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Blue Light - What’s the Problem? Human eyes have receptors that contain a photopigment called melanopsin that is sensitive to blue light; blue light is known to be phototoxic for the retina.2 Blue light penetrates all the way to the retina (the inner lining of the back of the eye). Too much exposure to blue light can damage light-sensitive cells in the retina. This causes changes that resemble those of macular degeneration, which can lead to permanent vision loss. Blue light is defined as a high-energy visible (HEV) light that ranges between 380 and 500 nm. HEV is a short wavelength that produces a higher amount of energy. When you look at a computer screen, the blue light enters your eyes and signals the pineal gland to suppress the secretion of the hormone melatonin. Melatonin is a sleep hormone that helps to regulate your circadian rhythm. So, excessive blue light exposure doesn't sound like a healthy proposition, but that is what we are dealing with. More people are working remotely, which often means a shorter commute to the home office (couch), and longer hours spent looking at a bright screen emanating biorhythm-disrupting blue light. What do we do about that catch 22? Well, there are creative geniuses working on solutions. Use a Blue Light Filter on Your Computer Screen To prevent health problems and non-restorative sleep cycles, developers have created programs that adjust the screen colour to filter out the faster wavelengths we call blue light. These programs are called (surprise!) blue light filters. Across different platforms, users have numerous blue light filters to choose from. Some may prefer one from another for various reasons. When it comes to Ubuntu, the most common choices are Redshift and F.lux. However, some users have had issues with these programs and are in search of alternatives. We will cover some decent options you should consider when searching for the perfect blue light filter for you. Some operating systems (Windows, MAC) started to incorporate their versions of blue light filters. However, third-party programs provide more advanced features over the built-in blue light filter applications. Open Source Alternatives to F.lux F.lux is considered to be one of the most popular blue light filters. You can find F.lux on many different platforms, such as Windows, MAC, and Linux. The program has always had a simple and pleasant interface, which was appealing to users from the start. Simple to Use, But Not Open Source F.lux is pretty simple to use. You enter your latitude and longitude information, zip code (US users only), and the nighttime colour temperature. Users usually go for Halogen (3400K). After this, your application is set, and you can continue with your work. Throughout the years, some users had issues with the program, which led to the inevitable. Many started to look for alternatives. Also, F.Lux is considered to be a closed source program (which means you can’t edit the source code). Many users prefer to use open-source alternatives in order to change the source code as they desire. There are various open-source blue light filter programs for Ubuntu, and we will cover some of the most popular choices users usually go for. Gammy F.lux reduces the screen’s blue light and displays warmer colours at night. However, some applications are also overly bright during the day. In this situation, night mode isn’t the best solution. Gammy is an open-source blue light filter that will help you in this situation. The application allows adaptive brightness. This will make bright-screen content easy on the eyes, without having to run night mode. Gammy does this by taking a screenshot after a certain period and then slowly adjusts the brightness based on the screenshot. Once you have started the app, the interface will show up. In it, you will find several sliders that will help you adjust your screen colour to a satisfying degree. The minimum and maximum brightness levels can be adjusted manually and automatically. Another significant option this program has is offset. A higher offset percentage means the brightness of the screen will be higher. The temperature setting will allow you to define the colour temperature levels. This option is common with other screen dimming applications, such as F.lux. If you want the application to set the colour temperature levels for you, click on the three dots in the top right corner. This will open a Temperature schedule form. Here you will be able to set the start and end time. It’s important to notice that the maximum temperature is 6500K, and the lowest is 2000K. Gammy has a couple of other options for those who like to go into detail. To access these options, click and drag the bottom right corner of the form. After this, an additional three settings will pop up under the standard ones. The extra options you will get are adaption speed, threshold, and screenshot rate. Calise Calise is another open-source program that reduces blue light emissions on your screen. However, it is unique in its own way. Calise uses a web camera to detect the room’s lighting, and with that information, adjusts the screen brightness. This program also has additional unique features. When you start the program, you will notice a command line, GUI (tray icon included) interface with a daemon mode. Calise also supports different profiles. This means that you can store specific configurations on various profiles. Switching threw profiles is relatively easy. Just enter cli switch “-profile” in the command line. The program automatically recognizes dawn and sunset and uses weather information based on the latitude and longitude information. DBus service is optimized. All of the calculated information can be exported as a CSV file. If you are interested in this, you’ll have to enable recording. After this, every session the program has recorded will be exported. Brightness Controller This is another free and open-source Linux application. It’s specific because it allows you to control your primary and secondary display’s brightness using a GUI. It has two main features: the first one is brightness control, and the second one is saving colour profiles. Just like Calise, this program is also written in the Python language. Once you start the program, a dialog box will show up. In it, you will find settings for both your primary and secondary monitors. The features are the same for both. For each monitor, you will have four sliders, one for brightness, and the other three for adjusting the colour temperature by changing the RGB values. Suppose you are interested in advanced features. The brightness controller also includes primary brightness, secondary brightness, and colour temperature. In case you have four monitors, you can use the Brightness Controller Simple. However, it doesn’t have a colour temperature setting (RGB). Desktop Dimmer Another popular choice when it comes to open-source blue light filters is Desktop Dimmer. The developers state that the app can enable dimming darker than dark for both your internal and external screens. This app was developed to help people struggling with insomnia. The app doesn’t offer many fancy features like some other blue light filter apps. However, that is precisely what the developers intended. An app that will help users adjust both internal and external monitors’ brightness and do that quickly and easily. Desktop Dimmer is easy to use. As soon as you start the program, a pop-up menu will show up. On it, you will find only one slider, which is used to set brightness: 0% being full brightness and 100% no brightness at all. This app can be used on multiple monitors and lets you adjust the brightness for each monitor separately. Blueshift This eye care application was inspired directly by Redshift. It automatically sets your monitor colour temperature and brightness to help you focus on your work. Blueshift also prevents insomnia and improves the quality of your sleep. However, it’s not considered to be a user-friendly app. The app has a couple of unique features, the first one being the ability to cancel out effects of sigmoid curves. The app supports curve operations over linear RGB and CIE. This can be useful for more accurate brightness modifications. If, for any reason, Blueshift doesn’t work for you, take a look at Redshift. We will further explain the Redshift in the following section. Preloaded Ubuntu Software (Redshift) - The Winner Together with F.lux, Redshift is considered to be the most popular choice for users when searching for a blue light filter. The main difference between these two programs is that Redshift is a command-line program. This may seem intimidating for some, and others don’t mind this and find it relatively simple to use. Also, if you are running low on RAM memory, Redshift is the way to go. The program uses a tenth of the memory F.lux uses. This is mainly because of the simplicity of the program. Redshift adjusts your screen colour temperature depending on the position of the sun. This means that your screen colour temperature will be set differently during the night and daytime. Throughout the night, the colour temperature will transition slowly from night to daytime. This allows your eyes to adapt quickly to different lighting settings. When you first start the app, you should experiment with the colour temperature and brightness in order to find the ideal settings for yourself. Once you’ve done that, you will have to determine your geographical location. Redshift can use your system’s built-in location provider. Which means you don’t have to worry about inserting latitude and longitude details. After this, you can configure Redshift to change colours individually and reduce brightness differently. The balance between the brightness and colour temperature makes the screen easy to watch and rests your eyes. At first, Redshift only had a command-line interface. However, now it also has a graphical user interface (GUIs) that are supported by most Linux desktop environments. Redshift is preloaded in Linux Mint.