Monitor calibration

Learning goal

You will be able to explain why the colors and tones you see while editing a photo on screen come out differently in print, and adjust your screen to reduce this difference. You will understand the basic difference between a screen that emits light and paper that reflects it, and see why a screen being too bright leads to prints always coming out dark. You will get to know the three basic values set when adjusting a screen, brightness, white point and gamma, and know why they should be set with a measuring device rather than by eye. You will arrange the light around the screen and the light used when looking at a print, and learn how often calibration needs to be renewed. You will tell how a bright, uncalibrated screen misleadingly shows the shadow detail of dark skin in a way that will be lost in print, and how it can make you correct light skin in the wrong direction.

The question

The baker wants to hang on the shop's wall the photo in which they hand bread to their elderly neighbor. Your friend from the club edits the file one last time on their laptop; on screen the frame is warm and bright, the baker's dark skin glows, fine details can be made out even on their shaded cheek. They send the file to a print shop.

The print that comes back is completely different. The whole frame is clearly darker; the neighbor's white headscarf has turned a dirty gray, the whole frame leans toward red, and the shaded half of the baker's face has closed into a pitch-black mass. They object to the print shop; the print shop says they printed the file as it was, and that the problem may be in the screen. Why is the color on my screen different in print? Which is right: the screen or the paper?

Context

We mentioned while working through color profiles that the screen, too, is a tool that needs adjusting, but we didn't go into how to do it (Lesson 11.9). In the white balance lesson, too, we discussed why a neutral reference, a gray card, is indispensable in judging color (Lesson 11.2). This module carries the photo from screen to wall, and its first stop is the screen itself, where all editing decisions are made.

The fourth level is for those who want to turn their photography into their own work and their own style. A photographer's work often ends with a print, an exhibition or a client's wall. Every decision made on screen can be carried to print only if the screen shows things correctly.

Simple explanation

Why do the screen and paper look different?

A screen emits light; a print, on the other hand, reflects the light that falls on it. This basic difference is why the two never look exactly the same. A screen's brightest white is a backlit light source and brighter than almost everything else in the room. Paper's brightest white, on the other hand, is only the paper's own color and is limited by how much of the room's light it reflects back. Paper's darkest black is also limited by how much light the ink swallows; it can't be as deep as a screen's darkness.

Display luminance is the value that states how bright a screen shows a white area, measured in candelas per square meter. Laptops and phones are often set very bright so they can be read in daylight. A photo edited on such a bright screen looks brighter than it really is; the photographer leaves it as it is, or darkens it even more, instead of brightening it, and the print comes out dark. For a screen that will be compared with prints, the common suggestion is to bring the brightness down to between about eighty and a hundred twenty candelas per square meter; the exact value is chosen according to the room's light.

What is adjusted in calibration?

Display white point is the value that decides at what color temperature a screen shows white. Most screens, as they come out of the box, show a cool, bluish white. A photographer editing on a bluish screen warms the photo without noticing; the print, on the other hand, comes out on paper's neutral white and looks too warm, reddish. The common target for photo editing is a white close to daylight, about 6500 kelvin.

Gamma is the value that decides with what curve a screen shows tones from dark to light, that is, how dark or light the midtones will look. When gamma isn't set correctly, the shadows look lighter or darker than they are and the photographer corrects the shadows in the wrong direction. The common target is a gamma of 2.2.

A colorimeter is a small device placed in front of the screen that measures the colors and brightness the screen shows and creates a profile for the screen based on this measurement. Calibration is done with a device because the eye constantly adapts itself to its surroundings: an eye that looks at a bluish screen for a few minutes starts to count it as white. Adjustments made by eye can be a starting point, but they don't replace a reliable measurement. During calibration the program shows a series of colors on the screen, the device measures them, and the computer saves a profile that brings the screen to the target brightness, white point and gamma. Because screens change over time, renewing calibration every few weeks is a common habit.

For calibration to work, the screen's own automatic settings also need to be turned off. The feature that changes brightness by itself according to the ambient light, the night mode that turns the screen yellow in the evenings, and preset display modes that liven up colors, unnoticeably break the balance set by calibration. Turning these features off while editing makes sure the screen shows things the same way every time it is switched on.

What do the room and skin change?

Viewing light is the light close to daylight, showing color faithfully, under which a print is looked at when deciding its colors and tones. A print looked at under a warm household lamp shifts to orange, and under a fluorescent tube to green. When comparing the print with the screen, neutral and bright enough light makes sure the two images are placed side by side fairly. The light around the screen matters too: bright light coming from a window behind it, or a lamp hitting the screen, makes the eye perceive the screen differently than it is. Editing in dim, steady light makes sure decisions are made under the same conditions every day.

