Dark Screen Test
Display a pure black or near-black screen to test backlight bleed, OLED uniformity, and dark room performance. On OLED displays, pure black pixels are completely off.
What to look for
Backlight bleed: bright spots or glow around the edges of the screen (LCD only).
Clouding: uneven patches of lighter areas in the center or corners.
OLED uniformity: any visible differences in darkness across the panel.
Best tested in a completely dark room for accurate results.
Testing guide
How to use the dark screen test
Pure black is where displays differ most. On OLED a black pixel is switched off entirely, while on LCD the backlight is still shining through and only being blocked. Stepping through near-black gray levels from 0 to 20 percent shows exactly how much shadow detail your panel can actually hold.
Best for
- Checking backlight bleed, clouding and IPS glow on an LCD in a dark room.
- Verifying that an OLED reaches true black rather than a very dark gray.
- Finding out at which gray level your panel stops separating shadow detail from pure black.
How to run the test
- 1Turn off the room lights and let your eyes adjust for at least a minute.
- 2Start at Pure Black fullscreen and look for any glow, patches, or light leaking in from the edges.
- 3Step up through 1%, 2%, 5%, 10% and 20% gray and note the first level you can distinguish from black.
- 4Check the corners specifically, since bleed and glow concentrate there.
How to read the result
Bright patches creeping in from the edges are backlight bleed; broad soft haze across the panel is clouding.
A silvery sheen in the corners that moves when you move your head is IPS glow, which is inherent to the technology.
If 1% and 2% gray look identical to pure black, your black level is crushing shadow detail.
Related tools and guides
Frequently asked questions
Why does my black screen look gray?
On an LCD the backlight stays on even for black pixels, and the liquid crystal layer can only block so much of it. That residual light is why LCD black looks dark gray in a dark room. OLED avoids this entirely because each pixel switches off.
What is the difference between backlight bleed and IPS glow?
Backlight bleed is light physically escaping around the panel edges and stays in the same place no matter where you sit. IPS glow is a silvery haze in the corners that shifts and fades as you change viewing angle. Bleed can be a defect; glow is normal for IPS.
How dark should a black screen be?
That depends on the panel type. OLED reaches effectively zero. A good VA panel is very dark with a contrast ratio around 3000:1 to 6000:1. IPS and TN typically sit at 800:1 to 1500:1, so black visibly lifts toward gray in a dark room.
Why use near-black gray levels instead of just pure black?
Pure black only shows light leakage. The near-black steps show whether your panel can still separate very dark shades, which is what determines how much detail you see in dark movie scenes and game environments.
Can a dark screen help save battery?
On OLED and AMOLED, yes, because black pixels are switched off and consume almost no power. On an LCD it makes no difference, since the backlight runs at the same brightness regardless of what is displayed.
Testing guide
How to use the dark screen test
Pure black is where displays differ most. On OLED a black pixel is switched off entirely, while on LCD the backlight is still shining through and only being blocked. Stepping through near-black gray levels from 0 to 20 percent shows exactly how much shadow detail your panel can actually hold.
Best for
- Checking backlight bleed, clouding and IPS glow on an LCD in a dark room.
- Verifying that an OLED reaches true black rather than a very dark gray.
- Finding out at which gray level your panel stops separating shadow detail from pure black.
How to run the test
- 1Turn off the room lights and let your eyes adjust for at least a minute.
- 2Start at Pure Black fullscreen and look for any glow, patches, or light leaking in from the edges.
- 3Step up through 1%, 2%, 5%, 10% and 20% gray and note the first level you can distinguish from black.
- 4Check the corners specifically, since bleed and glow concentrate there.
How to read the result
Bright patches creeping in from the edges are backlight bleed; broad soft haze across the panel is clouding.
A silvery sheen in the corners that moves when you move your head is IPS glow, which is inherent to the technology.
If 1% and 2% gray look identical to pure black, your black level is crushing shadow detail.
Related tools and guides
Frequently asked questions
Why does my black screen look gray?
On an LCD the backlight stays on even for black pixels, and the liquid crystal layer can only block so much of it. That residual light is why LCD black looks dark gray in a dark room. OLED avoids this entirely because each pixel switches off.
What is the difference between backlight bleed and IPS glow?
Backlight bleed is light physically escaping around the panel edges and stays in the same place no matter where you sit. IPS glow is a silvery haze in the corners that shifts and fades as you change viewing angle. Bleed can be a defect; glow is normal for IPS.
How dark should a black screen be?
That depends on the panel type. OLED reaches effectively zero. A good VA panel is very dark with a contrast ratio around 3000:1 to 6000:1. IPS and TN typically sit at 800:1 to 1500:1, so black visibly lifts toward gray in a dark room.
Why use near-black gray levels instead of just pure black?
Pure black only shows light leakage. The near-black steps show whether your panel can still separate very dark shades, which is what determines how much detail you see in dark movie scenes and game environments.
Can a dark screen help save battery?
On OLED and AMOLED, yes, because black pixels are switched off and consume almost no power. On an LCD it makes no difference, since the backlight runs at the same brightness regardless of what is displayed.