The Complete Guide To What Is Contrast In Photography

Many amateurs might not know what is a contrast in photography is, if that’s what you are looking for, then you have come to the right article.
The contrast in the image is very beautiful in most cases (I say most of the time because there are cases where ambiguity is the goal of the image, so the photographer searches for blending and blurring more than contrast). Contrast may mean difference and distinction (for example: the level of students varies between weak, average and excellent) and reaches at its highest levels the complete contrast as well as the contradiction between white and black. The contrast may be moral sometimes, as do the happy and unhappy, and it is sometimes formal, as do the long and short, and it is sometimes color, as is the contrast between warm (red) and cold colors (blue). The contrast may also be in sharpness, as between what goes in and out of the depth of field.

The ability of the photographer to use contrast with all his concepts in the image is one of the secrets that only those who have mastered the art of photography know. Contrast, when used correctly (in addition to other composition elements), guides the viewer and determines how his eyes wander in the image.

What matters to us in today’s topic is the contrast of lighting in the picture. Since our topic is about processing, we will not talk about contrast before and during the capture of the image, but rather about enhancing the contrast while processing it in the digital lab. The contrast in the image is of two types:

1- General contrast: It is the contrast between shadows and lighting, regardless of their location in the image.

2- Local contrast: It is the contrast between adjacent shadows and lighting areas in the image.

In order to understand the difference between them well, let us take illustrations. Here is an image that has been processed twice, once with increasing global contrast and once with increasing local contrast:

If we take the general contrast treatment, we will notice that the shadows became darker and the lighter areas became brighter, and although the pupil of the eye and its whiteness became more contrasted, the hair strands lost their contrast! Why? Because the general contrast does not give importance to the place of treatment, but only to the degree of illumination, as well as the effect on shadows and areas of brightness is very large, but the gray areas are not affected much.

Also Read: what is white balance in photography and how its used in a camera

Looking at the treatment of local contrast, we notice that the strands of hair have become more differentiated, and that the cheek and nose have become more embodied (feeling in three dimensions). The reason for this is that local asymmetry separates adjacent and originally distinct gradients in the image. We notice that the treatment of local contrast made the gray gradations in the shades of the nose darker due to their presence in the middle of the gradations of the lighter ones. As for the gray gradations in the locks of the hair, the treatment made them lighter and this is due to their presence between very dark gradients

What are the tools used to increase the general contrast?

Photographers use several tools to increase overall contrast based on their level of processing, as follows:

Brightness & Contrast

Despite the simplicity of this tool, it is the worst one at all, because it treats shadows and highlight equally regardless of their distribution in the image. This tool is excellent for beginners but I recommend moving to alternative levels as soon as possible.

Levels

This tool is acceptable to professionals, but it is not the best. Its advantage is that it enables the photographer to manipulate the shadows and brightness areas independently of each other (by moving the triangles below the graph). This tool also enables the photographer to increase or decrease gray lighting. The tool has other functions, but this is what we are interested in now. If you use this tool, you should make Brightness & Contrast a thing of the past.

Curves

The most powerful general contrast tool ever. It does everything you can, its predecessors and more. It enables you to increase or decrease the lighting of all lighting areas. If you control three points in the level tool, you can add as many control points as you want here. You can also control the way the effect moves between points. If you learn to use the tool well, you definitely do not need the Level tool.

The natural path for anyone learning to process is to switch from the Brightness / contrast tool to the Level and finally to the Curves tool. Of course, the Curves has other “supernatural” powers, but talking about it will take us away from our main topic.

What are the tools used to increase local variation?

Although many commercial tools are available, using the basic Photoshop tools gives you a more professional result because they are the least destructive to the image. In Photoshop, there are also many tactics, but the following two tools are most popular:

Unsharp mask

Some people may ask, why use a tool to sharpen the local contrast? Answer: digitally increasing sharpness is a kind of local variation! Are you surprised All there is to it is that the sharpness is an increase in local disparity, but on very narrow and limited areas. Therefore, we can call the digital sharpness by another name, which is “subtle local contrast.” And if you don’t believe it, try seeing the pixels in the sharpening areas as large as possible before and after the filter effect, and see what the filter did.

All you need to do to increase the local contrast is to use the Unsharp mask with slightly different settings. Start with the settings suggested in the illustration and then gradually change them until you reach the best result.

