sum pixel value in an image.
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Hi all,
I have a series of images in one dicom file (n =16 images). How can i find frames that contain maximum and minimum sum of pixel values (i.e. signals) and how to find their corresponding values (i.e. the sum of pixel values for the maximum frame and minimum frame) ?
the file is called MUGA.dcm
采纳的回答
Divya Yerraguntla
2019-9-23
Hi Ahmad,
Try using the following code to find the sum of pixels of images in DICOM file.
n=[];
% Find sum of images by providing your DICOM file name
for i=1:10
[X, map] = dicomread('DICOM filename','frames',i);
n = [n,sum(X(:))];
end
% Find maximum and minimum summation and indices.
[min, minidx] = min(n);
[max, maxidx] = max(n);
Hope it helps!
更多回答（3 个）
Divya Yerraguntla
2019-9-27
0 个投票
Hi Ahmad,
- Yes, the dicomread function returns the pixel values of the file and stores it in variable X in the above mentioned code.
- The variable maxidx in the above code gives the frame number which has the maximum pixel sum value and variable max gives the pixel sum of that frame.
- 'frames' indicates the frames to read, specified as an integer scalar, a vector of integers, or 'all'. When value of 'frames' is numeric, dicomread reads only the specified frame numbers from the image. By default, dicomread reads all frames of the DICOM image.
Hope it helps!
3 个评论
Ahmad Alenezi
2019-9-27
Divya Yerraguntla
2019-9-27
Could you provide MUCA.dcm file?
Ahmad Alenezi
2019-9-30
Divya Yerraguntla
2019-10-4
0 个投票
Hi Ahmad,
The code and file you have provided are giving the following results.
Are these the expected ones?
Ahmad Alenezi
2019-10-4
0 个投票
Hi Divya,
Yes, these results are the expected. Thanks indeed
One last question:
I know how to apply region of interest over a small part of the image (see image). This results in 128x128x16 uint 16 array (I call it ROI). How can I put ROI instead of dicomread('MUGA.dcm').?? meaning that i want my input to be ROI instead of MUGA.dcm
Best,
Ahmad
7 个评论
Image Analyst
2019-10-4
Do you want to just erase (make black) everything outside the mask and then process the image?
maskedImage ==grayImage
maskedImage(mask) = 0;
or do you want to just get a list of all pixels inside the mask in a 1-D list and do something with them?
pixelsInMask = grayImage(mask);
Ahmad Alenezi
2019-10-4
Subhadeep Koley
2019-11-3
You can use the roipoly() function to launch an interactive tool which can generate a binary mask for your ROI. When the polygon tool is active, using the mouse, you specify the region by selecting vertices of the polygon. You can move or resize the polygon using the mouse. When you are finished positioning and sizing the polygon, create the mask by double-clicking, or by right-clicking inside the region and selecting Create mask from the context menu.
Use the code below.
clear; close all; clc;
X = dicomread('MUGA1.dcm'); % Read your DICOM
temp = rescale(X(:,:,1)); % Select one frame from the mask generation
mask = roipoly(temp); % Specify polygon ROI with the interactive polygon selection tool
X_masked = zeros(size(X)); n = [];
for i=1:16
for j=1:128
for k=1:128
if(mask(j,k) == 1)
X_masked(j,k,i) = X(j,k,i);
n = [n,sum(X_masked(:))];
end
end
end
end
% Find maximum and minimum summation and indices.
[min, minidx] = min(n);
[max, maxidx] = max(n);
Hope this helps Ahmad!
Ahmad Alenezi
2019-11-4
Subhadeep Koley
2019-11-4
Ahmad, the code is running in my end without any error. I am using the the attached DICOM file.
Ahmad Alenezi
2019-11-4
Subhadeep Koley
2019-11-4
I think the DICOM file you are using has less than 16 channels.
However, please use the code below. It is more generalized and will work for DICOM files of any channel length.
clear;close all;clc;
X = rescale(squeeze(dicomread('MUGA1.dcm'))); % Read your DICOM
temp = rescale(X(:,:,1)); % Select one frame from the mask generation
mask = roipoly(temp); % Specify polygon ROI with the interactive polygon selection tool
X_masked = zeros(size(X)); n = [];
for i=1:size(X,3)
for j=1:128
for k=1:128
if(mask(j,k) == 1)
X_masked(j,k,i) = X(j,k,i);
n = [n,sum(X_masked(:))];
end
end
end
end
% Find maximum and minimum summation and indices.
[minVal, minIdx] = min(n);
[maxVal, maxIdx] = max(n);
Hope this helps!
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