Shadow separation
Let your eyes adapt briefly, then start at the black patch and move upward. Count only visual boundaries you can see without lifting the display’s black setting during the comparison.
Can you separate nearby light and dark values?
Screen Contrast Test
This screen contrast test presents near-black steps, near-white steps, alternating blocks, a checkerboard, and subtle mid-tone detail. The patterns help you inspect visible shadow and highlight separation under current settings; they do not measure luminance or calculate a physical contrast ratio.
Read both ends before the middle
Work through the contrast test patterns
Highlight separation
Follow the bright steps toward white. Merged upper patches can reflect clipping or processing, but the screen contrast test alone cannot identify a component or numeric threshold.
Alternating extremes
Repeated dark and light blocks make spatial changes easier to spot. Local dimming, automatic brightness limiting, blooming, and panel structure may respond differently than on a full field.
Local low contrast
Mid-grey circles, line pairs, and bars test whether subtle local shapes remain visible. This pattern concerns discrimination around one tone, not the distance between black and peak white.
Avoid correcting one end at the expense of the other
A careful settings workflow
- Choose a representative environment. Reflections can hide dark detail, while a completely dark room can make edge glow or blooming seem more prominent than it is in daily use.
- Record the current mode. Note SDR or HDR state, picture preset, brightness or backlight setting, and any local contrast feature before opening the contrast test.
- Inspect shadows and highlights without adjustment. First learn what the current setup shows. If you later change a documented setting, repeat both ends rather than optimizing only the first pattern.
- Compare full-field and spatial patterns. The checkerboard and alternating blocks can trigger local processing differently from broad steps. Describe that difference instead of collapsing it into one contrast number.
- Return to familiar content. Confirm that any setting change improves useful shadow or highlight detail without washing out black, clipping white, or adding objectionable artifacts.
Observation versus measurement
What the screen contrast test tells you
| Pattern result | Visual statement you can make | Measurement still missing |
|---|---|---|
| First dark patches merge with black | Those requested shadow values are not visually separate under the tested conditions. | Black luminance, electro-optical transfer accuracy, and the cause of any crush |
| Bright steps merge near white | Those requested highlight values appear clipped or indistinguishable in this pipeline. | Peak luminance, clipping point at the signal input, and calibrated reference white |
| Checkerboard looks different from full fields | Spatial content changes the visible behavior, possibly through display processing. | ANSI contrast, sequential contrast, zone behavior, and controlled measurement geometry |
Rendering notes
How the contrast test patterns are produced
Canvas rectangles create eleven requested near-black or near-white code values. The alternating and checkerboard modes use fixed high-contrast blocks, while the low-contrast pattern places shapes a few code values above and below a mid-grey background. Rotating the step axis can make directional panel behavior easier to see.
These deterministic source values make repeat visits comparable, but output still depends on browser compositing, color management, GPU range, display tone mapping, local dimming, backlight or emissive behavior, and viewing conditions. The contrast test never converts the canvas into nits or a certified ratio.