تأثير لون الأشعة المنعكسة من السماء في لون مناطق الظلال في الصورة الملونة .

The effect of the color of the rays reflected from the sky on the color of the shadows in the color image if the imaging was in daylight:

In places that are not illuminated by direct rays in the shadows of a building, for example, two factors control the color of the light rays, and these two factors are:

(a) The color of the rays reflected from the sky.

(b) The colors of the rays reflected from neighboring colored objects.

In order to realize the effect of this first factor alone, which is the color of the rays reflected from the sky when photographing with a color film, we will assume that the objects close to the object being photographed have a completely white matte color, and thus its color is affected only by the color of the rays reflected from the sky. If the sky is clear blue, then it is certain that the rays of daylight tend to be bluish, and thus it may cause a blue tinge to cover the image in general, or it may cover only some parts of it. Therefore, we find that the shadows areas on which direct sunlight did not fall appear blue in the pictures (1).

This phenomenon appears clear when photographing people in portraits with color film, so the shadows appear bluish sometimes, as is evident in the images of glossy black surfaces such as black cars and black hair, so some of its bright parts appear in high lights in a blue color, and some parts of landscape images may be covered with this. the colour blue . It cannot be said that the appearance of this blue color in some parts of the image is always something that is disliked, rather it is sometimes loved and would give the image an aesthetic value. The effect of this blueness is less if there are thick white clouds in the sky.

When photographing with a color film near the sea, or on high mountains that are covered with snow (especially when photographing distant places with telephoto lenses), it is likely that we will find the image covered with an intense blue tint due to the increase in the percentage of ultraviolet (unseen) radiation in these places. They are rays that would have a strong effect on sensitive films (black and white) and color alike, despite the inability of the human eye to sense them, and it is also possible that the image is not sharp due to the different light wavelengths of all visible and ultraviolet rays (1) In such cases, it is necessary to place in front of the lens a filter that absorbs ultraviolet rays (which is a transparent filter that does not affect the colors of the image in any way), and it is the filter known as the Aerial Haze Filter.

The effect of rays reflected from nearby colored surfaces on the color of the color image:

The colors of the surfaces and objects close to the photographed subject also have a great influence in color photographs (2), as the green grass in a garden reflects green rays that appear clear on a white shirt or robe that appears in the picture, and the red robe reflects red rays that appear clearly in people (chin and neck), and water Blue rays reflect blue on the pictures of white boats. Although the effect of the reflected colored rays is usually desirable if the colored surface that caused this effect is apparent in the image, such as the appearance of green weeds that cause greening of some parts of the image, but we cannot make that a general rule, because the decisive factor in that is the circumstances of each image accordingly. The intensity and suitability of the colors of the reflected rays to the colors of the photographed subject.