A tiny mark on a new monitor can be dust, an image artifact or a pixel that does not display the expected color. A busy wallpaper makes these hard to distinguish.
Screen Lab fills the display with simple test patterns so you can inspect it visually. Start with solid colors, then use gray steps and other patterns for a closer look. The app does not automatically detect or repair defective pixels.
Prepare the display
Open Screen Lab in Aelrox. Move its window to the monitor you want to inspect before selecting Start fullscreen test.
Clean the screen according to its manufacturer's instructions first. Dust can resemble a pixel defect. Use a comfortable brightness and check the display's resolution and scaling settings. The app's canvas size and device-pixel ratio are useful context, but they are not a guarantee of one canvas pixel per physical panel pixel.
Inspect white, black and primary colors
Select Solid colors. Examine white, black, red, green and blue, looking for a spot that stays dark or keeps an unexpected color as the background changes. Move your attention across the screen systematically rather than rapidly switching colors.
| Pattern | What to look for |
|---|---|
| White | Small dark spots or visibly uneven areas |
| Black | Unexpected bright spots and uneven light in a dim room |
| Red, green, blue | Spots that fail to follow the selected color |
These are observations, not automatic diagnoses. Viewing angle, reflections, brightness and the panel technology can affect what you see. Keep those conditions similar when comparing patterns.
Screen Lab 1.0.0 uses static patterns without automatic flashing. Use the color controls or the arrow keys to change colors manually. Allow the controls to hide while inspecting; press Esc when you want to leave fullscreen.
Use other patterns for a second look
Gray steps separates discrete gray levels; Smooth gradient provides a continuous transition to inspect. Pixel grid, Checkerboard and Text & sharpness offer different high-contrast details.
If fine patterns look soft or uneven, check display scaling and resolution before deciding the panel is defective. These patterns are not an HDR, color-accuracy or refresh-rate measurement, and they do not replace calibration equipment.
Record a physical issue with a camera
If you see a persistent spot, note its approximate position and the colors on which it appears. Photograph the actual display if you need to document a suspected panel defect. A software screenshot captures the image sent to the screen; it will not record a physical pixel failing to show that image.
Do not use a clean screenshot as evidence that the monitor has no defective pixels. Conversely, one photograph is not enough to identify every kind of panel issue. Review the monitor maker's support and pixel policy for next steps.
Use Screen Lab to create a consistent view for inspection. The useful result is a specific observation you can repeat, rather than an unsupported pass/fail verdict.