Black Level Test
Black Level Test steps your screen through a sequence of near-black shades so you can see exactly how many dark steps your panel actually separates before everything just looks like the same flat black. Click Start Black Level Test in a dim room, cycle through the shades with the arrow keys, and note where a shade stops looking distinguishable from pure black — that point is a rough read on your display's black-level performance. The flicker test runs fullscreen so you can inspect your panel edge-to-edge under real viewing conditions.
Click Start Black Level Test in a dim room. Cycle through the near-black shades and note where a step stops looking different from pure black. Use the arrow keys or on-screen controls to move to the next pattern, and Escape to exit.
Ever wondered why shadowy game corridors look like a void of nothing, or why a tense cinematic dark scene leaves you squinting instead of immersed? Your black level test result tells you exactly how well your monitor separates near-black shades from pure black — and whether your display is silently crushing shadow detail in every game, movie, and photo you view. Getting this right means the difference between seeing a hidden enemy in a dark corner or missing them entirely.
What a Black Level Measures on Your Monitor
The term black level refers to the minimum light output a screen can produce — essentially, how dark its darkest output actually is. On an LCD monitor, absolute black is physically impossible because the fluorescent or LED light source always emits some light that leaks through the liquid crystal layer even when pixels are told to block it. An OLED, by contrast, switches individual pixels off entirely, achieving a dark output of zero nits — an inky blacks result that no LCD screen can match. Use the frame skipping test online to confirm whether your monitor shows this issue before you adjust settings or return it.
The black-level test pattern you see above presents 32 numbered near-black patches — color values 1 through 32 — arranged against a black background at RGB (0, 0, 0). Your task is simple: count how many grey squares you can distinguish from the surrounding darkness. A correctly configured monitor should render all 32 patches as visible distinct steps. When the lowest-numbered gray patches disappear into the background, your screen is exhibiting what engineers call crushed blacks — a condition where near-black values are mapped to solid black, erasing shadow depth entirely.
Why Near-Black Gradients Reveal More Than Specs
Manufacturer-quoted tonal range figures measure the ratio of peak white to minimum dark output, but they say nothing about how gracefully a unit transitions between very dark brightness steps in the near-black zone. A screen with a quoted 1000:1 differential can still perform poorly in the near-black zone if its gamma curve is misconfigured or if incorrect color range settings cause the driver to discard low-end signal values. This gradient assessment of the near-black zone exposes those failures instantly — no specialist equipment required, just your eyes and a dimly lit environment.
The test is especially valuable for gaming, where game shadows hide enemies and loot; for cinematic viewing, where a dark movie scene should reveal texture in shadows, not a flat void; and for photo editing, where lost shadow detail destroys tonal accuracy. It also surfaces issues invisible in everyday use — such as incorrect black-level mapping from a limited range graphics card signal — because most desktop content is bright enough to mask the problem.
The Difference Between Crushed Blacks and True Black
A pure dark background at RGB (0, 0, 0) is the reference floor. Every patch above it should be marginally brighter. Shadow crushing occurs when a screen maps values 1–8 (or more) to the same output level as value 0, making those dark squares invisible. This is distinct from a screen's inherent minimum-output limitation — an IPS panel with a raised floor due to light source leakage still shows all 32 patches; it just shows them against a slightly gray rather than a truly dark surround. Shadow crushing is a signal processing failure; a raised minimum output is a hardware characteristic. Knowing which problem you have determines which fix to apply.
Running the LCD Test and Reading Your Score
Before you count patches, environment matters as much as the screen itself. Run this lcd test in a dimly lit space, with overhead lights off and blinds closed. Let your eyes adjust for at least five minutes before judging results — photopic vision needs time to adapt so you can detect subtle differences among dark gray steps. Open the test in full-screen mode (or fullscreen mode via your browser's F11 key) so the browser chrome does not raise surrounding light around the pattern. Make sure your web browser or image viewer is not applying any additional color management that could alter the displayed color values. The input lag test runs fullscreen so you can inspect your panel edge-to-edge under real viewing conditions.
