman. One of the reasons for this interpretation is that his cloak is also engulfed in shadows, showing that the whole body is situated in a place of low light in the picture. If his clothes were not shadowed, then it would be more arguable to interpret his darkened face as darker skin.

I am not an artist (other than two art classes taken in high school), so I'm incredibly impressed, knowing now, how hard it is to separate the luminance and the color in our perception, that so many artists manage to balance the two perfectly (especially Leonardo Da Vinci). Jean-Auguste-Dominique Ingres' picture of Princess Albert de Broglie (Arnheim, pg.126-127) is impressive. The caption is right – it is difficult to tell that the black and white is not the photograph of a person; in fact, I think it is only the unnaturally white skin that gives it away. The dress is captured perfectly with the way that light reflects off the shimmery material.

Livingston outlines how our visual system is adapted to perceive more luminances even though the actual perceptual ability of the individual parts of our system are limited. The center/surround system allows us to easily distinguish the difference between sharp contrasts. Gradual changes are overlooked when distinct changes occur. In this way, we increase our ability to see luminance differences.

I am intrigued about the correlation that Livingston draws between luminance contrasts and depth perception in paintings. She says that the Cathedral paintings that look flatter are also the ones that have little luminance contrast in the analysis of the luminance profiles. This is due to the fact that the Where system is colorblind and sensitive only to luminance changes in seeing shapes from shading. “Thus, a low luminance contrast alone stimulates the Where system but not the What system” (Livingston, pg. 128).

The two paintings by Monet (Livingston, pg. 132-133) demonstrate what happens when the artwork stimulates primarily the Where system. The objects in the picture are not distinct, and it is only after studying the picture for some time that one can distinguish the objects at all. Despite the fuzzy quality of the objects, the depth relations of where the blurry objects are situated is clear. This is due to the low luminance contrast and lack of color contrast.

I found it particularly striking that Andre Derain understood that by utilizing the luminance differences to show depth, an artist was freed from using descriptive colors to work with expressive colors. This ability is due to the colorblind-ness of the Where system which sees depth.