Given a system (a website for instance) that lets a user customize the background color for some section but not the font color (to keep number of options to a minimum), is there a way to programmatically determine if a "light" or "dark" font color is necessary?
I'm sure there is some algorithm, but I don't know enough about colors, luminosity, etc to figure it out on my own.
I encountered similar problem. I had to find a good method of selecting contrastive font color to display text labels on colorscales/heatmaps. It had to be universal method and generated color had to be "good looking", which means that simple generating complementary color was not good solution - sometimes it generated strange, very intensive colors that were hard to watch and read.
After long hours of testing and trying to solve this problem, I found out that the best solution is to select white font for "dark" colors, and black font for "bright" colors.
Here's an example of function I am using in C#:
Color ContrastColor(Color color)
{
int d = 0;
// Counting the perceptive luminance - human eye favors green color...
double luminance = (0.299 * color.R + 0.587 * color.G + 0.114 * color.B)/255;
if (luminance > 0.5)
d = 0; // bright colors - black font
else
d = 255; // dark colors - white font
return Color.FromArgb(d, d, d);
}
This was tested for many various colorscales (rainbow, grayscale, heat, ice, and many others) and is the only "universal" method I found out.
Edit
Changed the formula of counting a to "perceptive luminance" - it really looks better! Already implemented it in my software, looks great.
Edit 2 @WebSeed provided a great working example of this algorithm: http://codepen.io/WebSeed/full/pvgqEq/