How to fix lines in webcam video

The short answer

Lines in webcam video usually come from one of four sources. Lighting flicker causes horizontal bands that often roll slowly up or down. Moiré is a wavy or grid-like pattern that appears when the camera films fine detail such as printed documents, fabric or another screen. Compression causes blocky or streaky lines that show up mostly in calls or recordings. A hardware or connection problem causes lines, colored stripes or glitchy rows that stay put whatever you film. The fix depends on which one you have, so first look closely at how the lines behave.

If you are holding a document, receipt, ID card or printed photo up to the camera and the lines appear only on that item, moiré or flicker is the most likely explanation. A broken camera is less likely in that case.

Before you start

• Open a view that shows the camera feed directly, such as your operating system's camera app or the camera software that came with the webcam, and keep it open while you test.
• If the camera does not appear at all, solve that first. Camera access and permissions are a separate problem from image quality.
• Have the item you want to show nearby, such as a document, card or photo, so you can test with the real subject.
• Note which app you see the lines in. Some causes affect only one call app or only recordings.

Step 1: Describe what the lines look like

Each pattern below points to a different group of likely causes. Treat these as starting points, not diagnoses.

• Horizontal bands that drift, roll or pulse, especially under indoor lights: likely lighting flicker.
• Wavy, curved, rainbow-tinged or grid patterns on a printed page, patterned clothing or a monitor, which shift when you move the item: likely moiré.
• Lines or blocks that appear mainly during movement, or only in a call or recording and not in the camera's own preview: likely compression or bandwidth limits.
• Lines, stripes or corrupted rows in the same place regardless of what you film or how you light it: possibly a connection, driver or hardware fault.
• Soft streaks, haze or smears that stay fixed in the frame: possibly a dirty lens, a smudged privacy cover or a scratch.

Step 2: Fix horizontal bands from lighting flicker

Many indoor lights, including some LED bulbs and fluorescent tubes, brighten and dim very rapidly in step with the mains electricity supply. In the US the supply runs at 60 Hz, so this kind of flicker happens 120 times per second. Your eyes may not notice it. A webcam sensor reads the image row by row, so if the light changes while the frame is being read, you get dark and light horizontal bands.

• Look for an anti-flicker or power line frequency setting in your webcam software or the call app's video settings, and set it to 60 Hz if you are in the US. Not every camera or app offers this, and menu names vary.
• If there is a manual exposure control, try turning off automatic exposure and adjusting it. Exposure times that line up with the light's flicker cycle reduce banding. An anti-flicker setting, if available, does this for you.
• Switch off the light that seems to cause the bands, or replace it with daylight from a window or a different lamp.
• Avoid dimmed LED lights. Dimmers can make flicker more noticeable to a camera.
• Move the document closer to a steady light source so the camera needs less correction.

How to tell it worked: the bands stop moving or disappear in the live preview. Also check by turning the suspect light on and off. If the bands come and go with that light, you have confirmed the cause.

Step 3: Fix moiré when showing documents and close-up items

Moiré is an interference pattern. It forms when fine, regular detail in the subject clashes with the regular grid of pixels in the camera sensor. Printed material often uses tiny dot patterns to reproduce images and shading, and screens are made of pixel grids, so both commonly trigger it. Fine text, ruled lines and security patterns on cards can do the same.

• Change the distance. Move the item slightly closer to or farther from the camera. Moiré often appears at one distance and vanishes at another.
• Tilt or rotate the item a few degrees so its lines no longer run parallel to the camera's rows of pixels.
• Use the camera's full resolution if your app lets you choose it, and avoid digital zoom. Digital zoom enlarges pixels and can make the pattern worse.
• Move the camera, not just the zoom level. If you need the item larger in frame, bring it closer within the range where the camera can still focus.
• Hold the item steady or rest it on a surface so autofocus can lock on. A sharp, stable image is easier to judge and less likely to shimmer.
• For anything on a computer or phone screen, share the screen or send the file instead of filming the display. Filming a screen almost always produces some moiré or scan lines.
• If you need a clean copy of a document rather than just showing it, consider taking a still photo or scan and sharing that. Live video is not ideal for fine print.

How to tell it worked: the pattern is gone in the live preview and stays gone when you move the item slightly. Call apps often resize and compress video, which can create moiré that was not visible locally, so confirm with a test recording or a test call as described below.

Step 4: Lines that appear only in calls or recordings

If the camera preview looks clean but lines, blocks or streaks appear in a call or recording, the camera is capturing correctly. The problem is in how the video is processed, compressed or sent. This is a call quality issue, not a camera fault.

• Compare the same scene in the camera preview and in the call app. If only the call looks wrong, focus on the app and the connection.
• Turn off video effects such as background blur, virtual backgrounds, beauty filters or lighting correction, then check again. These effects can add artifacts, especially around edges and fine detail like text.
• Close other apps and browser tabs that use the camera, the network or a lot of processing power.
• Use a wired network connection or move closer to your router if possible, then retest.
• If the app lets you choose a video quality or resolution setting, try a higher one for showing documents. If your connection struggles, try a lower one, which may give fewer motion artifacts.
• Try a different app or the browser version of the same service to see whether the lines follow the camera or stay with the app.

Step 5: Fixed lines, colored stripes or glitchy rows

Lines that stay in the same place whatever you point the camera at, and regardless of lighting, suggest a connection, driver or hardware problem. Work through these reversible checks in order.

• Clean the lens and any privacy cover gently with a soft, dry lens cloth. Fixed haze or streaks sometimes come from fingerprints or smudges.
• For a USB webcam, unplug it and plug it directly into a different port on the computer instead of a hub, extension cable or dock.
• If the cable is detachable, try a different cable.
• Restart the computer, then test again in the operating system's own camera app.
• Check for operating system and camera driver updates, and for updates to any camera software the manufacturer provides.
• Try the camera on a different computer if you can.

How to read the results: if the lines disappear with a different port or cable, the original connection was likely the cause. If they appear on every app and every computer with the same camera, the camera itself is the likely fault. For a laptop's built-in camera, try an external webcam. If the external camera is clean, the built-in camera or its internal connection may need repair.

Confirm the fix with a final test

A clean local preview shows that the camera is capturing a clean image under your current lighting and setup. It does not show what other people will see, because call apps resize and compress video before sending it. To check that, make a short test recording in the app you plan to use, or join a test call with someone who can describe what they see. Show the actual document or item at the distance and angle you intend to use, and move it slightly to see whether lines or patterns reappear.

When to escalate

Contact the camera or computer manufacturer, or consider a replacement, if fixed lines or stripes persist across different ports, cables, apps and computers. If the lines appear only in one call service and you have ruled out your connection and video effects, that service's support team is the appropriate next step.

Limits of this guide

No model-specific settings, recommended exposure values or measured test results were available for this guide. Whether your webcam offers anti-flicker, manual exposure or resolution controls, and where those settings are located, depends on the camera, its software and the app you use. Check the manufacturer's documentation for your exact model.