Light and contrast

Learning goal

You will be able to tidy up a photo that looks dark or flat with four basic light adjustments. You will tell apart that brightness changes the whole photo, contrast the difference between light and dark, and the shadows and highlights adjustments only a certain area; you will apply these adjustments in an order that goes from the general to the detail, explain why an area blown out to pure white can't be brought back and why opening up shadows makes grain grow, and keep the skin on faces, in every tone, with its own depth.

The question

In the late afternoon you photographed two friends sitting by the window in a café. Outside is bright, inside is dim. On the phone's screen the photo looks dark: the window is bright, while your friends' faces have turned into dark patches. Your first instinct is to push the brightness slider all the way to the right. The faces open up a little, but the window turns into a bright white void, and everything is pale and gray.

How do you rescue a dark photo? The answer isn't in a single slider, but in a few sliders used in the right order. First brightness, then contrast, then shadows and highlights. In this lesson we will talk about which part of the photo each adjustment changes, why the order matters, and past which point a photo can't be rescued.

Context

In Lesson 7.2 you cropped and straightened your photo. A bright window or an empty floor thrown out of the frame no longer misleads your light decisions. Now we move on to the second step of the workflow, light. Whichever editing app you use, the basic adjustments of this step are almost the same: brightness or exposure, contrast, shadows, highlights. In some apps whites and blacks are added to these.

These adjustments work with the photo's tonal range: the steps of tone stretching from the darkest black to the brightest white. Each adjustment shifts some or all of these steps up or down. We will see the histogram, which shows these steps as a graph, in detail in the exposure module. For now you will work with your eye: being able to look at a photo and say which area is too dark and which is too bright is this lesson's real skill.

Simple explanation

What do brightness and contrast do?

Brightness lightens or darkens the whole photo together. When you pull it to the right, the shadows, the midtones and the places that are already bright all open up together. Apps call this slider brightness / exposure under one name or the other, and it is good as a first step: it fixes a photo being too dark or too bright overall. But used alone it also opens up the bright areas, and places that are already bright, such as a window, quickly turn pure white. Set the brightness until the face or the main subject looks roughly right, and stop there.

Contrast enlarges or shrinks the difference between light and dark. When you increase it, bright places get brighter and dark places darker; the photo looks livelier and harsher. When you decrease it, the tones move closer together; the photo looks softer and flatter. After you open up the brightness, the photo often turns gray and pale; a slight increase in contrast gives it back its depth. But increasing contrast too much buries the detail in dark areas in black and the detail in light areas in white.

Why are shadows and highlights adjusted separately?

The shadows adjustment affects only the dark areas of the photo. When you pull it to the right, faces left in darkness, the corners of a room, the area under a tree open up; the bright areas stay almost in place. The highlights adjustment, on the other hand, touches only the bright areas. When you pull it to the left, the clouds in a sky, the street beyond a window, the shine on a forehead come back; the dark areas stay in place. These two adjustments solve the problem brightness alone can't: tidying up very dark and very bright areas separately when both are in the same photo.

The logic of the order comes from here. First you build the overall level with brightness, then you set the depth with contrast, and finally you bring back the detail at the ends with shadows and highlights. If you start from the other end, when you change the brightness after opening up the shadows, everything shifts again and the adjustments spoil each other. If there are whites and blacks adjustments, they are left to the very end, to set the brightest and darkest points of the photo.

What can't be rescued?

Not everything can be rescued. If an area was saved completely pure white at the shoot, there is no detail there; these are called clipped highlights. However far you pull the highlights slider, a pure white window only turns gray; the street behind it doesn't come back. In JPEG files this limit is closer; the RAW format you got to know in Lesson 3.8 leaves a little more room in bright areas, but it can't bring back a completely clipped area either.

In dark areas the problem is different. There is usually information in the shadows, but it is mixed with noise. When you open up the shadows a lot, the grain in that area grows too; a plain colored wall starts to crawl, and a night sky fills with colored dots. That is why, when opening up the shadows, zoom in on the photo, look at when the grain starts to stand out, and stop a little before it. A lesson for shooting comes out of this too: in difficult light, exposing so as not to clip the brightest and most important area is usually safer than opening up the shadows afterward.

How do you keep the tone of skin?

Light adjustments change skin directly. To open up dark skin left in darkness, using the shadows adjustment gives a better result than pushing brightness all the way; that way the face opens up while the rest of the photo doesn't blow out. But if you open up the shadows too much as well, dark skin turns gray, becoming a dull, ash-colored surface; the skin's own warmth and depth are lost. Dark skin doesn't have to be the darkest area of the photo, but it doesn't have to look like light skin either.