Brightness Targets That Actually Work for Black Level Tests
Your monitor brightness slider has a larger effect on dark-level perception than most people expect. At around 20% output, the light source level is low enough that near-black patches may vanish not because of lost shadow detail but because an output level that is brightness too low leaves insufficient tonal separation between patch 1 and the surrounding dark border. At 80% luminous output on an LCD, the raised light source lifts the minimum output floor visibly — blacks look gray and the test appears worse than it is. The practical target for this test is 50–60% on most units, which balances a realistic contrast setting with enough headroom to distinguish the lowest near-black steps. Adjust from there based on your room's ambient light.
For SDR monitor calibration, the standard recommendation is approximately 120 cd/m² (nits) for a dim environment, achieved somewhere between 30–60% on most screens. If you are running high dynamic range content, disable in-game or operating system color profile HDR mode before running the test — tone mapping reshapes the gamma curve and can make standard test patterns meaningless. After completing the dark-level assessment, restore your preferred picture mode settings.
Why 20% Brightness Can Make Blacks Look Deeper
At low output settings, the LCD light source is dimmed, so the difference between the dark surround and the near-black patches can shrink below the threshold of visibility. Paradoxically, this makes blacks appear deeper — the whole image gets darker uniformly. What you are actually observing is reduced emitted light rather than improved dark-level control. If patches 1–4 disappear at 20% but reappear at 50%, your dark floor is fine; your output level was simply set too low.
Why 80% Brightness Can Make Blacks Look Gray
High light-source output increases off-state glow — the light that leaks through closed liquid crystal cells. This raises the perceived minimum output floor, making the dark background appear charcoal gray and reducing the apparent tonal gap between patches and their surround. On an IPS panel, this effect compounds with corner luminance scatter, producing gray darks even on an otherwise healthy unit. VA screens hold a lower minimum output at high brightness due to their superior native tonal range (~3000–6000:1), so this effect is less severe — though VA smearing on rapidly changing dark content is a separate tradeoff.
Use the result interpretation table below to score your test:
| Patches Visible | Rating | Likely Cause |
|---|---|---|
| All 32 visible | Excellent — healthy black level | Display calibration is correct; gamma and RGB range are well-configured |
| Visible from 4–32 | Mild crushing | Brightness too low or gamma slightly elevated; minor adjustment needed |
| Visible from 8–32 | Moderate crushing | Wrong gamma setting, or monitor OSD Black Level set too low |
| Visible from 16+ | Severe crushing | GPU output in Limited range (16–235) feeding a full-range monitor; switch to Full RGB immediately |
Why Your Blacks May Look Wrong — Fixes From the Lagom LCD Test Tradition
The lagom lcd test pages popularized the practice of diagnosing screens with near-black gradient patterns, and their diagnostic hierarchy remains the gold standard: always start with signal chain settings before blaming the hardware. The most impactful fixes are software-level changes you can make in minutes.
Check GPU RGB Range First
The single most common cause of extreme shadow loss — patches only visible from 16+ — is a mismatch between graphics card output range and screen input expectation. When your graphics card is set to Limited range (the 16–235 range), it clips values 0–15 to black and values 236–255 to white. If your screen expects a full range (the 0–255 range) signal, the lowest 16 steps all map to identical dark output. The fix:
- Nvidia Control Panel: Navigate to Display → Change resolution → Output dynamic range → set to Full. Also confirm pixel format is set to RGB 4:4:4 Full.
- AMD display settings: Go to Display → Pixel Format → set to RGB 4:4:4 Studio (Full). Under Color, confirm full color mode is active.
- Re-run the test. If patches 1–16 are now visible, the color range was the culprit.
This also applies to television tuning via video input: check the HDMI black level or input range option in your set's picture menu and ensure it matches your source device's output. On some sets, this is labeled as limited color mode vs. standard mode.
