Is there a formula for deriving readable text for a color?

[TechBoyJK]

Is there a math formula that can be used to determine if text will be readable when placed on a background of another, given color?

Let's say I pick color with value #009900, is there a way to safely choose a color that can be placed on it that will be legible?

 

[alfa147x]

Yes




i

 

[rivan]

http://particletree.com/notebook/calculating-color-contrast-for-legible-text/

 

[Saint Nick]

Yes, it's called the complementary color. There are plenty of complementary color generators out there.

 

[Ben90]

if green value >= 128 set opposite green value to 0
if red value >= 128 set opposite red value to 0
if blue value >=128 set opposite blue value to 0

if green value < 128 set opposite green value to 255
if red value < 128 set opposite red value to 255
if blue value < 128 set opposite blue value to 255

works everytime