Diagnostics and checking screen colors on Android

Modern smartphones are equipped with displays of the highest quality, but even the most advanced OLED and AMOLED matrices can have defects or lose settings over time. Users often notice the white balance turning yellow or the appearance of strange shades on a gray background. Checking color on Android It becomes a necessary procedure when purchasing a new device or suspecting a hardware failure.

The problem does not always lie in the screen itself; Sometimes software settings or protective films are to blame, changing the perception. In this article we will look at how to identify hidden defects, check the uniformity of the backlight and adjust color rendering without the use of expensive equipment.

There are many diagnostic methods: from built-in engineering menus to specialized applications. We will look at the most effective methods available to the average user. Test for dead pixels And checking the gradients will help you understand whether it is worth taking the gadget to a service center.

Visual diagnostics and preparation for the test

Before running any tests, you must prepare the device for testing. Clean the screen from fingerprints and dust, as dirt can imitate matrix defects. Make sure the brightness is set to maximum to identify backlight problems, but also remove any protective glass that may distort the image.

It is important to understand that the human eye is subjective. What appears to be an unnatural hue to you may be a feature of the manufacturer's calibration. Therefore visual check should be compared with a reference image or other known good device. If you notice obvious stripes, spots or dots of a different color on a plain background, this is a sign of a hardware malfunction.

For an initial assessment, upload a high-quality image with gradients. Smooth transitions from black to white and between primary colors should not have sharp jumps or “steps”. The presence of visible bands (banding) often indicates poor quality of the matrix or problems with the display driver.

⚠️ Attention: If you find static colored dots that do not change when you change the picture, these may be dead pixels. Unlike “stuck” pixels, they are difficult to recover programmatically.

Using specialized applications for Android

The easiest and most affordable way to conduct in-depth diagnostics is install the profile application from Google Play. These utilities generate pure colors across the entire screen, allowing you to identify defects that are not noticeable during normal use. Among the popular solutions are Screen Test, Display Tester and Dead Pixel Test.

After installing the application, you will be offered a set of tests. Typically the process begins by checking the primary colors: red, green and blue. When switching modes, carefully inspect every millimeter of the screen. Pay special attention to the corners of the display - this is where highlights or uneven color rendering most often appear.

• 🔴 Red channel test: checks the operation of red subpixels, often identifying dim areas.
• 🟢 Green channel test: critical for OLED matrices, where green is the main color for brightness.
• 🔵 Blue channel test: helps detect burnout or degradation of organic LEDs.
• ⚪ White and gray test: detects backlight unevenness (clouding) and color spots.

Some advanced applications offer a flicker test (PWM). This is important for users with sensitive eyes. If you see distinct stripes in front of your eyes when you shake the phone, it means the screen uses low-frequency pulse width modulation to adjust brightness.

Checking through the engineering menu and hidden codes

Many smartphone manufacturers, such as Samsung, Xiaomi or OnePlus, build hidden service menus into the firmware. They are accessed through a set of special USSD codes in the Phone application. This method does not require installing third-party software and allows you to check hardware the display at a deep level.

To enter the menu, you need to open the dialer and enter a combination specific to your brand. For example, for Samsung devices the code #0#is often used. Once entered, the command is executed automatically and a grid with test buttons appears on the screen. Find the section responsible for colors (usually labeled as Red, Green, Blue).

#0# (for Samsung)
##6484## (for Xiaomi/CIT Menu)
##3424## (for HTC and some others)

In the engineering menu, tests are launched in full screen resolution, bypassing the Android interface. This eliminates the influence of launcher software bugs. If colors are displayed correctly in this mode, but there are distortions in the normal system, the problem lies in the software or theme settings.

⚠️ Attention: Be careful in the engineering menu. Do not press buttons whose purpose you do not know (for example, Touch or Sensor) so as not to accidentally reset the sensor calibration.

What to do if the code does not work?

If standard codes do not work, the manufacturer may have blocked access to them in your firmware version. In this case, try installing the "Device Info HW" application - it can often emulate access to hidden functions or show detailed information about the matrix.

Analysis of broken and stuck pixels

One ​​of the most common problems is the appearance of defective dots on the matrix. It is important to distinguish between the concepts: dead pixel (dead pixel) is always black and does not respond to voltage, and stuck pixel (stuck pixel) lights up in one color (red, green or blue) constantly.

