Tonal Paradox – from Three-Dimensionality to the PlaneTonal paradox – from three-dimensionality to the plane.
Every artist, especially one working from life, has faced the question – why, having at his disposal perfectly white and deep black paints, can he not fully reproduce the entire range of tonal differences found in nature? Why does everything on location appear voluminous and radiant, while the study brought back to the studio usually looks dull and gray?
It is well known that artistic paints, unlike the sun or a lamp, do not emit light themselves, but only reflect it. This already creates a huge difference from the actively glowing objects of nature.
But the main reason is different. The main reason is the fundamental difference between the three-dimensional world and the two-dimensional surface of the painting.
In three-dimensional space, light is distributed across the surfaces of objects extremely unevenly: one part may be dazzlingly illuminated, while another is immersed in the deepest shadow. Human vision, thanks to its ability to adapt, easily perceives this enormous dynamic range (the difference between light and shadow can easily reach 1000:1 or
more).
The paradox is that our paints themselves are quite capable of reproducing the tonal brightness and depth of objects if they are placed in the same lighting conditions as the objects in nature.
Imagine – if we painted birch bark with titanium white. Lit by the sun, it would become incredibly bright, perhaps the brightest object in the forest (except, of course, for the sun itself and its highlights). And if we covered the ground under a dense, shady bush with black paint, that place would look like a black hole.
However, a painting is a flat, two-dimensional surface. It cannot imitate the volumetric distribution of light and shadow. On the plane of the canvas it is impossible to simultaneously create areas brightly lit by the sun and areas immersed in deep shadow.
The
tonal range available to paints is at most 30:1 (high-quality titanium white can reflect up to 97% of incident light, while the darkest black paints reflect about 3%).
At the same time, on a plane this ratio remains unchanged under any lighting. Whatever conditions the study is placed in – under the sun, in shade, or indoors – the difference between the lightest and the darkest area will not exceed this 30:1.
The same limitation applies when trying to compare paint with nature directly. Whatever the lighting, the difference between white and black paint on any flat surface will remain unchanged – about 30:1. We may turn the palette, bring it closer to the object, or change the angle, but if the entire surface is evenly lit, the ratio of reflected light between the white and black areas will not change.
Take an example: an artist is painting a birch tree lit by the sun and its own shadow in thick grass.
If the comparison plane is turned toward the sun, he can easily pick white paint that matches the brightness of the illuminated side of the trunk. But if he tries to take the deep shadow – even the darkest paint will prove too light. Black paint lit by the sun will appear brighter than the actual shadow under the bush. In this position, comparison with shadows becomes impossible.
If the plane is turned into the shade, the opposite happens: it becomes possible to match the color of shadows and mid-tones accurately, but the illuminated birch bark can no longer be matched – white paint in the shade will appear darker than the sunlit trunk.
This is the key point: if the sample plane is kept in one fixed position, one can accurately match either the light or the shadow, but not both at the same time. Such is the limitation of the very physics of light.
So how can an artist accurately match color under conditions of high contrast?
The solution is dynamic exposure: turning the plane toward the specific light zone.
Color comparison must take place under adaptive, dynamically changing exposure on the sample surface.
That is, the paint sample should be lit by the sun or the sky when comparing with bright objects, and darkened when comparing with mid-tones and shadows.
In practice this means that:
– for bright areas the plane must be turned toward the light,
– for mid-tones of nature it must be turned away from direct illumination,
– for shadows it must be turned fully into the shade.
A short rule – the lighter the object, the brighter the exposure on the paint sample. And vice versa.
It is precisely this technique that allows one to drastically “stretch” the working tonal range of paints far beyond 30:1, making direct comparison possible even under conditions of extreme contrasts.
Incidentally, this simple but critically important condition – variable exposure of the comparison plane – was for a long time not recognized by artists, and in fact slowed down the spread of the method of direct color comparison in painting.
Fixed and Dynamic ExposureThe method of direct comparison at a distance works in two modes: with fixed and with dynamic exposure.
(Exposure in this context means the level of illumination of the plane on which the paint sample is placed.)
With fixed exposure it does not change.
With dynamic exposure the artist turns the plane toward the light or into the shade, adjusting it to the brightness of the area being compared.
Fixed exposure works perfectly in conditions where the scene fits within the tonal range of the paints themselves, that is about 30:1 – from white to black. For example, when working with two-dimensional objects such as a photograph, an electronic display, or when reworking a study or painting.
Fixed exposure can also be used from life in the studio (still life, portrait), when the light is distributed evenly and there are no sharp, deep shadows in the setup. When white paint is comparable in brightness to the lightest areas of nature, and black to the darkest shadows.
Fixed exposure is a complete comparison mode, which makes it possible to match all three parameters at once – tone, color, and saturation across the entire range, from the lightest to the darkest area.
Dynamic exposure is a working compromise necessary when dealing with three-dimensional nature and strong contrasts.
Because of physical limitations, tone here unfortunately cannot be taken directly. But if the illumination of the plane is adjusted to the brightness of the compared area of nature, color and saturation can be determined precisely.
The tone itself is then built manually – through the system of relationships on the canvas.
This technique makes it possible to radically extend the working range of direct comparison far beyond 30:1, while still remaining within the capabilities of the paints themselves.
But on the surface of the study all these “stretched” brightness values are once again perceived as the familiar 30:1.
By the way, this technique can also be consciously used by the artist – for example, deliberately turning the plane fully into the shade so that comparison requires lightening the paint. This leads to the final color becoming lighter, and the shadows on the painting do not “collapse” into blackness, but retain color saturation and legibility. Thus, exposure adjustment works not only as a means of accurate comparison, but also as a tool of tonal correction already at the stage of color selection.
(A
special tool has currently been developed for artists that allows the use of direct comparisons with consideration for exposure adjustment.)