HMI - light versus dark design
Article#: 00111
Date: 2025-09-09
Author: Radim
The choice between dark and light design for HMI visualizations is not just a question of appearance.
Both approaches have their advantages and disadvantages, which become apparent depending on the operating environment in which the HMI is used.
Light design (light background, dark text and graphics):
- Very good readability in well-lit environments (e.g., day shift, production hall with sufficient lighting).
- High contrast makes it easier to recognize details and fine lines.
- Dirt (dust, fingerprints, stains) is less noticeable on a light background; legibility only deteriorates if the surface is heavily soiled.
- Disadvantage: In dark environments, the screen can be dazzling and cause eye strain.
Dark design (dark background, light text and graphics - also known as night mode):
- Practical in low light conditions: reduces glare and eye fatigue.
- Can reduce power consumption on OLED/AMOLED displays.
- Disadvantage: Dust, scratches, and grease are more visible on dark backgrounds. They can impair the perceived contrast and legibility of thin elements.
- Disadvantage: More limited selection of clearly recognizable colors for text and curves. Risk of reduced legibility of fine details.
If lighting conditions vary significantly, provide the option to switch between light and dark modes, either manually or automatically.
This ensures sufficient contrast at all times and minimizes glare in dark environments.
However, color consistency must be guaranteed in both modes.
Inconsistent color schemes can have serious consequences: slower or incorrect reactions by the operator, or even production downtime.
Always consider contrasts when creating your design.
Consider dust, smudges and scratches, not just a clean surface.
Test readability with real users in real operating environments (different shifts, lighting conditions, glare, and soiled screens).
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Comment#: 00001
Date: 2025-09-11
User: Radim
Dark design is becoming increasingly popular, mainly because it looks modern and attractive. However, it also has its drawbacks, as mentioned in the article above. Some of them appear over time – for example, scratches and dirt are more visible and disturbing on dark backgrounds.
If we decide to use a dark design, it is also important to set the display brightness correctly: high enough to ensure readability in strong ambient light, and dimmed in dark environments so the screen does not cause glare.