save data in matrix after improfile

Hi,

I have an image and I would like to get a cross section of it- line intensity profile to evaluate the lines if are equally seperated . I had set improfile at the mid-point of the image and I got the intensity profile. After I would like to save the improfile matlab figure into a matrix and try get from the matrix a specific row for all the columns but I cant find the way to do it.

Please see my code below :

I = imread('Test-0.tif'); %% I have tif files but here I uploaded a jpg
x = [0 size(I,2)];
y = [size(I,1)/2 size(I,1)/2]; %choose the middle y data
improfile(I,x,y);

imshow(I);
figure
M=improfile(I,x,y);
save('data.mat','M');

[Geoff Hayes]

@Eva G are you observing an error with

[M(:,:)]=improfile(I,x,y);

? Why, on the left-hand side, are you using M(:,:) rather than just M?

[Eva G]

Sorry for the confusion . It was something that I was testing to find the issue . M=improfile (I,x,y) was initial code but it seems that it saves a matrix (2049x1) double and not a 2d matrix as it should.

[Geoff Hayes]

@Eva G - are you sure that the output should be sized differently? Maybe you need to capture the x and y coordinates as indicated here.

Answer 1

[Prachi Kulkarni]

Hi,

In the code snippet you have provided, the pixel values are sampled along only one line segment in image I. The endpoints of this line segment are I(0, size(I,1)/2) and I(size(I,2), size(I,1)/2). Hence, the output variable M is giving a single vector of pixel values along the segment.

To get the profile along multiple horizontal line segments in the image, you will have to generate the profile for all the line segments in a loop and combine their output in a matrix. For example, to get a profile along 3 horizontal lines at the top, middle and bottom, the code would be as follows.

I = imread('Test-0.jpg'); %% I have tif files but here I uploaded a jpg
x = [0 size(I,2)];
M = [];
for yi = [1 size(I,1)/2 size(I,1)]
    y = [yi yi]; %choose the middle y data
    figure
    Mi = improfile(I,x,y);
    M = [M ; Mi'];
end
save('data.mat','M');