On light skin, on the other hand, the problem is usually in the bright areas: the light shining on the forehead, the tip of the nose and the cheekbones. Pulling the highlights down a little softens these shines and brings back the texture of the skin; but pulling them down a lot turns the skin gray and blurry. If there are two people of different tones in the same frame, look at both faces separately at the end of editing: is each close to its own color, has one been sacrificed for the other? If needed, choose a middle point that keeps both faces reasonable.

Visual evidence

Let's go back to the café photo. Two friends sitting side by side in front of the window: on the left, someone with dark skin and curly hair; on the right, someone with light skin and short hair. In the saved version both faces are dark, and the window is bright but the street behind it can still be made out. When you push the brightness all the way, the window blows out pure white, the forehead of the friend on the right turns into a white patch, and the face of the friend on the left is half opened up and grayish.

You undo the brightness and follow the order. You raise the brightness only a little; the faces become roughly visible, and the window still has detail. You raise the contrast slightly; the photo loses its paleness. You open up the shadows, and the face of the friend on the left, their eyes, their smile and the texture of their hair come out of the darkness; their skin is in its own warm brown. You pull the highlights down a little; the street and the trees beyond the window come into view, and the shine on the forehead of the friend on the right softens. You zoom in on the photo and look at the shadows; the grain is slight and doesn't stand out. The same photo; this time both faces stand in their own color and the window with its own view.

Common mistakes

Summary

The way to rescue a dark photo is to use a few adjustments in the right order: brightness builds the overall level and contrast the depth, while shadows and highlights bring back the detail only at the dark and bright ends. Clipped highlights don't come back, and opening up the shadows too much makes grain grow; on faces, opening up dark skin with the shadows adjustment in moderation and softening the shine on light skin with the highlights keeps both skins close to their own color.

Mini assignment

From the ten photos you cropped, choose at least four whose light has problems.

1. In each one, push only the brightness all the way and save the result; this is for comparison.
2. Return the same photo to its original and work in order: first brightness, then contrast, then shadows and highlights.
3. After opening up the shadows, zoom in on the photo and check whether the grain stands out.
4. In photos with people, note whether the faces look their own color; if there are two faces of different tones, look at each separately.

Check yourself

• Is the edit done in order more natural than the one done only with brightness?
• Did you notice whether you tried to rescue a clipped area?
• When you opened up the shadows, did a dark-skinned face turn gray, or did it keep its own warmth?

Glossary

Mini quiz

1. Which areas does the brightness slider affect?

• A) Only the dark areas
• B) Only the bright areas
• C) All the tones of the photo together
• D) Only the colors

2. Which adjustment is used to bring back the clouds in a sky?

• A) Pulling the highlights slider to the left
• B) Opening up the shadows
• C) Increasing the brightness
• D) Increasing the contrast all the way

3. What is the side effect of opening up the shadows a lot?

• A) The photo's colors warm up
• B) Windows blow out
• C) The horizon tilts
• D) The grain in the dark areas grows

4. Which gives a better result for opening up a dark-skinned face left in darkness?

• A) Increasing the brightness all the way
• B) Using the shadows adjustment in moderation
• C) Increasing the contrast all the way
• D) Opening up the highlights

Answers

1. C — Brightness shifts all the steps of tone together; that is why it also opens up places that are already bright.
2. A — The highlights adjustment touches only the bright areas; when it is pulled to the left the detail of the clouds comes back, while the shadows stay in place.
3. D — The information in the shadows is mixed with noise; opening up this area makes the grain grow along with it.
4. B — The shadows adjustment opens up the face without touching the bright areas; used in moderation, the skin opens up in its own color without turning gray.

Summary card

• The order: brightness, contrast, then shadows and highlights.
• Brightness opens everything; shadows only the dark, highlights only the bright.
• Clipped highlights don't come back; expose for the brightest place.
• When you open up the shadows, zoom in and look at the grain.
• Open up dark skin with the shadows in moderation; soften the shine on light skin with the highlights.

Bridge to the next lesson

You have tidied up the light; your photo is now at the right brightness. But sometimes the real problem isn't the amount of light but its color: a photo taken under an evening lamp can come out bright yellow, and one taken in shade ice blue. The next lesson shows why a photo comes out bright yellow, and how the temperature slider corrects the color tone.