Monitor Uniformity Test

Introduction

The DeviceHub Monitor Uniformity Test is a free online flat-field inspector that paints even gray (and related) screens so you can visually assess brightness and color uniformity, clouding, bleed, and tint patches, without a multi-zone laboratory camera. Monitor buyers checking IPS glow, OLED owners hunting dirty screen effect, reviewers photographing edge bleed, and offices rejecting blotchy conference panels use full-bleed gray because uneven backlight and coating issues pop against a flat tone. Open the page, go fullscreen in a dark room, and scan corners and center. DeviceHub relies on visual judgment; it does not claim automated AI heatmaps of every defective zone or ISO uniformity certificates. Pair with Gradient Test for banding versus blotch distinction, Color Test for tinted solids, Dead Pixel Test for discrete cells, and Black Level Test for near-black clouding. Clouding, backlight bleed, and dirty-screen texture rarely show up in a busy desktop wallpaper, but a flat gray field makes uneven luminance and tint patches impossible to ignore. DeviceHub’s Monitor Uniformity Test paints even gray (and related) screens so you can visually assess brightness and color uniformity without a multi-zone laboratory camera or automated AI heatmaps of every defective zone. Monitor buyers checking IPS glow, OLED owners hunting dirty-screen effect, reviewers photographing edge bleed, and offices rejecting blotchy conference panels use full-bleed gray because uneven backlight and coating issues pop against a flat tone. Honesty stays intact: judgment is visual; DeviceHub does not issue ISO uniformity certificates or claim machine-vision zone grading. Pair with Gradient Test to separate banding rings from blotches, Color Test for tinted solids, Dead and Dead Pixel Tests for discrete cells, Black Level Test for near-black clouding, and Contrast Test when the whole image is milky rather than locally blotchy. Permissions remain none so return-window checks work on any browserable PC. Return-window photography for backlight bleed works best after a dark-room gray pass you actually viewed on-axis; DeviceHub supplies the flat field while you supply patient eyes and honest notes. Offices rejecting conference panels can require a medium-gray scan before accepting delivery, catching clouding that slides and charts hide. OLED dirty-screen effect and LCD bleed are different beasts, describe texture versus edge glow rather than using one vague “uneven” word. Clean the glass first every time; forehead oils on laptops create repeating blotches that move when wiped and do not deserve RMA language. Pair with Black Level Test when clouding appears only near black, and with Gradient Test when the artifact is concentric banding instead of blotches. Dead Pixel Test remains available if a “blotch” collapses to a single fixed cell under colored fields. No AI zone map will appear, browsers cannot honestly promise one, so do not demand a heatmap screenshot from this page. Permissions stay none; local inspection beats remote codecs that invent false clouds.

What this tool does

Flat gray levels at different percentages help separate bleed (bright edges on dark gray) from dirty-screen texture. Guidance covers on-axis viewing and cleaning the panel first. The tool does not adjust local dimming zones. It does not upload uniformity photos. Angle the display only after an on-axis pass so IPS glow is not mistaken for broken zones. Flat gray levels at different percentages help separate bleed (bright edges on dark gray) from dirty-screen texture across the center. Guidance covers on-axis viewing, cleaning the panel first, and not judging IPS glow solely from extreme angles. The tool does not adjust local dimming zones or upload uniformity photos. Angle the display only after an on-axis pass so normal glow is not mistaken for broken zones. OLED ABL can subtly reshape large gray fields over time, note timing when comparing two units. Stepping between gray percentages often reveals bleed that is invisible on 50% gray yet obvious on 5–20% gray, exercise more than one level.

When to use it

Use Uniformity Test during return windows, after panel replacements, when gray UI looks stained, and when comparing two units side by side. Prefer Dead/Stuck pixel tools for single dots. Prefer Gradient for contour rings. Prefer Contrast when the whole image is milky rather than blotchy. Use Uniformity Test during return windows, after panel replacements, when gray UI looks stained, and when comparing two units side by side under matched brightness. Prefer pixel tools for single dots; prefer Gradient for contour rings; prefer Contrast when milkiness is global; prefer Color when a whole field is tinted one hue. Courier-damaged laptop lids deserve a dark-room gray pass before you accept “cosmetic only” language. After aggressive cleaning, recheck, wipe marks mimic DSE until coatings recover evenly. Photographers soft-proofing on an unknown lounge display should glance at medium gray for dirty-screen texture before trusting subtle gradient edits on that glass.

How it works

A constant RGB gray is composited fullscreen. Your eyes detect luminance and chromatic unevenness. No permissions. Cameras used for RMA should be careful with exposure, phone auto-HDR invents clouds. Remote desktop compression creates false blotches. OLED ABL can subtly reshape large gray fields over time. A constant RGB gray is composited fullscreen; your eyes detect luminance and chromatic unevenness the browser cannot meter like a lab camera. No permissions are required. Phone auto-HDR invents clouds in RMA photos, prefer careful exposure or rely on visual notes when policies allow. Remote desktop compression creates false blotches; always inspect locally. Native resolution and 100% browser zoom keep scalers from soft-filtering texture. Multi-monitor ambient differences skew perception, match bias lighting when comparing units. Fullscreen requestFullscreen helps hide browser chrome so edge bleed is not mistaken for UI shadowing from a bookmarks bar.

Step-by-step instructions

1. Clean the screen, darken the room, and open Monitor Uniformity Test fullscreen at your typical brightness.
2. View a medium gray field on-axis and note blotches, tint patches, or vignetting.
3. Repeat with darker grays to emphasize backlight bleed at edges.
4. If discrete dots appear, switch to Dead or Dead Pixel Tests; if rings appear, use Gradient Test.
5. Photograph carefully only if your vendor wants evidence, avoiding heavy phone processing when possible.
6. Exit when finished; no permission revoke is required.

Common problems

Dust and coating wipe marks look like DSE. Off-axis IPS glow is normal-ish at extremes, check policy before RMA. Bright rooms hide bleed. Claiming numeric uniformity percentages from eyeballing is invalid. Dual-monitor ambient light differences skew perception. Dust and coating wipe marks look like dirty-screen effect until cleaned carefully. Off-axis IPS glow is often within policy at extremes, read tolerances before RMA. Bright rooms hide bleed. Claiming numeric uniformity percentages from eyeballing is invalid. Smudges from forehead oils on laptop panels create repeating blotches that move when wiped, confirm before blaming backlight. Polarizing sunglasses can make IPS panels look uneven in ways unrelated to backlight; remove them before judging.

Privacy explanation

Flat fields render locally. DeviceHub does not upload zone maps. No camera permission is required for the test UI. Close the tab when done. Flat fields render locally; DeviceHub does not upload zone maps. No camera permission is required for the test UI. Close the tab when done; screenshots you take for vendors remain your files. Vendor RMA uploads are your responsibility; DeviceHub does not mediate those transfers or store zone photographs on your behalf. Side-by-side unit comparisons during return windows work best when both panels share brightness, picture mode, and room lighting, otherwise blotch severity is impossible to rank fairly. Photographers hunting dirty-screen effect should use medium gray and resist phone auto-HDR, which invents clouds that the eye did not see. If discrete bright or dark dots appear while scanning gray, jump to Stuck or Dead Pixel Test rather than calling every speck a uniformity failure.