Pang-bô͘:Greater color contrast ratio

Pang-bô͘ bûn-su[chhâ-khòaⁿ] [pian-chi̍p] [le̍k-sú] [kun-sin]

This template determines the pair of colors with the larger contrast ratio: color1/color2 or color1/color3. This is useful for selecting a foreground/background color pair. For accessibility, WCAG 2.0 AA guidelines require a contrast ratio of 3 or larger for large text, and 4.5 or larger for normal sized text.

In the default mode, color2 and color3 are white and black, and the selected color pair will always have a contrast ratio greater than 4.58.

Parameters

A color input can be by name ("khaki") or hextriplet with/without #-prefix ("#F0E68C", "F0E68C")   

|1= (required): background color

|2= first fontcolor. Optional, default = white (#FFFFFF)

|3= second fontcolor. Optional, default = black (#000000)

The template returns the fontcolor with the greatest contrast

background is   Khaki (#F0E68C): {{Greater color contrast ratio|khaki|white|black}} → black

background is   RoyalBlue (#4169E1): {{Greater color contrast ratio|#4169E1|FFFFFF|000000}} → FFFFFF (=white)

css text

• |css=y makes the template return css-ready text:

  Khaki (#F0E68C): {{Greater color contrast ratio|khaki|white|black|css=y}}

→ background-color:khaki; color:black;

Example 1,   Khaki (#F0E68C)

<span style="font-size:110%; {{Greater color contrast ratio|khaki|white|black|css=y}}">Example text on khaki background.</span>

→ <span style="font-size:110%; background-color:khaki; color:black;">Example text on khaki background.</span>

→ Example text on khaki background.

Example 2,   #4169E1 (RoyalBlue)

<span style="font-size:110%; {{Greater color contrast ratio|#4169E1|#ffffff|#000000|css=y}}">Example text on #4169E1 background.</span>

→ <span style="font-size:110%; background-color:#4169E1; color:#ffffff;">Example text on #4169E1 background.</span>

→ Example text on #4169E1 background.

bias

• |bias=number: reduces contrast-check. A bias of 1.25, reduces the possible minimum to 4.0, which may not meet accessibility standards.

This parameter should be used with caution to ensure accessibility. As stated above, when used without a bias, and with color2 and color3 equal to white and black, the selected color pair will always have a contrast ratio greater than 4.58.

Examples

Navy

• <span style="background:navy; color:{{Greater color contrast ratio|navy|white|black}}">Navy</span> → Navy
• <span style="{{Greater color contrast ratio|navy|white|black|css=y}}">Navy</span> → Navy
• <span style="{{Greater color contrast ratio|navy|css=y}}">Navy</span> → Navy

Red

• <span style="background:red; color:{{Greater color contrast ratio|red|white|black}}">Red</span> → Red
• <span style="{{Greater color contrast ratio|red|white|black|css=y}}">Red</span> → Red
• <span style="{{Greater color contrast ratio|red|css=y}}">Red</span> → Red

White

• <span style="background:white; color:{{Greater color contrast ratio|white|white|black}}">White</span> → White
• <span style="{{Greater color contrast ratio|white|white|black|css=y}}">White</span> → White

Black

• <span style="background:black; color:{{Greater color contrast ratio|black|white|black}}">Black</span> → Black
• <span style="{{Greater color contrast ratio|black|white|black|css=y}}">Black</span> → Black

#005500

• <span style="background:#005500; color:{{Greater color contrast ratio|#005500|#FFFFFF|#000000}}">#005500</span> → #005500
• <span style="{{Greater color contrast ratio|#005500|#FFFFFF|#000000|css=y}}">#005500</span> → #005500
• <span style="background:#005500; color:#{{Greater color contrast ratio|005500|FFFFFF|000000}}">005500</span> → 005500
• <span style="{{Greater color contrast ratio|005500|FFFFFF|000000}}">005500</span> → 005500

CC5500

• <span style="background:#CC5500; color:#{{Greater color contrast ratio|CC5500|FFFFFF|000000}}">CC5500</span> → CC5500
• <span style="{{Greater color contrast ratio|CC5500|FFFFFF|000000|css=y}}">CC5500</span> → CC5500

CC5500, |bias=1

• <span style="background:#CC5500; color:#{{Greater color contrast ratio|CC5500|FFFFFF|000000|bias=1}}">CC5500</span> → CC5500
• <span style="{{Greater color contrast ratio|CC5500|FFFFFF|000000|bias=1|css=y}}">CC5500</span> → CC5500

error

• <span style="background:Not a color; color:#{{Greater color contrast ratio|Not a color|FFFFFF|000000}}">Not a color</span> → Not a color
• <span style="{{Greater color contrast ratio|Not a color|FFFFFF|000000|css=y}}">Not a color</span> → Not a color

(returns background-color:Not a color; color:;, and so no color is set; defaults to black-on-white.)

• <span style="{{Greater color contrast ratio|Navy|Not a color|000000|css=y}}">Not a color</span> → Not a color

(returns background-color:Navy; color:;, and so no fontcolor is set; defaults to black. The template did not function.)

See also

• {{Ensure AAA contrast ratio}}
• {{Ensure AA contrast ratio}}