An uncalibrated, overly bright screen misleads most on skin. A bright screen shows the fine details in the shaded areas of dark skin; the photographer finds these details sufficient. But in print the same shadows close up at the limit of paper and ink, and half of the face can turn into a pitch-black mass. On a calibrated, dimmer screen this closing up is seen before printing, and the detail in the shadows is recovered carefully only in that area, without lightening the whole face; the goal isn't to show the skin lighter than it is, but for the detail to reach the paper. A bluish screen, on the other hand, shows light skin as pale and pushes the photographer to warm it; in print the same skin shifts to a pink, flushed color.

Visual evidence

You calibrate your laptop's screen with a colorimeter. You choose the targets as about a hundred candelas of brightness, a white close to daylight and a gamma of 2.2. When calibration is finished, the screen looks clearly dimmer and a little warmer; at first it feels dull.

Opening the same file with the new profile, you see how dark the photo really is. The neighbor's white headscarf leans slightly toward gray, the whole frame has shifted toward red; there is almost no detail to be made out in the shaded half of the baker's face. You neutralize the headscarf against a gray card, lighten the whole frame a little, and gradually lighten the shadow area of the baker's face with a separate mask, preserving the warm brown of their skin.

When you put the new print next to the screen under a lamp close to daylight, the two come very close to each other. In the shadow of the cheek that had closed up in the first print, fine lines can now be made out, the headscarf is a clean white, and the baker's skin is the same deep, warm brown as on screen. They aren't exactly the same; the screen is still a little brighter and livelier, but the difference is now predictable.

Common mistakes

Summary

A screen emits light and a print reflects it; that is why the two never look exactly the same, but an overly bright, uncalibrated screen widens the difference and leads to prints coming out dark or with shifted colors. Calibration brings display luminance, the display white point and gamma to known targets with a colorimeter, and is renewed regularly; editing is done in dim, steady light, and the print is compared under a viewing light close to daylight. A bright screen shows the shadow detail of dark skin in a way that will be lost in print, and a bluish screen makes you warm light skin too much; on a calibrated screen, detail is recovered without showing skin lighter than it is.

Mini assignment

In this assignment you will test how well your screen matches print.

1. Note your screen's brightness setting and whether its white looks warm or cool; if you have a colorimeter, calibrate the screen, and if not, bring the brightness down clearly and look for a place where you can get a calibration done.
2. Have a photo printed as a small print that contains both light and dark tones, a white surface and if possible a human face.
3. Put the print next to the screen under light close to daylight; write down the differences in brightness, color and shadow detail.
4. If there is a person in the photo, check whether the detail in the shaded area of their face survived in print; if it didn't, correct that area without lightening the skin and print again.

Check yourself

• Can you explain the consequence of the difference between a screen emitting light and a print reflecting it?
• Can you name the three values adjusted in calibration and why a measuring device is needed?
• Were you able to check whether a face's shadow detail survived in print, and correct it without lightening the skin?

Glossary

Mini quiz

1. Why does the print of a photo edited on a very bright laptop screen come out dark?

• A) Because the printer ran out of ink
• B) Because the file is small
• C) Because the bright screen shows the photo brighter than it is and the photographer doesn't brighten it
• D) Because the paper is too glossy

2. How does the print of a photo edited on a screen showing a bluish white look?

• A) Too warm, reddish
• B) Too blue
• C) Black and white
• D) Exactly the same

3. Why is calibration done with a measuring device rather than by eye?

• A) The device brightens the screen
• B) The eye can't see colors at all
• C) The device corrects the print
• D) The eye adapts to its surroundings and over time counts a bluish white as white

4. On the bright screen, detail can be made out on the dark-skinned baker's shaded cheek, but in print half of the face is pitch black. What is the most correct fix?

• A) Lightening the whole photo by two stops
• B) On a calibrated screen, gradually lightening the shadow area with a separate mask, without showing the skin lighter than it is
• C) Turning the photo into black and white
• D) Printing on glossier paper

Answers

1. C — A bright screen shows tones lighter than they are; the print carries the real tones and so comes out dark.
2. A — The photographer warms the photo to balance the bluish screen; the print looks too warm on neutral paper.
3. D — Because the eye adapts, it hides the screen's error; the device takes an absolute measurement.
4. B — The goal isn't to lighten the skin but to bring the detail in the shadow to the paper; a local, gradual correction does this.

Summary card

• The screen emits light, the print reflects it; they are never exactly the same.
• Bright screen = dark print; lower the brightness.
• Calibrate: brightness, white point, gamma; with a colorimeter and regularly.
• Edit in dim, steady light, compare the print under light close to daylight.
• On dark skin, check shadow detail against the print; recover it without lightening the skin.

Bridge to the next lesson

Once the screen was calibrated, the print began to match the screen. But when the baker wanted to see the photo on their phone, a new oddity came up: on the phone the reds were almost fluorescent, on the computer measured, and in the copy uploaded to the bakery's web page, faded and dull. The same file was like three different photos on three different devices. Why do colors change from device to device? The next lesson deals with color management, which explains color spaces, color profiles and converting a file between devices.