مقاييس درجة حرارة اللون .. كتاب التصوير الملون ، عبد الفتاح رياض

Color temperature scales:

These measurements are based on a theory summed up in the fact that white rays consist of three equal parts of red, green and blue rays. Or how blue it is, in other words, it becomes easy to measure the color temperature of the rays.

Radiation through and based on the foregoing, I made gauges (Fig. (21) consisting in their simplest form of an electric photocell connected to a microampere and a microammeter, and in front of this photocell there is a round disk with one half of it a red filter and the other half a blue filter. In front of the two filters there may be a diafragm It controls the intensity of the light falling on the filters.There is also a screen to determine the passage of the red filter alone or through the blue filter alone.The photoelectric cell measures the amount of each of the red rays (which pass through the red filter) and then the blue rays (which pass through the blue filter). The two quantities, the rays are white, and this does not move the pointer of the micrometer, ampere, and meter.” If one of them is greater than the other, the pointer moves in front of written signs and numbers indicating the color temperature of the rays, estimated in Kelvin units.

The meter may have two photocells, one of which measures the amount of blue rays, and the other measures the amount of red rays.

Ray forger identification visor

through the red filter alone

Or only through the blue filter

photoelectric cell.

Disc holds two filters one

Blue and the other Ahmed

Figure 21: Radiation color temperature scale

D In addition to the Kelvin degrees, which directly indicate the color temperature of the rays, we often find other units on the division of the scale, namely Mired or Decamered (and we will talk about them). These units give us a direct indication of the degree of density and color of the filter, which is suitable for adjusting the color temperature of the rays as much as we desire.

It is possible to check the correctness of the filter selection, by placing a photodiode and then pointing the meter towards the light source. e in front of the cell

And it is his reference in response to the first question. We say that there are psychological factors that affect the ability of the eye to perceive the difference in color when the spectral characteristics of the sources of light rays change (i.e. when the color of the rays changes). This difference will not be as clear as we might expect, with regard to that phenomenon known as (1) Approximate Color Constancy. This phenomenon is due to the fact that man thinks of color as a fixed fact that does not change. Look at it carefully. If an individual looks at a surface of a certain color, such as green leaves or blue flowers, in daylight, this color is imprinted in his mind, forming a mental idea about the color of these things. This idea often becomes a constant mental impression. Mental Impression is related to the color of these objects, and although this mental impression has grown in conditions of vision in daylight, it often remains constant even if the object is seen.

Does the human eye have the ability to perceive the change in the colors of objects as a result of the different colors of the rays of light sources? Does this change in color appear clear when filming with color films?

Death, and we mentioned that this mental impression often remains constant despite seeing under x-rays. A light source with different spectral characteristics, and we did not mention that this impression remains constant at all times, as the reality is that there are other cases in which we realize the color change if the spectral characteristics of the light-ray source change. Here are examples of these other cases:

Under the rays of another light source that differs in its spectral characteristics from the characteristics of the white rays of the day, and therefore we will still perceive the colors of the leaves of trees as green and the blue flowers as almost the same blue, even if we see them in nature during sunset when the color of the rays tends to be red with yellow.

(1) When comparing the color of . In daylight or in the light of tungsten lamps, then its color is under the light of a fluorescent lamp, which is characterized by a significant decrease in the percentage of red and yellow light waves, while the percentage of blue light waves emitted from it increases, which clearly affects the color of some colored pigments, so that their colors appear to change. In light of these sources, body 2

(b) When comparing the color of an object while it is in a medium of a certain color with its color in a medium of another colour

(C) When matching the colors of the surfaces, which are characterized by sharp peaks spectral reflectance curves in some parts, and severe depressions in other parts. That is, in a simplified expression, those surfaces whose spectral colors are pure and not mixed with neighboring spectral colors.

It is clear that it follows from the previous fact that a clear difference is seen between the color of the surface in the light of a specific source and its color under the rays of another source with different spectral properties.
In response to the second question, we say: Color sensitive films only record the colors of the rays reflected on objects, so the color of the image changes clearly if the spectral characteristics of the radiation sources change. If we combine different light sources in their spectral characteristics (such as daylight and the rays of the tungsten lamp) to photograph one body, then we see in the color image blue on the side illuminated by daylight, and yellow with redness on the side illuminated by the tungsten lamp. We have already mentioned that the factories that produce these films are films prepared for filming in daylight and others for filming in the light of industrial sources. And if it is necessary to use one of these types of imaging in conditions other than the one for which it was prepared, then it is necessary to use filters that adjust the color temperature of the rays, which we will talk about on pages 64-71.

For each degree of caffeine (Kelvin) there is another value associated with it known as (the Mired Value) and it is equal to the degrees of Kelvin.

his temperature

Maid value:

Some color temperature meters carry two divisions, one of which shows the color temperature estimated in Kelvin units, and is called the Kelvin Scale. The second division is indicative of the Mired Scale value. For the above or refer to Figure 22 on p. 59 or to the following table and to me No. 4 on p.

(1) This nomenclature was taken from the first letters of and means «miniature reverse degrees, as the value of the mird decreases as the degree of the kelvin increases. MI RE D MICRO RECIPROCAL DEGREE