To identify such defects, it is necessary to cyclically run monochromatic images. A stuck pixel will glow brightly against a contrasting background. For example, a green dot will be perfectly visible against a red or blue background. A dead pixel, on the contrary, is visible as a black hole on a white background.

Defect type	Appearance	Cause	Probability of treatment
Defected (Dead) Black Point data-i="96">Sticking of the transistor in the open state	Black dot	No subpixel power supply	Low (needs replacement)
Stuck	Color Dot (RGB)	Transistor stuck open	Medium (massage or software helps)
Hot	Bright white dot	Short circuit	Low

There is a method of "massaging" the screen to treat stuck pixels, but it requires care. The idea is to apply light pressure on the defective area of ​​the switched-on device. However, modern matrices are very fragile, and inept actions can lead to the appearance of new spots or broken cables.

Adjusting color rendering and system calibration

If No hardware defects were found, but the colors seem unnatural to you, the problem can be solved by software settings. Modern versions of Android, especially shells from Samsung One UI, Xiaomi MIUI or OxygenOS, provide advanced display settings.

Go to the Settings → Display → Colors and Saturationsection. Here you will find several modes: “Saturated”, “Natural”, “Cinematic”. The “Natural” mode usually strives for the sRGB standard, providing the most accurate color reproduction, close to how the human eye sees.

For advanced users, manual calibration is available through the RGB sliders. By shifting the values ​​of the red, green and blue channels, you can remove excess tint. For example, if the screen is yellow, try reducing the red and green channels a little or adding more blue. Do this gradually, checking with a reference white sheet of paper in daylight.

• 🎨 sRGB: standard for the Internet and photographs, colors are calm and realistic.
• 🌈 DCI-P3: wide color gamut for video and cinema, colors are brighter and richer.
• 🌡️ Color temperature: adjustment from “Warm” (yellow) to “Cold” (blue).

Remember that the perception of color depends on the lighting. What seems like a perfect day may look like a cold evening. Some smartphones have an environmental sensor that automatically adjusts white balance, but this function can be disabled if it does not work correctly.

⚠️ Attention: Settings interfaces may vary depending on the Android version and smartphone model. If you don't find the RGB sliders, the manufacturer may have blocked this feature for regular users.

The influence of protective glasses and external factors

Often users make mistakes on the screen, although the problem lies in the accessories. Cheap protective glasses with a low-quality oleophobic coating or a pronounced blue filter can significantly distort the picture. They make the image cloudy, reduce contrast and add an unwanted tint.

To check the effect of the glass, try removing it (if possible without damaging it) or remember if the picture changed immediately after applying the protection sticker. It is also worth considering the factory film, which is often used to cover new smartphones. Over time, it becomes cloudy and scratched, which impairs visual perception.

External lighting plays a key role. Any screen will appear warmer under incandescent lamps, and cooler under fluorescent lamps. To objectively evaluate colors, use daylight or specialized lamps with a high color rendering index (CRI > 90).

Rainbow effect on film

If you see rainbow streaks on the screen at an angle, most likely this is the interference of light on a thick protective film or the display glass itself. This is not a matrix defect.

Frequently asked questions (FAQ)

Can a dead pixel be completely restored programmatically?

It is impossible to completely restore a truly broken (black) pixel programmatically, since this is a physical breakdown of the LED. However, “stuck” pixels that burn in one color often come to life after running special videos with a quick change of colors or lightly massaging the defect area.

Why does the screen turn yellow or pink on a white background?

This may be a consequence of the "Eye Protection" mode (blue filter) being turned on, the peculiarities of calibrating OLED matrices at low brightness (effect dirty screen) or degradation of organic layers. Try resetting the screen settings to factory settings.

Does developer mode affect colors?

Yes, in the developer menu there is a “Simulate color space” item, which can forcefully enable color blindness modes (protanomaly, deuteranomaly, etc.). Check whether this function is accidentally activated.

How to check the screen for flicker without a camera?

Without a camera, it is difficult to notice high-frequency flicker. However, you can use the Camera function in Slow Motion mode by pointing it at the screen. If dark stripes run across the screen, PWM is used. There are also light meter applications with a frequency meter.

Is it normal for the corners of the screen to be darker than the center?

For IPS matrices, slight darkening at the edges (vignetting) is acceptable, especially on large diagonals. For OLED screens, the corners must be as bright as the center. Strong darkening of the corners on an OLED may indicate a defect.