Contrast: Definition, issues, and explanations

Contrast refers to the visual difference between two graphic elements, such as color, brightness, size, or shape, used to clearly distinguish them from one another. In UI/UX design, it is a principle that makes an interface more readable, understandable, and enjoyable to use.

Contrast can be achieved by juxtaposing light and dark colors, different shapes, or sizes to draw the user's attention to important elements or visually structure a page.

In ergonomics, contrast is essential for improving visual perception, particularly for people with visual impairments, and for ensuring an optimal user experience.

Contrast is essential for facilitating the reading and comprehension of a digital interface. By creating marked differences between elements, it guides the eye and helps to prioritize information.

Its main benefit lies in improving accessibility: good contrast allows people with low vision or color blindness to interpret visual content correctly, ensuring inclusive use.

In addition, contrast enhances the user experience by making interactions more intuitive and preventing visual fatigue when viewing interfaces.

Contrast works primarily through the opposition of visual characteristics such as color, brightness, saturation, size, or shape. For example, a light color on a dark background creates high contrast, which makes reading easier.

In design, contrast analysis tools are often used to verify that color combinations comply with accessibility standards such as WCAG (Web Content Accessibility Guidelines).

Contrast is measured by a ratio that expresses the difference in luminance between two colors. The higher this ratio, the greater the contrast, which is crucial for ensuring good readability and visibility of content.

Among the advantages of contrast are improved readability, clear information hierarchy, and better accessibility for all users, including those with visual impairments.

Well-crafted contrast also improves the overall aesthetics of the design and helps draw attention to important elements such as calls to action.

However, poorly controlled contrast can lead to visual overload or an overly aggressive effect that tires the user. It is therefore necessary to find the right balance to avoid detracting from the user experience.

In web interfaces, contrast is used to differentiate text from the background, for example with black text on a white background or vice versa, to ensure easy reading.

Call-to-action buttons often use high contrast to attract attention and encourage clicks.

Contrast is also used to create visual hierarchies, such as using larger, darker fonts for titles and more neutral colors for the body text.

• WCAG - Guidelines for minimum contrast
• MDN Web Docs - Contrast and accessibility
• WebAIM - Contrast Checker Tool
• Color Oracle - Color Blindness Simulator