Color Tools
Compute color math; don't eyeball hex values.
HEX ↔ RGB ↔ HSL
python3 - <<'PY'
import colorsys
def hex_to_rgb(h): h=h.lstrip('#'); return tuple(int(h[i:i+2],16) for i in (0,2,4))
def rgb_to_hex(r,g,b): return '#%02x%02x%02x'%(r,g,b)
r,g,b = hex_to_rgb('#3b82f6')
h,l,s = colorsys.rgb_to_hls(r/255,g/255,b/255)
print('rgb', (r,g,b))
print('hsl', (round(h*360), round(s*100), round(l*100)))
print('hex', rgb_to_hex(r,g,b))
PY
Lighten / darken (adjust HSL lightness)
python3 - <<'PY'
import colorsys
def adjust(hex_, dl):
h=hex_.lstrip('#'); r,g,b=(int(h[i:i+2],16)/255 for i in (0,2,4))
H,L,S=colorsys.rgb_to_hls(r,g,b); L=max(0,min(1,L+dl))
r,g,b=colorsys.hls_to_rgb(H,L,S); return '#%02x%02x%02x'%(int(r*255),int(g*255),int(b*255))
print('lighter', adjust('#3b82f6', +0.15))
print('darker ', adjust('#3b82f6', -0.15))
PY
Contrast ratio (accessibility, WCAG)
python3 - <<'PY'
def lin(c): c/=255; return c/12.92 if c<=0.03928 else ((c+0.055)/1.055)**2.4
def lum(h): h=h.lstrip('#'); r,g,b=(int(h[i:i+2],16) for i in (0,2,4)); return 0.2126*lin(r)+0.7152*lin(g)+0.0722*lin(b)
def ratio(a,b): L1,L2=sorted([lum(a),lum(b)],reverse=True); return (L1+0.05)/(L2+0.05)
r=ratio('#ffffff','#3b82f6'); print(f'contrast {r:.2f}:1', '(AA body needs >=4.5)')
PY
Guidance
- Palettes: complementary = +180° hue; analogous = ±30°; triadic = ±120°.
- For body text, aim for contrast ≥ 4.5:1 (AA); ≥ 3:1 for large text.
- Always state colors as hex in the answer so they're copy-pasteable.
1---2name: color-tools3description: Work with colors: convert between HEX/RGB/HSL, build palettes, find complementary/analogous colors, and check text contrast for accessibility (WCAG). Use when users ask to convert a color, lighten/darken it, build a color scheme, or check if a color combo is readable. Triggers on mentions of color, colour, hex, rgb, hsl, palette, contrast, complementary, shade, 颜色, 配色, 色值, 对比度, 调色板.4license: Proprietary. LICENSE.txt has complete terms5---67# Color Tools89Compute color math; don't eyeball hex values.1011## HEX ↔ RGB ↔ HSL1213```bash14python3 - <<'PY'15import colorsys16def hex_to_rgb(h): h=h.lstrip('#'); return tuple(int(h[i:i+2],16) for i in (0,2,4))17def rgb_to_hex(r,g,b): return '#%02x%02x%02x'%(r,g,b)18r,g,b = hex_to_rgb('#3b82f6')19h,l,s = colorsys.rgb_to_hls(r/255,g/255,b/255)20print('rgb', (r,g,b))21print('hsl', (round(h*360), round(s*100), round(l*100)))22print('hex', rgb_to_hex(r,g,b))23PY24```2526## Lighten / darken (adjust HSL lightness)2728```bash29python3 - <<'PY'30import colorsys31def adjust(hex_, dl):32 h=hex_.lstrip('#'); r,g,b=(int(h[i:i+2],16)/255 for i in (0,2,4))33 H,L,S=colorsys.rgb_to_hls(r,g,b); L=max(0,min(1,L+dl))34 r,g,b=colorsys.hls_to_rgb(H,L,S); return '#%02x%02x%02x'%(int(r*255),int(g*255),int(b*255))35print('lighter', adjust('#3b82f6', +0.15))36print('darker ', adjust('#3b82f6', -0.15))37PY38```3940## Contrast ratio (accessibility, WCAG)4142```bash43python3 - <<'PY'44def lin(c): c/=255; return c/12.92 if c<=0.03928 else ((c+0.055)/1.055)**2.445def lum(h): h=h.lstrip('#'); r,g,b=(int(h[i:i+2],16) for i in (0,2,4)); return 0.2126*lin(r)+0.7152*lin(g)+0.0722*lin(b)46def ratio(a,b): L1,L2=sorted([lum(a),lum(b)],reverse=True); return (L1+0.05)/(L2+0.05)47r=ratio('#ffffff','#3b82f6'); print(f'contrast {r:.2f}:1', '(AA body needs >=4.5)')48PY49```5051## Guidance5253- Palettes: complementary = +180° hue; analogous = ±30°; triadic = ±120°.54- For body text, aim for contrast ≥ 4.5:1 (AA); ≥ 3:1 for large text.55- Always state colors as hex in the answer so they're copy-pasteable.
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