How to extract the blob of gray image ?

Dear All ,

I want to extract blob of this image then measure the maximum major length.

I try some method but is is not work.

here is my code:

clc

clear

X = imread('img.tif')

X = imadjust(X);

% Threshold image - manual threshold

BW = im2gray(X) > 0;

% Open mask with disk

radius = 3;

decomposition = 0;

se = strel('disk', radius, decomposition);

BW = imopen(BW, se);

% Close mask with disk

radius = 5;

decomposition = 0;

se = strel('disk', radius, decomposition);

BW = imclose(BW, se)*255;

% imshow(BW)

props = regionprops(BW,'MajorAxisLength','BoundingBox')

[max_length, idx] = max([props.MajorAxisLength]);

% Get the bounding box of the biggest blob

bbox = props(idx).BoundingBox;

% Plot the rectangle around the biggest blob

figure;

imshow(BW);

hold on;

rectangle('Position', bbox, 'EdgeColor', 'r', 'LineWidth', 2);

Thanks and Regards!

Han

Answer 1

[Image Analyst]

I'd try some denoising first, like medfilt2 or imnlmfilt. Then I'd try adjusting the thresholds with my interactive thresholding app:

https://www.mathworks.com/matlabcentral/fileexchange/29372-thresholding-an-image?s_tid=srchtitle

Then use bwferet. Don't use MaxAxisLength of regionprops since that gives you the max axis length of an ellipse fitted to the shape rather than the actual caliper distance like bwferet gives you.

[Jenifer NG]

Thanks you for your advice

I use the ImageSementer APP then app imcomplement then i can get the expected output by using bwferet .