How to use this tool
- Run the tool or load the example, then choose Start screen test. The view begins with white.
- Inspect each area of the display. Use Next color, Previous, arrow keys or Space to change the background at your own pace.
- Choose End test or press Esc to close the view. Repeat a color if you want to compare a particular screen location.
Check the built-in example
The example prepares the controls without entering fullscreen automatically. Start opens a white field. One next step changes it to black; a second changes it to red. Green, blue and gray follow, then the sequence returns to white. These are six requested display colors, not six measurements of panel condition. The software never records how many suspicious dots you observe.
Processing method
A screen-covering element receives a solid CSS background. The color values are white #ffffff, black #000000, red #ff0000, green #00ff00, blue #0000ff and gray #808080. A user action requests the browser Fullscreen API documented below. If that request is unavailable or rejected, the element covers the browser viewport instead. A control panel remains visible at the bottom. Keyboard focus stays within the test controls while the view is open. Color changes happen only after a button or keyboard command; there is no timer or flashing mode.
Reference: MDN: Fullscreen API and browser support
What the result leaves out
This is a visual aid rather than automatic hardware diagnosis. Browser chrome, unsupported fullscreen modes and the control panel can prevent complete physical-screen coverage. Operating-system scaling, display processing and the panel affect what you see. This tool does not measure brightness, color accuracy, response time or refresh rate. It cannot repair pixels, classify defects for a warranty claim or establish that a monitor is fault-free. A screenshot records the browser image rather than proving the state of the physical panel. Inspect the actual display yourself and distinguish a screen mark from a visible surface obstruction.
Checking local processing
No image, screen recording or screen-capture permission is requested. The selected color and control state stay in page memory. This site serves the interface assets; the test does not send observations or screenshots to a server. Close the test to return keyboard focus to its start button. Reset removes the current controls, and leaving the page cleans up the screen view.
Common questions
Will it find faulty pixels automatically?
No. You inspect the physical display; the page does not read or classify hardware pixels.
Do colors flash or cycle on their own?
No. Every color change requires a button or keyboard command.
Why can browser controls remain visible?
Fullscreen support varies. The fallback covers only the browser viewport, and the test control panel remains visible.