# Setting up your Monitor

The first thing you should if you want to have a proper color management workflow is to properly callibrate your monitor. Accurate monitor calibration requires special equipment to measure your monitor's display as well as your suroundings.
However, you still obtain a decent monitor calibration if you do it manually following some simple steps. mrViewer can already help you with that.

### Geometric distortions

The first thing you should do after your monitor syncs to the new video mode is to adjust position and size of the image on the screen. You can do it either the easy way, using the monitor controls.

After the size and the position of the image are roughly set, you should check if there are any geometric distortions and get rid of them if they are present. It's often impossible to eliminate geometric distortions completely over the entire image area on older monitors, no matter how hard you try. You fix one thing and the other one goes wrong.

### Finding your monitor's gamma

One thing that is puzzling about monitors and tv sets is that they operate at a different gamma. Basically, due to voltage limitations in the early days of television (and to also target your eye's perception more accurately), monitor's screen don't display images linearly. Instead, they apply a gamma correction to anything displayed on them.
Also, by a sheer coincidence, your eyes' perception to luminance is also nonlinear and happens to also be pretty similar to the gamma correction a monitor does, so this distortion of luminance often goes unnoticed. Also, most images meant to be displayed on a tv set or monitor already take this gamma into account.
Roughly speaking, the gamma correction of your monitor is a power function.
Different monitors have different gamma settings, so you should check your monitor's specs. As a general guideline, PC monitors often use a gamma value between 2.2 and 2.5 while older Mac monitors use a gamma of 1.8. SGI monitors often use a gamma of 1.5.
Some advanced modern monitors do not operate using gamma anymore but do an internal sRGB color correction. sRGB is very similar to a 2.2 gamma function, but its curve is tiny bit different.
Scanners, Film and other input sources, on the other hand, typically have linear signal response to light intensity.
These days modern monitors have some plug-and-play capabilities that may inform your OS about its gamma settings (and other values). This information is often called EDID and perhaps some tool of your graphics card can access this information. Currently, mrViewer does not yet try to read EDID information from your monitor but your graphics card may have some utility that does. For example, under Linux and with an NVidia graphics card, nvidia-settings can often read this information for you.

If you don't know your monitor's gamma, you can try to guess it by doing a simple visual test.
Make sure mrViewer's gamma and gain are at 1.0 and that no LUT is applied.
Open mrViewer and go to the Reel Window. Then, use the RMB and select Create->Linear Gradient.
This will create a simple linear gradient going from totally black to totally white, covering your whole screen.
If you look at the values of the pixels, you will see that they change gradually from 0 to 1. You might want to maximize your window to see it properly.
If your monitor uses any type of gamma, you will see that the gradient's midpoint is not visually at the center of the screen. This is because of your monitor's gamma. Using mrViewer's gamma slider, try to adjust it until you perceive the midpoint to be at the center of the screen, like 0.45, for example.

The inverse value of that (ie. 1.0 / gamma setting of mrViewer) is roughly your monitor's gamma. Thus, if you had to set the slider to 0.45 or close-by, your monitor's gamma is probably 2.2.

### Calibrating your monitor's gain and brightness

Now that you know your monitor's gamma, to properly calibrate it, you then need to use some special image called a gamma chart. mrViewer already ships with some gamma charts for some common monitors.
Reset mrViewer's gamma and gain back to 1.0.
From the Reel Window, do RMB and select Create->Gamma Chart->2.2 (or whatever value is closer to what your monitor uses). This creates a simple gamma calibration chart for your monitor. Maximize the view so the chart covers the whole screen. You should then check that gamma chart from a distance, so that each line blends with each other. If you don't see the lines blending, you need to adjust your monitors' brightness and contrast appropriately.

### Calibrating your monitor's colors

Sadly, adjusting your monitor's color balance is much more tricky without a proper sensor.

The color balance controls of the monitor (such as color temperature or separate RGB gains) adjust relative intensities of the three phosphors, changing the overall color cast of the displayed image. Higher temperature setting corresponds to a bluer image, lower temperature - to a redder image. These controls are intended to match the white balance of the monitor to the workplace lighting conditions, i.e. make the white color displayed by monitor match the color of white paper placed next to it. It is essential for workplace lighting to be consistent. For best results, your workplace should use daylight-balanced light sources.

You might also wish to set overall color balance of your monitor at this time. Color temperature of 5400K is what the daylight is balanced at, so that's what you should set you monitor color control to. Other commonly used setting is 6500K. Some monitors default to much cooler color rendition (9000K and up).
If your workplace is next to a window, the sunlight coming from it will force you to change the color temperature of your monitor as the day goes by. In a perfect world, your monitor would come with its own sensor to the environment and adjust automatically, but sadly this is a technology not yet available.
If you are able to obtain information about the three color primaries of your monitor, you can feed this information to mrViewer in its preferences.