I am currently reading a book on painting techniques by artist Virgil Elliott. I’m discovering all kinds of interesting things that I hadn’t thought about before. It’s what in English is called connecting the dots.
For instance, consider an apple on a table in the courtyard with sunlight falling on it. What color is the apple’s shadow? The color of the shadow is determined by a mixture of the secondary light source’s color, the apple’s own color, and the color of the table on which the apple’s shadow falls. The color of the secondary light source is blue. Why blue? Because shorter wavelengths scatter better, and the shortest we see is blue. If we could see UV, the sky would be UV-colored. Thus, blue light comes from the sky and falls into the apple’s shadow. Therefore, the shadow is not pitch black as it would be on the Moon. In an indoor setting, however, the shadows carry the color of the walls, mixing further with the color of the apple and the color of the table. But still, most of the energy comes from the sky, so the shadow is blue. I sort of understood this intuitively, and even used it, but never really thought it through properly.
Okay, but why does human vision perceive sunlight with a slight tinge of yellow? For example, if you look at the sun from space, you would see white sunlight. When sunlight passes through Earth’s atmosphere, shorter waves (blue and violet) scatter much more by air molecules and particles in the atmosphere than the longer waves (red and yellow). This means that direct sunlight reaching the Earth’s surface has more of a yellow spectrum, compared to when the light is not distorted by the atmosphere.
Reading further, in the chapter about Venetian techniques, I understand another thing that finally explains why artworks on a computer screen look altogether different. In the past, artists were very particular about color. A painting could be worked on for years. Paints were applied in layers, each allowed to dry before new, semi-transparent top layers were added. Light, entering such layered shadows, gets trapped in it. Much of this light does not escape easily, increasing the contrast. What does escape, however, is tinted — and this tint depends largely on the viewing angle and the angle at which light falls. As a result, it produces shades that simply do not exist in the paint pigments.
In other words, from the perspective of color rendering, a painting has not only pigments but another important attribute — the thickness of the layer of paint, and it’s this physical characteristic (well, apart from the pigments, of course) that determines the color we see at any given point. It’s not just about having green or blue pigment there. Eventually, if we see, say, a bunch of grapes, a 17th-18th-century artist had to do more than just place the right color pigment in the right spot; a proper underlying layer was needed, and on top of that, a dozen layers of semi-transparent oil, each shifting the color of the base through both pigments and reflection of light. Of course, no artist could control this molecular reflection adding harmonic colors, but by following the technology, an artist could achieve something unusual, refine it further by color, and end up with something unique that fits within the right color.
Hi, I'm Rauf Aliev. 