تصحيح ألوان الصور الموجبة بطريق الحذف .. كتاب التصوير الملون

Color correction of positive images by deletion

As mentioned before, a single light source is used in this method, and three filters with complementary colors are placed in the path of its rays (yellow, scarlet, and cyan). They are filters with colors similar to those pigments that originate in the three sensitive layers of the colored film. It is customary to use 33 filters in this way, including 11 yellow, 11 magenta, and 11 Cain, and the intensity of each filter in each group differs from the other. A filter is distinguished from another by numbers that may be written or engraved in the filter glass. These numbers are as follows: Between and the number 100 indicates a filter with a high degree of density, while the number E indicates the lowest degree of density. these filters.

In some cases, a set of filters, up to 60 filters, is used for the purposes of printing color films. The thirty-three filters are made in any of the following forms:

(a) Gelatine filters (b) as chips of gelatin pressed between two sheets of glass. As for the area of ​​this type of filter, it varies according to the size of the magnifier that we use. It may be (10 x 10 cm) or (12 x 12 cm) or (16 cm) or (18 x 18 cm). It is usual to find special signs on the filter, in a specific order, to indicate the color of the filter and the degree of its density. These signs are in the form of two short dashes and a number. The number indicates the density of the filter. As for its color, it is indicated by placing the number in relation to the two dashes. We can explain this in a simple way if we mention the following order indicating each of the three digits: ~19 x 19)
code

thus

50

Rose like this

Sian

yellow cochineal;

So if he put

It indicates a scarlet filter of its intensity.

And if put

It indicates a filter of cyan density.

If the code is put like this - - - -

- (50) It indicates a yellow filter of density 50

These numbers indicating the density were not placed arbitrarily, as if we combine two scarlet filters, one of them (- 30-) and the other (- 20-), it is certain that their density together will be equal to another scarlet filter, which we symbolize with the following symbol (1) (- 50-).