How can I find maximums in the intensity profile and display it in the original image ?

Question

MMSAAH 2019-9-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/480235-how-can-i-find-maximums-in-the-intensity-profile-and-display-it-in-the-original-image

评论： darova 2019-9-17

采纳的回答： darova

sss.png

在 MATLAB Online 中打开

I have ('liftingbody.png') image and I want to display the intensity profile along a white curve ('sss.png').

I searched the coordinates of the white curve and I displayed the intensity profile of the ('liftingbody.png') along those coordinates.

After that, I searched the maximums in the c profile and I displayed it in the fused image.

My problem is why I got points outside the red curve ? here is my code.

Could anyone help me solving this problem ?

clear all, close all; clc
I2 = imread('liftingbody.png');
figure
imshow(I2);
I=imread('sss.png');
figure
imshow(I);
[x2,y2]=find (I>0);  % find the coordinates of white line
[cx,cy,c]=improfile(I2, x2,y2);  % display the intensity profile.(cx,xy):coordinates of intensity profile
% [pks,locs] = findpeaks(c);
[pks,locs] = findpeaks(c,'MinPeakDistance',50); % search maximums
figure
plot(c)
% display the curve in red
I = uint8(I);
[x,y,z]=size(I);
 for i=1:x
     for j=1:y
         if (I(i,j)==1)
             I(i,j,1)=255;
             I(i,j,2)=0;
             I(i,j,3)=0;
         end
     end
 end
figure
imshow(I);
title('red curve');
I  = imfuse(I, I2,'blend','Scaling','joint');
figure
imshow(I);
hold on
plot(cy(locs(:)),cx(locs(:)),'b*')

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darova 2019-9-13

Works ok for me

MMSAAH 2019-9-13

thank you for your answer but if you zoom in the picture even more, you will see many points outside the red curve.

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Answer 1

darova 2019-9-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/480235-how-can-i-find-maximums-in-the-intensity-profile-and-display-it-in-the-original-image#answer_392130

在 MATLAB Online 中打开

improf1.m

I think the problem is in order of points. MAthworks help:

improfile

Pixel-value cross-sections along line segments

Try this

I=imread('sss.png');
[x2,y2] = find (I>0);  % find the coordinates of white line
figure
imshow(I);
hold on
for i = 1:10:length(x2)
    plot(y2(i),x2(i),'.r')
    pause(0.1)
end
hold off

And now add this before plot()

[x2 ,ix] = sort(x2);   % sort vertically
y2 = y2(ix);

So i divided white line into two parts. Sorted top part vertically and bottom part horizontally

See attached script

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MMSAAH 2019-9-17

Thank you very much. This did solve my problem. I'm really grateful.

The problem was in fact related to the order of points

Could you explain me more please ? How did the sort () command solve the problem ?

Thanks a lot.

darova 2019-9-17

Imagine you have six pixels. You want to find (rows,columns) (position) of them

So order of pixels would be as i marked on the picture

Arrows indicate direction of search

So when you have some curve (marked black) and points (red) you have to find improfile

Blue lines will be the actual path of profile

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Answer 2

KALYAN ACHARJYA 2019-9-13

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/480235-how-can-i-find-maximums-in-the-intensity-profile-and-display-it-in-the-original-image#answer_391744

编辑：KALYAN ACHARJYA 2019-9-13

在 MATLAB Online 中打开

My problem is why I got points outside the red curve ? here is my code?

scatter(cy(locs(:)),cx(locs(:)),'b')

I dot think there are any points positioning the outside the Marker line (white line turned red line), use other plot way and see the results.

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KALYAN ACHARJYA 2019-9-13

May be there are few white pixels, just near the boundary. When I executed the code, all points are lie on the white line (as showed result)...again trying to visulize the plot.

MMSAAH 2019-9-14