FastLED Color Specialist Skill

FastLED Color Specialist Skill

Expert guidance on FastLED color theory, color space mathematics, palette design, and performance optimization.

When to Use This Skill

This skill should be triggered when:

• Designing color palettes and harmonious color schemes for LED animations
• Converting between color spaces (RGB/​HSV/​HEX) or blending colors
• Optimizing color performance for constrained hardware
• Debugging color issues in LED effects (unexpected colors, banding, flicker)
• Understanding gamma correction, color perception, and visual effects
• Creating gradient chains and multi-effect color transitions

Quick Reference

Color Space Conversions

RGB to HSV:

// FastLED provides CHSV type for HSV colors
CHSV color_hsv = rgb2hsv_approximate(CRGB(255, 128, 0)); // Orange
// H: 0-255 (0° = red, 85° = green, 170° = blue)
// S: 0-255 (0 = white, 255 = saturated)
// V: 0-255 (0 = black, 255 = bright)

HSV to RGB:

CRGB color_rgb = CHSV(42, 255, 255); // Bright yellow

HEX to RGB:

// Common FastLED web colors
CRGB red = CRGB::Red;        // 0xFF0000
CRGB blue = CRGB::Blue;      // 0x0000FF
CRGB custom = CRGB(0xAA, 0xBB, 0xCC); // Define custom

Palette Generation Patterns

Complementary (2 colors, high contrast):

// Pick primary color in HSV, add 128 to hue for opposite
CHSV primary(30, 255, 255);      // Orange
CHSV complement(158, 255, 255);  // Blue-green (30 + 128 = 158)

Triadic (3 colors, balanced energy):

// Equally spaced 85° apart (255/​3 = 85)
CHSV color1(0, 255, 255);    // Red
CHSV color2(85, 255, 255);   // Green
CHSV color3(170, 255, 255);  // Blue

Analogous (3 colors, harmonious):

// Colors 30° apart (adjacent on color wheel)
CHSV primary(60, 255, 255);   // Yellow
CHSV left(30, 255, 255);      // Yellow-orange
CHSV right(90, 255, 255);     // Yellow-green

Tetradic (4 colors, complex):

// Two complementary pairs (85° spacing, doubled)
CHSV c1(0, 255, 255);     // Red
CHSV c2(85, 255, 255);    // Green
CHSV c3(128, 255, 255);   // Cyan (complement of Red)
CHSV c4(213, 255, 255);   // Magenta (complement of Green)

Color Blending

Linear interpolation (blend two colors):

CRGB blend(CRGB color1, CRGB color2, uint8_t position) {
  // position: 0 = color1, 128 = middle, 255 = color2
  return blend8(color1, color2, position);
}

Gradient (smooth transition across array):

fill_gradient_RGB(leds, NUM_LEDS, CRGB::Red, CRGB::Blue);
// Smooth transition from red to blue across all LEDs

Color cycling (fade in/​out):

// HSV allows easy brightness variation
CHSV color(Hue, Saturation, brightness); // Adjust value/​brightness
fadeToBlackBy(leds, NUM_LEDS, fade_amount); // Dim all

Gamma Correction

Why it matters: Human eyes perceive brightness non-linearly. Gamma correction makes colors look natural.

// FastLED applies gamma correction with proper scaling
// Use these gamma tables for consistency:
const uint8_t gamma8[] = { /​* lookup table */ };

// Apply to single LED
leds[0] = CRGB(gamma8[r], gamma8[g], gamma8[b]);

Performance Optimization

Memory efficient patterns:

• Use CHSV instead of CRGB when storing palettes (3 bytes vs 3 bytes, but more efficient for color manipulation)
• Use color arrays instead of generating colors in loops
• Pre-calculate palettes during setup, not in the render loop

Speed optimization:

• rgb2hsv_approximate() is faster than rgb2hsv()
• Use fill_solid() and fill_gradient_RGB() for bulk operations
• Pre-allocate arrays instead of using vectors in hot loops

Color order (critical for some LED types):

// Define color order for your LED type (often RGB or GRB)
FastLED.addLeds<WS2812B, DATA_PIN, GRB>(leds, NUM_LEDS);

Reference Files

Reference documentation in references/:

• color_theory.md - Color theory fundamentals and perception
• color_spaces.md - RGB, HSV, HEX explained with conversion formulas
• palette_patterns.md - Design patterns for harmonious palettes
• blending_gradients.md - Color blending, gradients, and transitions
• performance_tips.md - Memory and speed optimization
• debugging_colors.md - Troubleshooting common color issues
• web_colors_reference.md - FastLED web color table
• gamma_correction.md - Gamma tables and brightness perception

Working with This Skill

Quick Color Problem?

Check the Quick Reference section above for immediate patterns.

Need Deep Dive?

Use reference files for:

• Detailed color theory and human perception
• Mathematical formulas for color conversions
• Systematic debugging approaches for color issues
• Performance optimization for constrained systems

Code Examples?

All reference files contain practical code examples you can copy and adapt.

Resources

references/

Comprehensive documentation covering:

• Color theory and perception
• Color space mathematics and conversions
• Palette design patterns with psychological impact
• Blending and gradient techniques
• Performance optimization strategies
• Debugging methodologies
• Reference tables (web colors, gamma values)

assets/

• Color palette templates
• Gamma correction lookup tables
• Example animation effects with colors
• Performance benchmarking templates

scripts/

Helper utilities for:

• Converting colors between formats
• Generating palette variations
• Testing color perception

Common Use Cases

"I want vibrant, energetic colors" → Triadic or tetradic palettes with high saturation "I want calming, natural colors" → Analogous palettes with mid saturation "I need high contrast" → Complementary pairs "Colors look wrong/​washed out" → Check gamma correction and color order "Animation is slow" → Optimize palette generation, use pre-calculated colors "Banding/​posterization visible" → Use HSV color space for smoother gradients

Integration with FastLED Skill

This skill is specialized for color work. For general FastLED questions (library setup, LED control, timing), refer to the general FastLED skill.

Notes

• All code examples assume FastLED library is properly included and initialized
• Color math works identically on all FastLED-supported platforms
• Performance tips assume typical microcontroller constraints (ESP32, Arduino)
• Perception examples assume typical human color vision

Quick Debugging Checklist

• Check color order (RGB vs GRB) matches your LED type
• Verify brightness/​value isn't 0 (invisible color)
• Check saturation - low saturation = grayish/​washed out
• Apply gamma correction for natural-looking colors
• Test with single LED before full animation
• Monitor memory/​CPU if animation sluggish