Re: Deciding whether text should be black or white for a given background color
Re: Deciding whether text should be black or white for a given background color
- Subject: Re: Deciding whether text should be black or white for a given background color
- From: Gregory Weston <email@hidden>
- Date: Mon, 4 Dec 2006 16:59:26 -0500
On Dec 4, 2006, at 4:10 PM, Ricky Sharp wrote:
On Monday, December 04, 2006, at 01:06PM, "Gregory Weston"
<email@hidden> wrote:
On Dec 4, 2006, at 1:57 PM, Keith Blount wrote:
The problem is, how do I programmatically decide what is a light-
and what is a dark-coloured background using methods available to
NSColor? Is there a well-known algorithm for deciding this?
You might try the math used in this sample code as a starting point.
<http://developer.apple.com/samplecode/Monochrome_Image/index.html>
The most interesting line for you, I'd think, is from
NSImage_monochrome.m
thisPixel->grayValue = rint(255 *
(0.299 * [pixelColor redComponent]
+ 0.587 * [pixelColor greenComponent]
+ 0.114 * [pixelColor blueComponent]));
This is the NTSC weighted algorithm. I know it works very well
(use it in my own app for grayscale conversions). Not sure how it
will stack up for the original poster's problem, but it's
definitely worth a shot to compare such results with the standard
brightness computation.
I probably should have clarified my intent in pointing that out to
the OP. My thought was that he could use that to determine the grey
level of the background and then arbitrarily pick some level at which
he should switch from black text to white.
Greg
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