Inspect shadow steps before changing settings
Choose Near-black shadows, sit centered, and allow your eyes a moment to adapt to the room. The background is RGB 0. Each rectangle uses the same code in its red, green, and blue channels: 0, 2, 4, 8, 12, 16, 24, or 32. The zero rectangle intentionally matches the background. Look for a gradual increase in visibility toward the brighter codes, rather than expecting every tiny step to be obvious under every condition.
Use fullscreen and hide labels when their bright text interferes with a subtle judgment. Restore labels afterward to identify which rectangles you saw. Keep normal display brightness and room lighting as a starting point. Reflections can make low steps harder to distinguish, so eliminate a bright reflected window before compensating with monitor controls. Leave the browser image unchanged while comparing a display setting, and write down the original setting so you can return to it.
Check highlights and clipping separately
Switch to Near-white highlights. The background is RGB 255 and the rectangles run from 223 through 255. The final white rectangle intentionally blends into the white background. Look for distinctions among the other patches, especially the brighter end. These are encoded image values; equal numeric differences do not imply equal differences in visible luminance. Your display transfer function and rendering path influence the appearance.
If multiple near-white patches merge, investigate the monitor's contrast control, image processing, system HDR mode, and the connection's signal-range settings. If several shadows merge, investigate black-level or range settings and ambient light. Do not change a signal range blindly: source and display expectations must agree. A limited/full mismatch can crush shadows and highlights or make blacks look gray. Consult the device documentation for the correct configuration instead of forcing a setting because one browser image looks different.
Understand what the result can tell you
This page is a visual clipping and distinguishability check, not a contrast-ratio meter. Contrast ratio requires measuring emitted luminance in defined black and white conditions. It also depends on local dimming, measurement geometry, and display behavior; the RGB numbers cannot replace that measurement. Seeing a particular near-black step does not prove accurate gamma, and failing to see code 2 in a bright room does not by itself establish a defect.
Compare the same pattern in SDR and HDR only if you intentionally want to examine those rendering modes, and record which mode is active. A web pattern can be transformed by the operating system or browser. It is not an HDR calibration target or a standardized video-range test. Night modes and color filters can further change the image. If normal photographs show lost shadow detail as well, use consistent examples when asking the manufacturer for help.
After checking steps, inspect a familiar photograph with dark textures and bright detail. A setting that makes every tiny shadow patch visible may wash out normal content. Balance practical detail with your usual room lighting, and return to a supported display preset if adjustments become confusing. The uniformity test can reveal spatial patches that interfere with a step comparison; the color-and-pixel test provides solid fields for a different inspection task.
Example: lost shadow detail versus gray-looking black
Suppose several neighboring near-black rectangles blend into the background while a familiar dark photograph also loses texture. This suggests checking the shadow rendering path, rather than raising brightness until every coded step appears. Compare one documented black-level or signal-range setting at a time, keeping source and display range expectations matched. The deliberately matching RGB 0 rectangle should still blend into its background.
A different case is a black background that looks gray while the brighter patches remain easy to distinguish. Reflections, panel black level, or a signal-range mismatch may contribute, so this is not automatically the same problem as clipped shadows. Check the room reflection and the documented source/display configuration before adjusting controls. Neither appearance supplies the luminance readings needed for a contrast ratio.
Frequently asked questions
Is this a measured contrast ratio?
No. The test uses digital RGB values for a visual comparison. Contrast ratio requires luminance measurements under specified conditions, so the page cannot output a reliable ratio.
Should I see the RGB 0 rectangle?
No. It matches the black background deliberately. The RGB 255 rectangle also matches the white background in highlight mode; these endpoints give a reference for the neighboring coded patches.
Must every near-black rectangle be visible?
No universal visibility threshold applies here. Room light, brightness, display processing, viewing position, and adaptation affect tiny steps. Judge normal content as well as the pattern.
What can cause crushed blacks?
Ambient light, image processing, or a mismatched signal range can hide shadow detail. Check documented source and monitor settings one at a time before concluding the panel is faulty.
Can I calibrate HDR with these steps?
No. The page is not a standardized HDR target and does not measure luminance. The operating system may transform the image in HDR mode; use your platform and display calibration guidance.