I try to rotated my QR code depends on three boxs i used this code but didn't work

I = imread('2.1.bmp');
Igray = rgb2gray(I);;
BW = edge(Igray,'canny');
% We can see that the image is noisy. We will clean it up with a few
% morphological operations
Ibw = im2bw(Igray,graythresh(Igray)); 
se = strel('line',1,100);
cleanI = imdilate(~Ibw,se);
figure, imshow(cleanI);
%Perform a Hough Transform on the image 
% The Hough Transform identifies lines in an image 
[H,theta,rho] = hough(cleanI);
peaks  = houghpeaks(H,3);
lines = houghlines(Ibw,theta,rho,peaks);
% Highlight (by changing color) the lines found by MATLAB
hold on
for k = 1:numel(lines)
    x1 = lines(k).point1(1);
    y1 = lines(k).point1(2);
    x2 = lines(k).point2(1);
    y2 = lines(k).point2(2);
    plot([x1 x2],[y1 y2],'Color','g','LineWidth', 2)
end
hold off

% Identify the angles of the lines. 
% The following command shows the angle of the 2nd line found by the Hough
% Transform
lines(1).theta

ans = -45

lines(2).theta

ans = 45

lines(3).theta

ans = 45

%J = imrotate(cleanI,lines(1).theta,'bilinear','crop');
figure, imshow(J);

Unrecognized function or variable 'J'.

angle_1=lines(1).theta;
if lines(1).theta ~=45 
    J = imrotate(cleanI,45,'bilinear','crop');
    figure, imshow(J);
end

if lines(2).theta ~=-45 
    J = imrotate(cleanI,-45,'bilinear','crop');
    figure, imshow(J);
end

[Matt J]

I have edited your post and applied the run button to your code. As you can see, it doesn't run to completion so we cannot know what result you want us to see.

[S. M]

i wanna rotate image depend on three corners in QR code

[Matt J]

Your code shows

Unrecognized function or variable 'J'.

because J has not been defined

[Rik]

Comment posted as flag by @S. M:

okay ,but still image didn't rotate successfully

Answer 1

[yanqi liu]

clc; clear all; close all;
I = imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/848380/2.1.bmp');
Igray = rgb2gray(I);
BW = edge(Igray,'canny');
% We can see that the image is noisy. We will clean it up with a few
% morphological operations
Ibw = im2bw(Igray,graythresh(Igray)); 
se = strel('line',1,100);
cleanI = imdilate(~Ibw,se);
figure, imshow(cleanI);
%Perform a Hough Transform on the image 
% The Hough Transform identifies lines in an image 
cleanI2=bwperim(imclose(cleanI,strel('square',100)));
[H,theta,rho] = hough(cleanI2);
peaks  = houghpeaks(H,3);
lines = houghlines(Ibw,theta,rho,peaks);
% Highlight (by changing color) the lines found by MATLAB
hold on
for k = 1:numel(lines)
    x1 = lines(k).point1(1);
    y1 = lines(k).point1(2);
    x2 = lines(k).point2(1);
    y2 = lines(k).point2(2);
    plot([x1 x2],[y1 y2],'Color','g','LineWidth', 2)
end
hold off

% Identify the angles of the lines. 
% The following command shows the angle of the 2nd line found by the Hough
% Transform
lines(1).theta

ans = -63

lines(2).theta

ans = -63

lines(3).theta

ans = 27

J = imrotate(cleanI,lines(1).theta,'bilinear','crop');
J2 = imrotate(Igray,lines(1).theta,'bilinear','crop');
J3 = imdilate(J, strel('square', 9));
[r,c] = find(J3);
rect = [min(c) min(r) max(c)-min(c) max(r)-min(r)];
figure; imshow(J);
hold on; rectangle('position', rect, 'EdgeColor', 'g', 'LineWidth', 2)

qr_img = imcrop(J2, rect);
figure; imshow(qr_img);

then we can use zxing to decode，and use base64 to decode

%res = qr_code_extract(qr_img)
res = 'D8YAr0oOO6HusQQ61fNDKw=='

res = 'D8YAr0oOO6HusQQ61fNDKw=='

res2 = native2unicode(matlab.net.base64decode(res))

res2 = '� �J;��:��C+'

[S. M]

thank you , but how to put three corners in the top like this (normal QR)

[yanqi liu]

yes，sir，thie image can directly process，such as

clc; clear all; close all;
im = imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/849060/pic_1.png');
res = QrDen(im)
res2 = native2unicode(matlab.net.base64decode(res))

function res = QrDen(qr_im)
if nargin < 1
    load mtx.mat;
    qr_im = mtx;
end
zxingpath = fullfile(fileparts(mfilename('fullpath')), 'zxing_encrypt.jar');
javaaddpath(zxingpath);
zxingpath = fullfile(pwd, 'zxing_decrypt.jar');
javaaddpath(zxingpath);
qr_im = im2java(qr_im);
width = qr_im.getWidth();
height = qr_im.getHeight();
source = com.google.zxing.client.j2se.BufferedImageLuminanceSource(qr_im.getBufferedImage());
binarizer = com.google.zxing.common.HybridBinarizer(source);
bitmap = com.google.zxing.BinaryBitmap(binarizer);
reader = com.google.zxing.MultiFormatReader();
res = char(reader.decode(bitmap));
end

result is

res =

'D8YAr0oOO6HusQQ61fNDKw=='

>> res2 = native2unicode(matlab.net.base64decode(res))

res2 =