منتجات التصوير الملون ١_a .. كتاب التصوير للهواة

The second year

Color photography Chapter 1 Products of color photography

introduction

The word photography is derived from the two Greek words (painting with light). Imagination is one of the most common ways to convey feelings, as there is an importance in the world of photography in modern civilization, and there is no effective human field at the present time, whether industry, science, recreation, or graphic news, printing and recording family history, without touching photography products.

Photography has a long history, from the beginning of the discovery of the effect of light on silver salts until our present time. Photography has emerged from the scope of the hobby to a science in itself and imposed itself on the branches of science and its practitioners in universities.
Europe that some universities have even begun to grant a doctorate degree in photography

Because this world witnessed a great development, especially after the year 1900, when color replaced black and white, and the imaging products industry became one of the very important and popular industries, especially color, which began to definitively replace black and white, and color animated films 99% replaced black and white and images (white - Black) The static found its way to disappearance.

And compounds are imaging, which is the process of producing a visible image based on the action of light or other energy sources in sensitive materials. The word “light” will include the part of the electromagnetic spectrum extending from the visible to the infrared region. Sensitive materials used are diazo silver halides and zinc oxide. Silver halides are widely used as a sensitive material, and these materials have a natural sensitivity to ultraviolet rays and blue rays, and their sensitivity to green, red, and infrared rays is weak (neglected) unless a special sensitivity to this region is made that includes adsorption of so-called sensitive dyes on its surface or sulfur compounds and sensitivity to blue and green And red is especially important in color photography.

color imaging theory

The foundation In 1855, Clark Maxwell laid down a rule that is the colored imaging stone by adding three colors of rays to each other and mixing them in specific proportions. Red, green, and Maxwell used to project his colors onto a black board, and he chose it specifically because it does not reflect any rays at all, and any additional color appears after dropping the colors, but as a result of adding the colors together. In fact, this fact seems true even if the board is white like a movie screen, and even if It was projected onto the retina of the human eye, and this rule was used in the production of color images, and Clark made a table of colors that we summarize as follows: rays (red + green + blue) = = white rays

Blue + green = cyan. Green + Red = Yellow Red + Blue = Crimson The complementary color is one that, when added to another, gives white. Red + Cyan = White Green + Crimson = White

Yellow minus blue is called blue

Blue minus yellow is called blue

There are two important theories in color photography, which we summarize as follows:

1- The theory of color imaging by adding method:

Preservation, although all the colors that we perceive in nature with our eyes can arise from mixing the three primary colors (red, green, and blue) in different proportions. red, green, blue) and separating each element alone from the other two elements and then returning all these elements in the same proportions that were originally in nature. It was obvious during the stages of color photography research that the search for a way to separate the natural color elements from each other begins with some proportions. This was achieved by photographing three consecutive times on three sensitive films with the use of color-separating filters. The first time is done through a red filter placed in front or behind the lens, in the second with a green filter, and in the third with a blue filter. The colors of these filters must be very subjective, so the filter does not allow Any other light waves that contradict its color by passing through it, however, it is not possible to achieve this condition in the ideal way that we require. After photographing and showing these images, we get three negatives (black and white) that represent the first negative filming
Which the photographed subject bears from the color red, while the second represents the amount that the subject bears from green, while the third represents all the blue colors in that subject, and where each negative has separated one color from the primary colors (red, green, blue) by which any color can be formed It was in the subject being photographed, so work was done to name it as (the negatives of color separation).

They are called negatives because, after imaging and display, they become carriers of opposite proportions of the quantities of colors that were present in nature. Therefore, it is necessary to print these negatives to obtain three positive copies, which we will call color separation positives.

And it is a positive image that carries the correct proportions of one of the three primary colors from which the color of the landscape is formed. It is noted from them that the transparent areas represent a good amount of the primary color. If we see in the positive transparent image a gray area, this means that this area does not represent in nature a pure color, but a color mixed with another. The appearance of dense black parts in the positive transparent image also indicates that this part of the image represents in nature an area completely devoid of primary color. And if the positive transparent image was representative of the natural blue colors and a black area appeared in it, then this means that the subject that we photographed was free of blue color in this part of the image. If this black distance is repeated in positives