How to count the number of pixels of a certain color in an image?
65 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
MathWorks Support Team
am 10 Sep. 2018
Beantwortet: MathWorks Support Team
am 14 Mai 2019
I have an image and I want to count the number of red pixels in an image. How do I do that?
Akzeptierte Antwort
MathWorks Support Team
am 15 Mai 2019
You can use logical indexing with the matrix of RGB values to determine which pixels are red. A "pure" red will have RGB value (255,0,0), but a red color may be considered within a range around that. To help illustrate, refer to the example code below. Note that you may need to tweak the precise pixel intensity thresholds for each channel, as per your application-specific requirements and approximated range for what is considered red and what is not.
%%Load image
rgb = imread('peppers.png');
figure(1)
imshow(rgb)
%%Find red points
redPoints = rgb(:,:,1)>=130 & rgb(:,:,2)<=60 & rgb(:,:,3)<=100;
percentRed = 100*(sum(sum(redPoints))/(size(rgb,1)*size(rgb,2)));
fprintf('Image has %d red pixels\n',sum(sum(redPoints)))
fprintf('Image is %.2f percent red\n',percentRed)
%%Highlight red on image
rgbRed = uint8(cat(3,redPoints,redPoints,redPoints)).*rgb;
figure(2)
imshow(rgbRed)
0 Kommentare
Weitere Antworten (0)
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!