Camera image has color blocks: what to test

Your camera preview shows big colored squares, patches, or blocky sections instead of a clear image. That can come from low light, a video app trying to compress the picture, a loose connection, or a camera fault.

Test the camera outside the app where you noticed the problem. The Camera Test shows a live preview, resolution, and frame rate, which helps you tell whether the blocks follow the camera or only appear in one app.

Test the camera image

1. Open the Camera Test and allow camera access when your browser asks.
2. Put the camera in the same place and lighting where you noticed the blocks. Aim it at a still subject with ordinary details, such as a face or a book cover.
3. Watch the preview for 20 to 30 seconds. Note whether blocks stay in the same place, move with the picture, or appear only when you move the camera.
4. Check the resolution and frame rate shown by the test. Then close the test and compare the camera in the app where you first saw the problem.
5. If possible, compare with another camera or another device in the same room. Keep the lighting and subject similar so the comparison is useful.

Make sure the camera lens is not covered and that the room is reasonably bright. A very dark image can become noisy, and a camera or app may then turn that noise into larger, blocky patches.

What the result means

The Camera Test preview is clear, but one app has blocks

The camera can produce a clean picture, so the fault is more likely in that app's settings, effects, or video connection. A call app may reduce image quality when the connection is weak, or apply a background effect that breaks up parts of the picture. Check its camera selection and video effects, then test again without filters or backgrounds.

The blocks appear in the Camera Test and other camera apps

The problem is likely before the image reaches the app. Possible causes include poor lighting, a camera processing problem, a loose cable, or a fault in the camera. If the blocks change when you move the camera or adjust the light, start with the fixes below.

The blocks stay in the same place

A patch that remains fixed in one part of the image across different apps and lighting may point to a camera sensor or internal processing fault. A single faulty pixel is usually much smaller than a large block, so a group of colored squares is not the same as one dead pixel.

The frame rate drops while the blocks appear

The camera may be struggling to send a steady stream of video. Another app could be using the camera, or a USB connection may not have enough bandwidth. Close other camera apps and reconnect an external webcam before deciding that the camera is damaged.

How to fix it

1. Improve the lighting. Face a window or turn on a room light, and avoid a bright window directly behind you. Test again without changing other settings. If the blocks clear up, low light or the camera's automatic image processing was likely involved.
2. Turn off effects and filters. In the video app, disable background blur, virtual backgrounds, beauty filters, and other image effects. These features process the camera image and can create artifacts even when the original preview is fine.
3. Allow camera access. In your browser, open the site permissions from the icon beside the address bar and set Camera to Allow. On Windows 11, check Settings › Privacy & security › Camera. On macOS, check System Settings › Privacy & Security › Camera and allow your browser. On iPhone, check Settings › Privacy & Security › Camera. On Android, check Settings › Security & privacy › Privacy controls › Camera access; the exact labels can vary by phone.
4. Close other apps using the camera. Quit video calls, camera apps, and browser tabs that may be using it, then reload the test. If the camera works after that, reopen the apps one at a time to find which one causes the problem.
5. Reconnect an external webcam. Unplug it and connect it directly to another USB port, rather than through a hub or dock. Try another cable if the webcam has a removable one. A built-in laptop camera has no external cable to reseat.
6. Check for camera settings or driver updates. On Windows 11, open Settings › Bluetooth & devices › Cameras to see the connected camera and any available camera controls. Install camera or system updates offered by your computer maker. On macOS, install available updates through System Settings › General › Software Update.
7. Restart the device. A restart can release a camera that another app has left in a bad state. After restarting, test the camera before opening your video call app.

When it's likely a camera fault

If the same large blocks appear in the Camera Test and in more than one camera app, even in good light, the camera itself or its connection may be damaged. For an external webcam, test it on another computer if you can. If the blocks follow the webcam, check its warranty or replace it. If the built-in camera shows the same fault across apps, contact the device maker or a repair shop.

The Camera Test shows a live preview in your browser, so you can check the image without making a recording.