Rotate individual labelled/segmented characters about its centroid

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Ronald Lim
Ronald Lim 2020-9-9
编辑： Ronald Lim 2021-1-10
Hi ,
How do I rotate the individual characters anti-clockwise 90 degrees about their own centroid?
I have obtained their centroids and other stuff:
Character # Mean Intensity Centroid(X) Centroid(Y) Area
# 1 54.8 16.7 57.6 109.0
# 2 62.8 33.5 57.6 136.0
# 3 79.5 51.5 57.3 106.0
# 4 66.1 59.9 28.1 145.0
# 5 62.4 68.1 56.7 100.0
# 6 65.6 77.2 29.0 100.0
# 7 55.4 85.6 55.2 56.0
# 8 55.5 94.9 26.0 50.0
# 9 67.3 100.2 56.9 118.0
#10 76.5 118.1 27.0 117.0
#11 65.7 116.6 56.4 118.0
#12 71.1 132.8 25.8 139.0
#13 59.9 130.7 53.2 102.0
#14 81.9 150.1 55.5 115.0
Things I have tried:
1.) tried cropping and rotate but could not crop individual characters and rotate
2.) Tried using BW2 = bwareafilt(BW,range) and rotate but the character rotate about the image centroid instead
3.) Wanted to tried bounded box but do not know how to write those codes
My codes
clear all;
I=imread('charact2.jpg');
J=imrotate(I,-180);
%Upright image
subplot(3, 3, 1);
imshow(J);
% Convert to binary image
J = im2bw(J,0.34);
%Remove symbol (row,column), convert to 1
J(6:42,7:41)=0;
subplot(3, 3, 2);
imshow(J)
% Identify each character by seeing which pixels are connected to each other.
labeledImage = bwlabel(J,8);
coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle');
subplot(3, 3, 3);
imshow(coloredLabels)
% Get all the char properties.
Measurements = regionprops(labeledImage,J,'all');
numberOfchar = size(Measurements, 1);
%get the centroids of ALL the char
fprintf(1,'Character # Mean Intensity Centroid(X) Centroid(Y) Area\n')
for k = 1 : numberOfchar
xCenter = Measurements(k).Centroid(1);
yCenter = Measurements(k).Centroid(2);
Pixels = Measurements(k).PixelIdxList;
Intensity = mean(I(Pixels));
CharArea = Measurements(k).Area;
charOrientation = Measurements(k).Orientation;
fprintf(1,'#%2d %18.1f %13.1f %12.1f %12.1f\n', k,Intensity, xCenter, yCenter, CharArea);
end

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采纳的回答

Madhav Thakker
Madhav Thakker 2020-9-16
Hi Ronald,
I understand that you want to rotate the letters 90 degrees anticlockwise. You are correct about extracting bounding boxes. You can extract bounding boxes, rotate them, and paste them on a new image.
I am attaching a snippet that can help you.
another = zeros(size(J));
for k =1:numberOfchar
croppedImage = imcrop(J, Measurements(k).BoundingBox);
angle = 90;
rotated = imrotate(croppedImage, angle);
center_x = Measurements(k).Centroid(1);
center_y = Measurements(k).Centroid(2);
[rows, cols] = size(croppedImage);
prev_x = round(center_y - cols/2);
prev_y = round(center_x - rows/2);
another(prev_x:prev_x+cols-1,prev_y:prev_y+rows-1) = rotated;
end
imshow(another)
Hope this helps.
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Image Analyst
Image Analyst 2020-10-25
编辑：Image Analyst 2020-10-25
You forgot to attach your m-file. Also since some characters are taller than wide, if you rotate them in place, the characters would be overlapped. Why do you want to do that? Why not just crop each character out to its own subimage to deal with it?

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