Black Crush Test: Check Monitor Shadow Detail and Fix Crushed Blacks

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Dark scenes should still have detail.

If caves, night scenes, dark clothing, hair, and horror-game corners all collapse into one flat black shape, your monitor may be crushing blacks.

I published the full source-backed version on KeyboardTester.click with the live test, FAQ schema, localized versions, images, source notes, and related monitor tools:

This DEV.to version keeps the practical diagnostic and fix workflow.

Fast answer

Run a black level test in a dim room and look for the first near-black box you can separate from the background.

If boxes 1-5 disappear but 6-8 are visible, you have mild black crush.
If the first visible box is 9-15, tune brightness, HDMI black level, RGB range, and gamma.
If only 16+ is visible, suspect a severe Full vs Limited RGB mismatch or an aggressive OLED/HDR shadow setting.

The lowest boxes should be barely visible, not bright. You are looking for separation from the background, not a gray-looking screen.

What black crush means

Black crush is when near-black tones are clipped into pure black.

Instead of seeing separate shadow steps, the display makes many dark values look identical. That hides texture in:

night scenes
horror games
dark clothing
hair and skin shadows
caves and interiors
OLED HDR content

This is different from washed-out blacks. Black crush hides detail by making shadows too dark. Washed-out blacks lift the black floor so black looks gray.

Run the test properly

Use one controlled test before changing a dozen settings.

Open the Black Level Test.
Let your eyes adapt for 30-60 seconds.
Use your normal input, monitor mode, and brightness.
Turn off dynamic contrast and extreme black stabilizer modes for the first pass.
Count the lowest numbered patch that separates from the background.

Change one setting, then run the same test again.

That discipline matters. Otherwise you can mistake RGB range, gamma, HDR, and game sliders for the same problem.

How to read the result

First visible box	Meaning	Next action
1-3	Excellent shadow detail, or brightness may be slightly high	Compare with a color range test
4-5	Normal to mild crush	Usually fine if dark scenes still show texture
6-8	Mild black crush	Raise brightness slightly and check gamma
9-15	Moderate crush	Check HDMI black level and GPU RGB range
16+	Severe crush or range mismatch	Reset picture mode and match Full/Limited range

If black becomes gray while trying to reveal the first patches, stop. You may be fixing the wrong problem.

Fix path for crushed blacks

1. Brightness / black level

Raise brightness until patch 2 or 3 barely separates from black, then stop.

If the whole black floor becomes gray, brightness is too high or RGB range is wrong.

2. HDMI black level

Monitor menus use names like:

Black Level
HDMI Black Level
Input Range
RGB Range
Low / Normal
Limited / Full

The exact label varies by brand. The important part is matching the display expectation with the GPU output.

3. GPU output range

For most PC monitors, Full RGB 0-255 is the right output.

Limited range, 16-235, is common in TV/video chains. It is not automatically wrong, but a mismatch causes problems:

GPU output	Display expectation	Result
Full 0-255	Full 0-255	Correct for most PC monitors
Limited 16-235	Limited 16-235	Correct for many TV/video chains
Limited 16-235	Full 0-255	Washed-out gray blacks
Full 0-255	Limited 16-235	Crushed shadow detail

If your blacks are crushed, that fourth row is a common cause.

4. Gamma

High gamma darkens midtones and shadows. Low gamma reveals detail but can make the picture flat.

Use a monitor gamma test after RGB range is correct.

5. HDR and game sliders

Calibrate SDR first.

Then set HDR black point and in-game brightness using the game instruction: the logo should be barely visible, not comfortably bright.

OLED and HDR notes

OLED panels make black crush easier to notice because true black is extremely deep. The jump from black to the first visible step can be abrupt.

HDR tone mapping, VRR behavior, and black stabilizer features can also change near-black detail.

If only one area of the screen loses shadow detail, also run a screen uniformity test. If the whole screen clips evenly, settings are more likely than a panel defect.