Color Picker & Contrast

Color contrast describes the brightness difference between foreground text and background colors, usually expressed as a ratio (e.g., 4.5:1). Higher contrast makes text visually clearer and improves reading experience; insufficient contrast may make content completely unrecognizable to low-vision users.

Approximately 253 million people worldwide live with some form of visual impairment (including myopia, hyperopia, color blindness, cataracts, etc.). Ensuring website content is readable for these users is a basic requirement of accessibility design. WCAG 2.1 (Web Content Accessibility Guidelines) is currently the most authoritative and widely adopted web content accessibility standard globally.

An often overlooked fact: in bright lighting conditions (such as direct sunlight on screens), old low-brightness devices, or long reading sessions, insufficient contrast is equally unfriendly to normal vision users. Improving contrast not only enhances accessibility but also shows respect for all users.

WCAG 2.1 defines two compliance levels (AA and AAA), as well as different thresholds for normal text and large text:

AA Level (Basic Compliance): Normal text requires contrast ≥ 4.5:1; large text (18pt or larger, or 14pt or larger if bold) requires contrast ≥ 3:1.

AAA Level (Highest Compliance): Normal text requires contrast ≥ 7:1; large text requires contrast ≥ 4.5:1. In government and enterprise-level projects, many clients and legal teams require achieving AAA level.

The contrast calculation formula is based on "Relative Luminance": first normalize RGB values and apply gamma correction, then calculate luminance weighted by red 0.2126, green 0.7152, blue 0.0722, and finally divide "(brighter luminance + 0.05)" by "(darker luminance + 0.05)" to get the ratio.

Extracting primary colors, accent colors, and neutral colors from photography works, design drafts, and brand visuals is daily work for designers and front-end engineers. The core principle is: do not judge by naked eye — always verify with tools. Subjectively perceived "vibrant" and objectively calculated "contrast" are often inconsistent.

Some common color-picking mistakes to note: picking colors in color transition areas (gradient edges) may yield unstable intermediate colors; picking from zoomed-in images may be distorted due to pixel averaging; choosing bright light yellow/light green colors often have severely insufficient contrast on white backgrounds.

All color picking and calculations in this tool are completed locally in your browser — no image upload, no content retention, no local storage writing. Works normally even when offline. For images involving brand secrets, it is recommended to operate in a controlled environment.