How to detect a dark color in RGB triplet?

4 visualizzazioni (ultimi 30 giorni)
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:

Risposta accettata

Image Analyst
Image Analyst il 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 Commenti
David Franco
David Franco il 26 Apr 2020
For Gama 0-1 should I use 0.5 instead of 128?
David Franco
David Franco il 26 Apr 2020
I am already using
if mean(color) < 0.45 % tried with median(color) < 0.45 too
mapshow(Snew(results(ii,2)),'FaceColor',color,'EdgeColor',[1,1,1]); % white border
else
mapshow(Snew(results(ii,2)),'FaceColor',color,'EdgeColor',[0,0,0]); % white border
end
But the results aren't good enough... Sometimes light regions get white borders:

Accedi per commentare.

Più risposte (0)

Prodotti


Release

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by