التصوير بالألوان .. كتاب فن التصوير الفوتوغرافي

Color photography

Before starting to study color films and color photography, it is useful to study light and color.
Color photography is based on the principles of light and colour.

Light is a type of electromagnetic wave such as those broadcast by radio and television, but it differs from it only in its length (radio waves range in length from a few centimeters to thousands of meters, while the wavelengths of light range from about 400 to 700 millimeters (*).
When radio waves encounter an electrical conductor, they are converted into an electric current. When the light waves enter the eye, electrochemical transformations occur in it, which in turn generate electrical impulses that enter the brain, where the feeling of light or vision occurs.
Color is our reaction to the wavelength of light that we see. If the wavelength is relatively long, we see red light, and our reaction to the shortest light waves is seeing the violet color. And confined wavelengths of the rest of the colors between these two limits.

When a mixture of all visible wavelengths hits the retina, we see the color white. Sunlight or Nangistan lamp light (*) is an approximate mixture of all colours. So we say that white light is a mixture of all colors of light.

This can be demonstrated by decomposing the white light by means of a glass prism into its constituent wavelengths, by converting a beam of white sunlight, or any white light, into a glass prism as shown in Figure 1.
A prism refracts the rays, each according to its wavelength, so it refracts the shorter wave of violet color at the largest angle, and refracts the longer waves at a smaller angle. As a result, when the light comes out of the prism, it is not white light, but rather a spectrum of different colors in ranks according to their wavelengths. And this refraction is what you see from the rainbow, which is a phrase
A giant spectrum resulting from the refraction of white sunlight through water droplets suspended in the air on a day when the sky is raining and the sun is shining.

And we can install white color or white light by mixing suitable amounts of all colors or colored lights. And because the human eye responds to colors in a specific way, we do not need all the colors in order to arrange white, rather we need three colors: red, green and blue. If we mix these colors in equal quantities, we get white, so these colors are called the original colors of light, and any color can be combined by mixing an appropriate amount of these original colors.

Color photography uses these three primary colors to produce any subject in its full, natural colours.
If one of these original colors of white light is intercepted by a filter, then the mixture of the remaining two colors is called the complementary color, and it is so called because it complements a basic color to produce white light. In this sense, the complementary color can be considered the negative color of the primary color. Therefore, the negative of any color is a compound of colors that are the complementary colors of that color. Table (l) represents the three original colors and their complementary colors.

In order to prove the correctness of table l, let us take three projectors, each with one of the original colors, and project them on a white screen, where the three projections mix and the screen appears white, and where only two colors mix, the result is one of the complementary colors. (Fig. 2).