Monitor OSD and Black Equalizer Settings
After confirming graphics card range, open your on-screen display menu and look for settings labeled Black Level, Black Boost, or Black eQualizer. These controls artificially raise the output of near-black values — useful for sport gaming visibility in shadowed scenes, but they shift the minimum output floor in ways that make pure darks appear lighter. Set this control to its neutral or standard position before running the test. Similarly, disable dynamic tonal range and adaptive output — features like content-adaptive dimming, eco dimming, or eco mode alter the light source in response to overall image brightness, which will cause the test pattern to behave unpredictably.
Adaptive Brightness and Dynamic Contrast During Testing
Dynamic light-source and adaptive dimming systems — including content-adaptive features on self-emissive and some LCD units — respond to the predominantly dark test screen by aggressively lowering peak output. This can make the near-black patches harder to see, or paradoxically easier, depending on implementation. Always disable dynamic tonal range, HDR tone mapping, and auto-dimming before running any image quality assessment or monitor calibration test. If your unit uses local zone dimming with discrete zones, switch it off entirely — zone-level behavior creates light scatter around brighter patches that distorts your count.
Backlight Leakage, IPS Glow, and Practical Room Setup
Light source bleed and corner luminance scatter are hardware characteristics, not setup failures. Corner glow, edge bleed, and corner haze are forms of backlight leakage where illumination escapes around the screen's edges. These raise the minimum output floor unevenly — a phenomenon called clouding — and can make near-black patches in affected areas harder to count. Assess dark uniformity separately with a screen uniformity test; don't confuse localized leakage with lost shadow detail across the whole image.
Room setup also matters for dark-level perception. Surrounding brightness from windows or overhead lights raises your eye's adaptation level, effectively raising the perceived minimum output floor. A matte coating diffuses reflections but adds a slight surface haze that can obscure the very darkest patches; a glossy coating creates sharper surface reflections that interact with dark content. Sit at your normal distance — viewing from an angle shifts the perceived output of near-black patches due to off-axis sensitivity, especially on IPS. Adding bias lighting behind your unit reduces the perceived gap between screen and wall, which can actually help you judge near-black patches more accurately by reducing eye strain during long assessments.
Practical checklist for accurate results:
- Set graphics card output to Full (0–255)
- Open on-screen display menu — disable Dynamic Contrast, Black Boost, Eco Mode
- Set output level to 50–60% as a starting point
- Run the test in fullscreen mode in a darkened room
- Wait five minutes for your eyes to adapt before counting
- Verify gamma is at standard target (2.2 for SDR) using a monitor gamma test
How Panel Type Shapes Your Crushed Blacks Test Outcome
No amount of tuning overcomes the physics of your panel technology. Understanding what each type can and cannot deliver in this shadow-detail test sets realistic expectations before you spend hours chasing a result your hardware cannot achieve.
OLED and Mini-LED: Stronger Blacks, More Processing
Self-emissive panels achieve absolute dark output by turning off individual pixels entirely — there is no separate light source to leak, so dark output is effectively zero. This gives these screens inky blacks and the highest practical tonal range of any current technology. However, the auto-brightness limiter (ABL) and burn-in prevention settings can interfere with the test: when the image is predominantly dark, some self-emissive units boost peak output, which shifts the relationship between patches and background. Disable auto-brightness and HDR settings before testing. Also be aware that 10-bit panels with high-dynamic-range tuning curves behave differently from SDR operation — always test in SDR with HDR disabled.
Mini-LED units use hundreds or thousands of dimming zones to approximate self-emissive-like blacks. Local zone behavior on mini-LED can produce near-zero dark output in shadowed zones, but introduces zone blooming — a halo of elevated light source output around brighter objects on dark backgrounds. During the dark-level check, a bright numbered label on a dark patch can create a glow that lightens surrounding patches, distorting your count. Test with local zone dimming off to assess base capability, then with it on to see how aggressively the algorithm interferes.
