Problem

An issue that new photographers and graphic artists often have is that when they show their work on different displays (e.g. Laptop, TV, Picture Frame, Smartphone, printing, etc…) the image does not look the way they “remember” it while editing it on their computer. Sometimes the complaint is the image is too dark or too light, or perhaps the colors are not as vibrant. In extreme circumstances, the entire image may have an odd “tint” to it such as a haze of green or blue or some other color. It can be very frustrating, especially because when you go back to the computer you edited your picture on you find that the image looks perfect. You always want your images to look their best so it can be very upsetting to see them look odd when shown on various different displays you might have.

The Color Calibration Solution

For the most part this can be controlled with something called “Color Calibration”. Color calibration is the practice of fine tuning your displays so that they produce “true” colors. This can usually be done via various settings in your computer and display and with the use of a Calibration device such as the Data Color Spyder Pro.

Understanding How Your Display Works

Before I get into what these calibration devices do, it is important for everyone to understand the very basic idea of how your computer/tv/phone monitor works. So I will start by trying to explain that in the simplest terms I know how. I am not going to get into color “theory” because there are entire college courses to explain that. But I do have to explain a bit for everyone to understand how this color calibration works.

Display technology varies so what I am about to explain regarding RGB may not apply to your screen “Exactly”if it uses different “colors” but the fundamentals of what I am about to explain will still apply for understanding “Calibration”…. if your monitor does not use RGB, the idea of calibration would still be about adjusting color through calibration. Also, for simplicity, I will use 8-bit RGB color spectrum because it is easier to understand.

So here goes. RGB stands for Red, Green, Blue. These colors are “mixed” to produce basically any color you can think of. Your screen is comprised of thousands of Red, Green, and Blue LEDs bundled into groups of RGB “Pixels”. These groupings of LEDs are turned on in different “mixtures” to produce colors. Kind of like if you mixed Yellow and Blue paint you would produce Green paint. The principles are the same, the colors are different.

How RGB Produces Color

Let’s start with the 2 extreme ends of the colors. If all 3 RGB LEDs are in the “OFF” mode, they would produce BLACK. This is because they are not shining any light. Conversely, if all 3 RGB LEDs are turned “ON” they will produce WHITE. (I know that sounds backwards, mixing Red, Green, and Blue paint would produce an ugly color. This is “light” so it works backwards. Again not getting into Color Theory. It is not important to “understand” for this excercise anyway.).

Now lets throw 3 more basic colors the RGB LEDs can produce. If the Red LED is ON, and the Green and Blue are OFF, the color produced would be RED. DUH!. If the Red LED is OFF, Green ON, and Blue OFF…. the color produced is…. GREEN! Surprise. Finally if the Red and Green are OFF and the Blue is ON…. the color produced is?…. Thats right Blue.

So now we have shown how 3 RGB LEDs can produce 5 Colors: Red, Green, Blue, Black, and White. That’s a great start, but there are way more than 5 colors on your screen right? Well you can mix the 3 RGB colors to produce other colors. By turning them on and off in varying combinations, you can produce 16 other “mixes” of colors. Now we are really cooking we have gone from 5 to 16. Now we are getting somewhere. But 16 colors still just isn’t enough.

You can produce additional colors by adjusting the brightness of the LEDs while mixing them. Each LED can be set to 256 varying levels of brightness from 0 (OFF) to 255 (100% ON). This gives you:

Red 0-255
Green 0-255
Blue 0-255

You can explore various mixtures of RGB colors and what the mixture produces with this handy tool: http://www.rapidtables.com/web/color/RGB_Color.htm
I wont get into that any further because it is not important for this discussion.

What Does RGB Have to Do With Color Calibration?

So what does this all mean for Color Calibration? Well the “Math” behind RGB colors is a “Standard” but manufacturing of screens and displays can vary. Cheaper LEDs, screen coatings, varying resistences in electronics can cause variances in color. For example RED being set to 150 on your Laptop, may need to be set to 154 on your TV to display the “Same” shade of the color red. The further this variance is the more your colors will appear differently on different displays.

What does a Color Calibrator Do to Fix the Problem?

So what does a color calibration device do? Well you hang the device in front of your screen and the software displays colors on the screen. As this happens the device measures the brightness of the color. So for example if the software says display RED at Brightness 150, and the device reads the screen and measures the red to be at 162…. it knows that your display is off by +12 points on the RED channel. It will do these tests on all the color channels and then will record the variances across the channel such as this:

Red: Off by +12
Green: Off by -23
Blue: Off by -2

The software then takes these numbers and tells your computer to automatically adjust every color it is asked to display by those amounts. This is called a “Color Profile”. So for example since the RED channel is off by +12 that means that when the display shows RED it is 12 points too bright. So after calibration the computer will automatically reduce every request to display RED by 12 points. If it is asked to display RED 160, it will know it actually needs to display RED 148 to display “True” RED.

Your Calibration device will do this for all color channels your display can handle ths tuning your display to properly display “True” colors.

Now the trick is that you “Calibrate” all of your displays with this device so that they all display “True” colors. That way whenever you display your pictures somewhere they should always look the same.

So What Does This All Mean?

The most important device to calibrate is your computer that you edit your images on. Since you are editing them on this device it is important for it to be fine tuned. If you computer screen is uncalibrated and the RGB channels are all reducing brightness by 10% well then your image will look like it is too dark. This would cause you to try and compensate by editing your image to increase the brightness by 10%. This is because you naturally want the image to look ok on the screen you are editting it on. The problem this creates is that when you later view the image on another screen that is more acurately calibrated, or you send it to a printing company your image will be 10% too bright because you modified the image to look “correct” on your screen that is reducing the brightness.

Hopefully this all makes sense, but it sure is complex. Once again, I watered down this explanation in order to make it easier to understand. The “Science” I explained above is not the perfect exact explanation but my interpretation of it that I thought would be easy for most folks to understand. Hopefully you got something out of it.

Happy Calibrating.
Marty

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