How to detect a dark color in RGB triplet?
4 views (last 30 days)
Show older comments
David Franco
on 26 Apr 2020
Commented: David Franco
on 26 Apr 2020
I am plotting a map with many subdivision and colors.
I would like to automatically draw the borders with contrasting color with respect to the facecolor of the subdivision.
I am using the sum of the RGB triplet but I am not having perfect matchs.
Is there another way to do that?
My results until now:
0 Comments
Accepted Answer
Image Analyst
on 26 Apr 2020
I don't know what you do on the border between light and dark regions. But anyway, when you're drawing the boundary around a region get the mean RGB of that region -- summing the values is fine, or equvalently, taking the mean. Then you can say
meanRGB = mean([regionsRedValue, regionsGreenValue, regionsBlueValue]);
if meanRGB < 128
% It's dark, so draw with white line.
lineColor = 'w';
else
% It's bright, so draw black line.
lineColor = 'k';
end
plot(x, y, '-', 'Color', lineColor, 'LineWidth', 2);
2 Comments
More Answers (0)
See Also
Categories
Find more on Map Display in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!