# Duotone Design

> Web and App implementation guide for Duotone Design. Trigger when user wants two-color schemes, striking imagery, and Spotify-like playlist aesthetics.

- Skill: `ranbot-ai/duotone-design` (Agent Skill)
- Install (CLI): `npx skillmds add ranbot-ai/duotone-design`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ranbot-ai/duotone-design/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ranbot-ai (https://skillmd.com/u/ranbot-ai)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ranbot-ai/duotone-design

---



# Duotone Design

> "Striking contrast. Photography and UI stripped down to exactly two clashing or complementary colors."


## When to Use
Use this sub-style when the user's request matches the aesthetic described above. This is a child reference of the `design-it` skill and is not meant to be triggered directly.

## Core Principles
1. **Two Colors Only**: The entire design is mapped to a dark color (replacing blacks/shadows) and a light color (replacing whites/highlights).
2. **Treated Imagery**: All photos MUST be processed into the duotone palette.
3. **Bold, Flat Typography**: Text is usually massive, solid, and uses one of the two colors.

## Visual DNA
- **Colors**: Very high contrast pairs. Navy and Peach, Deep Purple and Neon Green, Crimson and Cream. Look at **Industrial Chic** for inspiration.
- **Typography**: Heavy, condensed sans-serifs (e.g., `League Gothic`, `Oswald`).
- **Imagery**: High-contrast, gritty photography works best when mapped to duotone.

## Web Implementation
- Modern CSS can achieve image duotone effects without Photoshop, using `mix-blend-mode` and filters.
- **CSS Example**:
```css
:root {
  --duo-dark: #1E0045; /* Deep Purple */
  --duo-light: #CCFF00; /* Neon Lime */
}

body {
  background-color: var(--duo-dark);
  color: var(--duo-light);
}

/* CSS Duotone Image Effect */
.duotone-container {
  position: relative;
  width: 100%;
  height: 400px;
  background-color: var(--duo-light); /* Base color */
}

.duotone-container img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  /* Convert image to grayscale, increase contrast */
  filter: grayscale(100%) contrast(1.5); 
  /* Multiply the grayscale image against the light background */
  mix-blend-mode: multiply;
}

.duotone-container::after {
  /* Overlay the dark color using screen/lighten */
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background-color: var(--duo-dark);
  mix-blend-mode: screen;
}

.duotone-btn {
  background: var(--duo-light);
  color: var(--duo-dark);
  border: none;
  font-weight: 900;
  text-transform: uppercase;
  padding: 16px 32px;
}
```

## App Implementation

### SwiftUI
```swift
struct DuotoneImage: View {
    let duoDark = Color(red: 0.12, green: 0.0, blue: 0.27)  // #1E0045
    let duoLight = Color(red: 0.8, green: 1.0, blue: 0.0)   // #CCFF00
    
    var body: some View {
        ZStack {
            // Background base color
            duoLight.ignoresSafeArea()
            
            // Image processing
            Image("sample_photo")
                .resizable()
                .scaledToFill()
                .grayscale(1.0)
                .contrast(1.5)
                .colorMultiply(duoLight) // Multiplies the light color into the grays
            
            // Dark color overlay
            duoDark
                .blendMode(.screen) // Equivalent to CSS screen blend mode
                .allowsHitTesting(false)
        }
        .frame(height: 400)
        .clipped()
    }
}
```
- Real-time image processing is easy in SwiftUI.
- Convert to `.grayscale()`, boost `.contrast()`, then use `.colorMultiply()` and `.blendMode(.screen)` layers to map the two colors exactly like CSS `mix-blend-mode`.

### Flutter
```dart
class DuotoneImage extends StatelessWidget {
  final Color duoDark = const Color(0xFF1E0045);
  final Color duoLight = const Color(0xFFCCFF00);

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 400,
      width: double.infinity,
      color: duoLight,
      child: Stack(
        fit: StackFit.expand,
        children: [
          // 1. Grayscale & Contrast (using ColorFilter matrix)
          // 2. Light Color Multiply
          ColorFiltered(
            colorFilter: ColorFilter.mode(duoLight, BlendMode.multiply),
            child: ColorFiltered(
              // Simple grayscale matrix
              colorFilter: const ColorFilter.matrix([
                0.2126, 0.7152, 0.0722, 0, 0,
                0.2126, 0.7152, 0.0722, 0, 0,
                0.2126, 0.7152, 0.0722, 0, 0,
                0,      0,      0,      1, 0,
              ]),
              child: Image.asset('assets/sample_photo.jpg', fit: BoxFit.cover),
            ),
          ),
          // 3. Dark Color Screen Overlay
          ColorFiltered(
            colorFilter: ColorFilter.mode(duoDark, BlendMode.screen),
            child: Container(color: Colors.transparent), // Applies filter to stack below
          ),
        ],
      ),
    );
  }
}
```
- Flutter requires stacking `ColorFiltered` widgets.
- Use a `ColorFilter.matrix` to convert the image to grayscale first.
- Apply `BlendMode.multiply` with the light color, then overlay the dark color using `BlendMode.screen`.

### React Native
```jsx
// Real-time CSS-like blend modes do NOT exist natively in React Native.
// You must use react-native-skia or pre-process images.

import { Canvas, Image, useImage, ColorMatrix } from "@shopify/react-native-skia";

const DuotoneIma