Contrast Test
Check that shadow and highlight detail survive on your screen.
Every step should be distinguishable from its neighbours, including the darkest against pure black. Steps that merge mean black crush: shadow detail is being thrown away, usually by the brightness or contrast setting, or by a black level set to Low on a TV. Do this in a dim room — ambient light hides the dark end completely.
Your test runs locally in your browser. No device data is uploaded.
How to use the contrast test
Look at the near-black strip in a dim room and count how many steps you can distinguish from the background and from each other. Then switch to near-white and do the same. Every step should be visible as a separate shade.
Black crush and clipped highlights
Steps merging into black at the dark end is black crush: shadow detail is being thrown away before it reaches your eyes, so night scenes turn into flat dark shapes. Brightness set too low, contrast set too high, or a black level set to Low on a TV input are the usual causes.
Steps merging into white is the same problem at the other end, where highlight detail disappears into a flat white. Contrast set too high is the common cause, along with punchy presets like Vivid or Dynamic.
Why the room matters
Ambient light reflecting off the panel raises the effective black level and hides the dark steps completely, so a test done in a bright room will always look like black crush. Judge the dark end in a dim room, which is also the situation where black crush actually bothers you.
The two ends often trade against each other. Pushing contrast up to recover highlight punch tends to crush shadows, so it is worth checking both strips after any adjustment rather than tuning one in isolation.
Frequently asked questions
- What is black crush?
- Dark shades merging into pure black, so shadow detail simply disappears. On the near-black strip it looks like the first few steps being indistinguishable from the background. Brightness set too low, contrast too high, or a black level set to Low on a TV input are the usual causes.
- What if the near-white steps merge?
- That is clipped highlights, the same problem at the other end. Contrast set too high is the most common cause, along with punchy picture presets like Vivid or Dynamic.
- Why does it look different in a bright room?
- Ambient light reflecting off the panel raises the effective black level and hides the dark steps entirely. Judge the near-black strip in a dim room, which is also where black crush actually bothers you.