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General image contrast adjustment

Over-all contrast control

Exclude all image contrast greatly affects its success. Some subjects such as engineering drawings or pictures of machines may need a very high contrast that may reach black and white only in the image with gray tones. Usually, images with high contrast suggest intensity, rigor, roughness, and strength, and that is why we prefer to use this high contrast in soldiers, wars, workers, rugged mountains, etc.. As for images with low contrast, they suggest softness, femininity, calmness, and tranquility, and therefore we prefer to use it in pictures of children, calm landscapes, etc.. As for Pictures with medium contrast is what we prefer to use in most cases, where the subject is a medium between intensity, pictures of women, and calmness.

And you can control the degree of contrast of the image by using several means: such as using sensitive paper with different degrees of contrast or sensitive paper with variable contrast, and we find that companies produce four, five, or six degrees of contrast. The same scenes, and we can also control the degree of contrast during development, printing, and enlargement by installing different solutions, as well as the relationship between exposure time and exposure time.

Show. We find that a longer exposure with a short exposure time leads to a lower contrast, while a relatively short exposure with a longer exposure time leads to an increase in contrast.

variance

Local Contrast control

Contrast occurs in many negatives that the contrast is high and low at the same time! how ? For example, when photographing a person's face in bright sunlight, if the contrast between the lighted part and the dark part of the face is not reduced by lighting the shadows open, see the book Photography is Science and Art, we will find a sharp difference between these two areas. At the same time, we find that the contrast between the features of the dark region is very small. As well as the contrast between the features of the illuminated area. If this negative is enlarged on sensitive, low-contrast paper, it will lead to an image with moderate contrast between the light part and the dark part. However, the contrast between the elements of the features within the range of the bright region as well as within the range of the dark region will be very low, which leads to flattening of the image (the disappearance of stereoscopic elements).

The simplest way to make a good image is to print the image on paper with more contrast than the average so that the contrast appears within the regions and reduce the contrast between the dark region and the light region by shading the shadow areas or burning the lighting areas. .