This app is designed for people who are not sure if their smartphone has a dead pixel or not. A dead pixel is a part of the display that does not work correctly. This can result from many reasons, but the main ones are:

The backlight is not coming to the screen and the screen is not properly driven.

The backlight is shining on the wrong part of the display.

The display is not being properly connected to the power source.

The power source is not providing the needed power.

There is a difference between the light emitted by the LED and the light emitted by the other parts of the display.

There is a difference between the color of the screen and the color of the pixels.

The color of the screen is changing and the colors are not showing the right values.