IPS: Great Angles, More Visible Glow
The standard IPS screen delivers approximately 1000:1 native tonal range, meaning the minimum output floor is already elevated compared to VA and self-emissive types. On a well-configured IPS unit, all 32 patches should still be distinguishable — they appear against a slightly gray background rather than a truly dark surround. Corner luminance scatter is most visible at off-axis positions, where the light source leaks through the liquid crystal layer at an angle. This corner glow effect can make patches in the corners appear against a brighter surround, reducing visible separation for the lowest near-black values. For low-light viewing and cinematic use, this is a persistent characteristic of IPS that cannot be tuned away — it is the inherent tradeoff for the wide viewing angle performance and sharpness that IPS delivers.
VA: Better Contrast Ratio, Different Tradeoffs
A VA screen typically delivers 3000–6000:1 native tonal range, which means its minimum output floor sits significantly lower than IPS. Against a genuinely dark background, near-black patches have better inherent separation, making them easier to see. However, VA screens exhibit dark-level smearing — a slow pixel transition time for dark-to-dark changes — which shows up as motion artifacts in fast-paced or high-refresh-rate use. VA also shows more severe dark uniformity variation with off-axis viewing: patches at the screen edges can appear lighter or darker than those at center. For static test patterns, VA usually scores well; the tradeoff appears in actual use. Refresh rate and overdrive settings affect behavior on dark content — test with overdrive at its standard setting.
6-Bit vs. 8-Bit Panels, Dithering, and Near-Black Detail
Dithering is the technique screens use to simulate color depth and bit depth beyond their hardware capability. A 6-bit driver natively produces only 64 shades per color channel. To simulate 8-bit's 256 shades, it uses frame-rate control (FRC) — also called temporal dithering — or static dithering. Understanding which algorithm your unit uses explains the noise you might see in near-black patches during this test.
Temporal dithering (or dynamic dithering) rapidly alternates between darker pixels and brighter shades on a frame-by-frame basis, creating moving patterns that average out to the target shade. If you have disabled GIF animation in your browser, you may not perceive this motion correctly. Simple temporal dithering produces visible regular patterns — a coarser noise that can be distracting in near-black zones. Advanced temporal dithering uses a more sophisticated pattern that better approximates random noise, reducing the perceptibility of the artifact.
Static dithering uses a fixed pattern of alternating lighter and darker pixels within a single frame, creating stationary patterns visible at close range. Static dithering is common on older units and many laptop display panels. A limitation of simpler dithering is that it produces only 253 shades per color component rather than the full 256 — because a 6-bit driver with 4 interpolation steps per shade yields 63×4+1 = 253 unique levels. This means units using static or simple temporal dithering are sometimes specified as having 16.2 million colors (253³) rather than 16.78 million colors (256³), and practically means the darkest three or four shades can appear identical to black regardless of your settings.