High Pass filter

This filter is very popular for increasing local contrast and 3D and it is the same filter used for the Dave Hill effect and similar effects. You make a copy of the image on a separate layer, apply this filter to it, and then change the Blending Mode to Softlight for the new layer. And the amount of the effect depends on the size of the image, and it is preferable to dilute the effect of the new layer using the Opacity.

You can also use global contrast to reduce blur, whether multicolor or monochrome.

The reason for using contrast for this is that it gives two effects:

1- Harden the shadows and lighter areas, giving more weight (and less detail) to the lighter areas and reducing detail in the shadow areas. It also brings part of the gradations of other regions towards white or black, which reduces gray tones and increases the proportion of shadows and lighter areas. This effect is often desirable and suitable for many pictures, but increasing it in an exaggerated manner is considered a desired effect by some portrait photographers.

2- It gives a slight percentage of saturation that is often required except in a few cases (as in the last example at the end of this topic).

The application of general contrast is useful for most pictures, but the method of applying it must be very careful because it destroys the image easily, and these things include the following:

1- Some pictures have large areas of very dark gradients, so the effect on those areas must be excluded or minimized because it kills the dark areas.

2- The same applies to areas of brightness, so beware of applying contrast to places of extreme brightness, because it kills details and produces color cracks.

Here we notice how the details in the shadows areas were negatively affected after increasing the general contrast:

The Curves tool becomes very important as it surpasses the Level tool in dealing with the two previous problems as it increases the contrast with a greater effect on the pre-light and pre-very dark areas, with a natural gradient between the image areas and with less effect on the areas sensitive to contrast.

There are cases when contrast is beneficial for some subjects and harmful for others. In this case, we must use masks so that we apply the effect only in the appropriate places and exclude other areas.

So, the summary of what we have mentioned so far is that increasing the general contrast has benefits and side effects (influenced by the issue of the flu vaccine!). We must exploit its benefits while avoiding its side effects by using the Curves tool or using masks or both together.

Now let’s turn to the local variance. What is its benefit? Local variance has two main benefits:

1- Highlighting the details of the topic if it is applied to narrow scales, such as increasing the intensity or increasing the sense of the features of the topic if we use a slightly wider scope

2- Three-dimensional highlighting of subjects, when applying contrast to a wide area of ​​shadows, where the increase in local contrast makes the transition between shadow and light more intense, which makes the objectification of the body more complete. This will be illustrated in the next example

Now that we have explained the benefits of the two types, we return to our basic question: Which of them shall we apply?

After reading what we mentioned above, it became clear that the benefits of each of them are different and their results are complementary and not mutually exclusive. Therefore, the two types can be applied together, but often they are applied together by treatment professionals.

How are they attached to the image?

A while ago, I was discussing with one of my friends about the method of enhancing 3D in portraits, and I was trying to explain how to treat the images in the style of photographer Jill Greenberg. The summary of the topic is that asymmetry is best applied using the following triangle (I like to call it the contrast triangle and this is not a fixed rule, but rather from my experience only):

We observe from this triangle the steps for applying contrast and it is easy to see that the application starts with general contrast (using Curves with masks if necessary). Then we move to the stage of local variation on the important subjects in the picture. Then we reinforce the local contrast again, often with the Dodge & Burn style, on the more important logic of the previous areas. In the final stage, we sharpen where we want the viewer’s eye to focus most.

We also notice that the general contrast is wider than the local contrast, and the local contrast is wider than the local contrast enhancement, which in turn is wider than the sharpness, so why? The reason is that the wider treatment is applied in more areas of the image, and the treated areas decrease as we move to the next stage, so that we narrow our focus on the most important topic at every step. Let’s take an example (exaggerating the amounts of processing for illustration only) to understand the idea:

Main picture (friendly model Tarad Al-Qahtani during experiments in the Surprized photo session):

Image after increasing the general contrast on all parts of the image:

After increasing the contrast, we notice that the saturation has become too much, so I’ll reduce it:

Increased local contrast (face only):

Enhance local contrast (in a narrow range – on cheeks, neck, and eyes only) using paint with Light (Paint with Light or PWL):

Increased intensity (on the eyes) and may not become apparent with reduction:

Before and after (the treatment was to clarify the steps and not to obtain the best result):

We notice that whenever we moved to a step, we narrowed the scope of treatment, so we moved from the whole image to the head and then to parts of the head (cheeks, eyes, and neck), and finally we limited the treatment to the eyes only.

I hope that the topic is useful!

Firas Ghraoui