UIColor - How can I convert to grayscale?

[me0007]

Is there any simple way to convert an RGB UIColor to a grayscale 'color'?

Thanks in advance!

[Duncan C]

Originally Posted by me0007

Is there any simple way to convert an RGB UIColor to a grayscale 'color'?

Thanks in advance!

You need to convert to a luminance value. I found this on Stack Overflow with a quick Google search:


Luminance (standard, objective): (0.2126*R) + (0.7152*G) + (0.0722*B)
Luminance (perceived option 1): (0.299*R + 0.587*G + 0.114*B)
Luminance (perceived option 2, slower to calculate): sqrt( 0.241*R^2 + 0.691*G^2 + 0.068*B^2 )


The bottom 2 are probably the best choices.


Or this one:



You'd then just set the r,g, and b values to that amount.

If you're working with 0-255 values, convert them to floats first (value/255), then convert the result back to a 0-255 value by multiplying it by 255.

[me0007]

Thanks, Duncan. I also googled, but obviously missed that one... I'll try and see how that works.

Steve