For tech enthusiasts debating color depth and bit depth — specifically 6 bit or 8 bit: what actually matters is how many of the 32 near-black steps your unit renders as visibly distinct — not the driver specification. An 8-bit driver without dithering still requires a nonlinear function to map color values to the correct target output curve, because the voltage response curve of liquid crystal pixels deviates from the target power 2.2 gamma relationship most strongly in the darker shades. A well-implemented algorithm on a 6-bit screen can outperform a poorly configured 8-bit unit in near-black rendering. The table below summarizes panel-level characteristics:
| Panel Type | Native Contrast | Black Floor Risk | IPS Glow / Bleed | Dithering Common? |
|---|---|---|---|---|
| OLED | Infinite (pixel-off) | Very Low — true black output | None (no backlight) | No (native 10-bit+) |
| Mini-LED LCD | 10,000:1+ (zoned) | Low with local dimming on; moderate off | Zone blooming risk | Zone-level dithering possible |
| VA LCD | 3,000–6,000:1 | Low natively | Minimal glow; some clouding | Yes, on 6-bit VA panels |
| IPS LCD | ~1,000:1 | Moderate — raised black floor | IPS glow at corners and angles | Yes, very common |
| TN LCD | ~1,000:1 | Moderate | Backlight bleed at edges | Yes, widely used |
Worked Examples: Diagnosing Real Black Level Test Results
IPS Monitor — Shadow Detail Restored by Fixing GPU RGB Range
A user running a mid-range IPS unit connected via video cable counts only patches visible from 16+ — every patch below 16 appears identical to the surrounding dark border. This is a textbook extreme shadow loss result. They open Nvidia Control Panel, navigate to Display → Change resolution, and find that Output dynamic range is set to Limited. Switching to Full and confirming the color format is set to 4:4:4 Full immediately changes the signal. On re-running it, patches are now visible from 8–32 — significant improvement, indicating the range fix worked. The remaining mild loss (patches 1–7 still invisible) is addressed by raising output level from 25% to 50% and running a display gamma check to confirm the tone curve sits at the standard 2.2 SDR target. Final result: all 32 visible. Image quality and sharpness across dark content are now fully restored.
OLED Monitor — Auto-Brightness Corrupting Near-Black Patches
A user on a high-end self-emissive unit runs the test and finds patches 1–8 appear fused with the dark surround — an unexpected result given the technology's reputation for inky output. The cause: the unit's auto-brightness limiter is responding to the predominantly dark test image by dimming peak output, and a secondary tonal automation feature is simultaneously mapping the near-black zone more aggressively. The user opens the on-screen display menu, disables dynamic tonal range, disables auto-brightness, and ensures high-dynamic-range processing is off. After resetting to the factory default picture mode (Standard or sRGB), all 32 patches become visible. The lesson: hardware capability is genuine, but image processing layers can override it — always strip out automation before judging your result.
Bright Room Misread — Environment, Not Hardware, Is the Problem
A user in a sunlit home office runs the test at midday and reports only patches visible from 8–32, concluding their IPS unit has a serious problem. A colleague suggests they run the test again at night with blinds closed. In a properly unlit space, after letting their eyes adjust for five minutes, patches visible from 4–32 become apparent — and after raising output from 40% to 55% and adjusting seating to their normal position, they achieve all 32 visible. Surrounding brightness from daylight and surface reflectance from a matte coating were adding enough scattered light to raise their eye's adaptation threshold, masking the lowest near-black patches entirely. The unit itself was healthy. Low-light performance of even a budget IPS can look excellent once room illumination is properly managed.
Frequently Asked Questions About Black Level Testing
What does it mean if the lowest patches are invisible?
Invisible low patches signal a dark-floor mapping failure — near-black values are being rendered as solid black. The most likely cause is a graphics card set to limited color mode (16–235 range) sending a signal to a unit expecting full color mode (0–255 range). Secondary causes include output level set too low, tone curve too high (gamma 2.4 or above compresses the near-black zone), or an on-screen display setting with Black Level set below its neutral position. Work through the checklist: graphics card range first, then on-screen menu, then tone curve, then output level.
How do I fix crushed blacks?
Follow this step-by-step workflow: (1) Set graphics card output to Full (0–255) in Nvidia Control Panel or AMD display settings. (2) Open the on-screen display menu, set Black Level to Standard/Normal, disable Dynamic Contrast and Black Equalizer. (3) Set output level to 50–60%. (4) Run a monitor gamma test — if the tone curve reads above 2.4, lower it toward the gamma 2.2 standard via the unit's tone curve menu or a custom operating system color profile. (5) Disable HDR at the operating system level if active. Re-run this tool after each step to isolate the fix.
Does lowering brightness always improve black levels?
