Rotate individual labelled/segmented characters about its centroid

Question

Ronald Lim 2020-9-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591022-rotate-individual-labelled-segmented-characters-about-its-centroid

编辑： Ronald Lim 2021-1-10

采纳的回答： Madhav Thakker

在 MATLAB Online 中打开

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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Answer 1

Madhav Thakker 2020-9-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591022-rotate-individual-labelled-segmented-characters-about-its-centroid#answer_495547

在 MATLAB Online 中打开

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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Ronald Lim 2020-10-25

Attached was the image that was clipped off

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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