Color looks fine in a bright room with the TV set to Vivid. Fill the screen with a clean solid field in the dark and you start seeing the actual panel. An edge running cooler than the center. A corner leaking light on a black scene. A gradient that steps instead of fades. You can run all of these checks in your TV’s browser in about ten minutes.
Run this the day a new TV arrives, while the return window is open. Run it on a used TV before the money changes hands.
Switch to Movie mode first
Picture mode changes how the TV processes color, contrast, and brightness. Vivid and Dynamic modes crank saturation and backlight to look striking on a showroom floor. Color tests in those modes tell you more about the processing chain than the panel underneath.
Switch to Movie, Cinema, or Filmmaker Mode before you start. Names vary by brand: Samsung calls it Movie, LG uses Cinema, Sony often defaults to a Filmmaker option. These modes skip noise reduction, sharpening, and color enhancement, so the image comes from the panel with fewer changes. Leave the sub-settings at their defaults. If you’re not sure where to start, hit reset-to-default in the picture menu and leave it there.
Open the test in the TV’s browser
Open your TV’s built-in browser and load the monitor test. Go full screen so the pattern reaches every edge with no browser chrome in the way. Dim the room before you look at anything. Backlight bleed and corner glow only show in the dark, and a bright room lets you miss both.
Step through each pattern with the arrow keys or the on-screen controls.
Solid colors: uniformity
Each solid fill should read one consistent shade across the entire screen. Check white, gray, red, green, and blue in turn.
Uniformity drift is a patch that looks slightly warmer, cooler, or dimmer than the rest. Flat gray shows it best. A patch that reads cooler or warmer than the surrounding field is obvious on a neutral, invisible on a patterned scene. Small drift at the edges of a large panel is common and stays hidden in normal content. Drift across the center or a wide band shows on bright movie scenes and can’t be ignored.
If one side reads cooler than the other, that’s uneven backlight spacing, common on edge-lit LED TVs. On an OLED it would point to pixel aging. OLED burn-in takes thousands of hours of static content. On a new set showing normal TV, it’s not the explanation.
Black screen: backlight bleed and local dimming
Put the TV on the black pattern and study the edges and corners from your normal couch distance, in a dark room.
Bright patches that hold their shape from the couch, bar-shaped or cloud-shaped, are a real defect on an LCD. A faint glow at the very corners that dims when you look straight on is IPS glow, not backlight bleed. It’s an angle effect, not a panel flaw. VA panels show almost none of either.
OLED has no backlight, so bleed doesn’t apply. A persistent bright patch on an OLED’s black screen is a pixel defect, not glow.
Full-array LED TVs split the backlight into zones and dim them individually. A bright object on a dark background blooms a halo at the zone boundary. That’s how zone dimming works, not a defect. You can shrink it by dialing the local-dimming setting down one notch in the picture menu.
Gradient: banding
The gradient pattern sweeps from light to dark. It should fade in one smooth sweep with no visible steps.
Visible steps are banding, and they mean the panel is showing fewer distinct shades than the image contains. Some banding is normal on budget TVs with 8-bit panels. Cranking contrast or color settings above default makes it worse. Banding that survives a picture-settings reset is baked into the panel’s 8-bit output. A firmware update won’t fix it.
Grid: sharpness into the corners
The grid checks whether the TV’s scaler is keeping up. Lines should be sharp and straight to the corners.
Soft or blurry lines at the edges almost always mean the browser isn’t rendering at the panel’s native resolution. Check the browser’s zoom level and the TV’s picture size setting. Most TVs call it “Picture Size” or “Screen Fit” in the picture menu. Set it to Full or 1:1.
What the results mean
Most TVs show at least one imperfection. Return the TV if bright bleed patches hold on a dark scene from your couch, or if uniformity drift covers the center of the screen. A persistent bright spot on an OLED’s black field is also a return-worthy defect.
Corner glow that shifts when you move your head, minor edge drift on a 75-inch or larger panel, and local-dimming halos are all normal. Don’t return for those.