No — and this is a common misconception. Lowering output reduces light source emission uniformly, which can hide near-black patches rather than improve them. If patches 1–4 disappear at 20% but reappear at 50%, your black level is healthy — you were simply operating below the output target needed for the test. Only raise output far enough that the 32 near-black patches become visible; exceeding 70–80% on most LCD units introduces a raised minimum output floor that creates washed-out darks.
Why does my monitor look fine during the day but glow at night?
During the day, surrounding brightness from your room raises your eye's reference level, making light leakage, corner luminance scatter, and edge glow invisible by comparison. At night, in a darkened space, your eyes adapt to a much lower ambient level and the same absolute amount of light leakage — now called lifted darks or a raised minimum output floor — becomes clearly visible. This is normal IPS and even some VA behavior. Adding bias lighting behind your unit reduces the perceptual severity by raising the ambient reference slightly, which also benefits eye strain during long gaming sessions.
Should I choose OLED, Mini-LED, IPS, or VA for the best blacks?
For the deepest darks in low-light viewing, horror games, and space scenes, self-emissive technology is the clear winner — no separate light source means zero emission on off pixels. Mini-LED is a strong second for HDR performance, offering near-zero dark depth with local zone dimming engaged, at the cost of zone blooming. VA is the best LCD choice for low-light content: native tonal range of 3000–6000:1 delivers consistently deeper darks than IPS. IPS excels at color accuracy, off-axis consistency, and response time for fast-paced gaming, but its raised minimum output floor and corner glow are inherent hardware limitations.
Is the black level test free, and does it require installation?
Yes — this is a fully browser-based display test that runs in browser with no download and no signup. It runs locally in your browser using standard web rendering; no uploads of any data occur. The entire assessment takes under a minute once your environment is set up. Your screen data never leaves your device — this is a tuning tool built for privacy and speed.
Frequently Asked Questions
- What is a black level test?
- A black level test displays a series of near-black gray patches on a pure black background. You count how many patches you can distinguish from the background. If dark patches are invisible, your monitor is 'crushing blacks' — clipping shadow detail so it all appears as pure black.
- What does it mean if the lowest-numbered patches are invisible?
- If patches 1–5 (the darkest) are invisible, your monitor has crushed blacks. This means dark shadow detail in movies, games, and photos is being clipped to pure black. You can fix this by reducing brightness, adjusting the OSD Black Level or Black eQualizer setting, or disabling aggressive dynamic contrast.
- How do I run the black level test correctly?
- For best results, test in a dark room and let your eyes adjust for at least 5 minutes. Set your monitor brightness to around 40–60%, turn off adaptive brightness or dynamic contrast, and view the screen head-on at your normal viewing distance.
- How do I fix crushed blacks on my monitor?
- First, lower your monitor brightness to around 40–50%. In your monitor's OSD menu, look for a 'Black Level', 'Shadow Boost', or 'Black eQualizer' setting and increase it slightly. Disabling 'Dynamic Contrast' or 'Smart Contrast' can also restore shadow detail. On Windows, check your GPU's color settings are set to full RGB range.
- Does panel type affect black level test results?
- Yes, significantly. OLED panels turn off individual pixels for true black, making shadow detail easiest to see. VA panels have high native contrast and generally perform well. IPS and TN panels have backlight bleed that makes blacks appear gray, which can actually make near-black patches easier to spot but indicates higher black-level luminance.
- Does lowering brightness always improve black levels?
- Not always. Lowering brightness reduces backlight output on LCDs, which can deepen blacks — but if gamma or adaptive dimming is too aggressive, it may crush shadow detail instead. The optimal brightness depends on your room lighting; match your monitor brightness to the ambient light level.
- Why do my blacks look fine during the day but glow at night?
- During the day, ambient light washes out the monitor's perceived black level, making it seem fine. At night in a dark room, your eyes are more sensitive and the backlight glow becomes obvious. This is an IPS glow or backlight bleed issue, not crushed blacks — dimming your monitor brightness will help.
- Is the black level test free?
- Yes, this black level test is completely free and runs entirely in your browser with no software to install and no account required.