الألوان الأولية في التلفزة الملونة والات التصوير التلفزيوني الحديثة

Chapter II

Primary colors in color television and modern television cameras

introduction :

After the practical success of monochromatic television transmission and reception, which shows pictures and scenes in black and white. Using the gradient between these two colors according to the shades of color and lighting in the image. It transmits the details of the image, which is converted by the television camera into an electrical signal, and then transmitted via radio waves. And this success was an incentive for scientists to develop this device so that it receives colored images, similar to the primary color with which it was transmitted, so that the scenes and images are more lively, enjoyable and realistic, and this development must include all transmitting and receiving devices and machines

Photography and various departments. At the beginning, many technical difficulties arose, and soon they were solved one after the other until this strange device was manufactured, whose screen radiates with pictures and scenes.

Fun animated colour. The beginning of the use of color television in the early fifties of the century in the United States of America. Although the foundations of this theory based on colors
The three (red - green - blue) were developed by scientists such as Lomonosov - Young -

Fedrov.

A major development took place in the year 1960 by French and German scientists, and modern systems appeared such as the French (SECAM) system and the German (BAL) system, and a system was also developed

US NTSC.

1 - 2 The theory of colors and their wavelengths

The colors that we see in nature are many and varied, and our vision of things: It takes place as a result of the reflection of the rays from the visible thing and its return to the eye - the matter that we see is of a red color, which reflects only this color and absorbs all other colors of light. As well as blue, yellow, and others, as it absorbs all colors of light and reflects the color in which it appears in its usual color.

It is known that the sun is the most important source of natural light in our world and its rays that appear white are in fact a composite of the colors of the spectrum, which appears in the rainbow in some winter days. Sunlight can be analyzed by means of a glass prism that shines light on it via a reflecting mirror - and six colors of light are shown, which are red - orange - yellow - green - blue - violet - and this was proven by Newton since ancient times, Figure (2) - (1) and light in fact It is nothing but an electromagnetic wave that contains electro-magnetic energy, and each color has a specific frequency, and therefore it has a wavelength that is measured in microns (Fig. 2) (2) because its wavelength is very short and its frequency is very large. And there are rays that are not visible to the human eye, namely infrared and ultraviolet rays. It is called the invisible spectrum. This is similar to the sounds above the auditory and below the auditory that the human ear does not hear, while some animals or insects hear and feel them.

Primary colors in color television: The number of colors and color shades is too large to be counted. It was found that any color can be obtained if we mix two or three primary colors in correct proportions Which :

Red, and its symbol (Red), has a wavelength of 700 milli-microns and a frequency of um 10492 Hz
Green and its symbol (Green) has a wavelength of 546.1 milli-microns and a frequency of 1210560 Hz. Blue, and its symbol (B) Blue, has a wavelength of 638 milli-microns and a frequency of 638 x 10 Hz.

They are called primary colors and they are independent of each other, and none of them can be obtained by mixing the other two.
These three colors have been adopted in all television systems, so any scene whose colors are decomposed into these three colors in the television camera. These colors are then recombined into the color receiver screen valve.
mixing colors :

Obtaining natural colors depends on mixing the three primary colors in limited proportions. If we shine three light sources of red-green-blue colors on a wall or screen (Fig.
. Color chart: It shows the different colors and their wavelength in milli-microns, forming what looks like a tongue or a horseshoe, Figure (2-6) where the three primary colors are located on its corners approximately. And the other colors show how it relates to the base color. As for the internal colors that do not have external borders on the chart, they are composed of two basic colors, and the white color appears in the middle and is composed of limited proportions of the three colors red - green - blue. Any line that connects between the midpoint of the white and the outer edge of the figure shows the extent of color purity and saturation - the closer it is to the white, the less its saturation or purity - and the closer it is to the outer edge, the greater its saturation (Line (8). But if a line connects between two external colors, it Shows the colors that result from mixing them and the proximity of each color to the two mixed colors (line (B)

Color characteristics and the distinguishing properties of colors: A - hue: which determines the color and distinguishes it from other colors and has a specific frequency and wavelength - such as red - green - blue - yellow - white, the red color has the characteristic of rednes
The yellow color has the characteristic of yellowing. The blue color has the characteristic of blue.

B- Saturation or purity: It distinguishes a dark color from a light one - or a bright one from a bright one. The more it is mixed with white, the less its saturation becomes - for each color it gradually becomes white, so the percentage of saturation is zero (zero). The higher its concentration, the greater its saturation until it reaches full saturation, so it is bright in color, i.e. its saturation is 100%.

C - Brightness or Luminance: It is the intensity of light that reflects and shines from this color and reaches the eye. This element shows its effect even in black and white TV transmissions. We can call the adjective chromaticity or (chrominance) the hue and saturation of the color as stated in paragraphs (a) and (b).