Question 1

How do I test for dead pixels?

Accepted Answer

Start the colour test and step through red, green, blue, white, black and grey full-screen. Look closely for any dot that stays the wrong colour. A pixel that is always black on a white background is dead; one that glows on a black background is stuck.

Question 2

What is the difference between a dead pixel and a stuck pixel?

Accepted Answer

A dead pixel receives no power and stays black on every colour. A stuck pixel is permanently lit in one colour, so it shows up most clearly on a black screen. Stuck pixels sometimes recover on their own or with rapid colour cycling; dead pixels essentially never do.

Question 3

Can this test fix a stuck pixel?

Accepted Answer

Sometimes. Rapidly cycling colours over a stuck pixel for 10 to 20 minutes can occasionally unstick it. It is not guaranteed and it will not help a truly dead pixel.

Question 4

How do I test if my touchscreen has dead zones?

Accepted Answer

Use the touch test and drag your finger slowly across the whole screen in overlapping lines, including right to the edges. Any gap in the trace where your finger was down is an unresponsive area. Remove a thick case or screen protector and try again before concluding the digitiser is faulty.

Question 5

Why does the test not go truly full screen on iPhone?

Accepted Answer

Safari on iOS does not grant the Fullscreen API to web pages, so the overlay fills the viewport but the browser chrome may remain. Scroll down once to hide the address bar, or use the mobile app for a genuine full-screen test.

Dead Pixel & Touch Screen Test

1. Dead pixel test

2. Touch test

What each colour reveals

Frequently asked questions