How can I track the boundary

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HUANG YU-CHE
HUANG YU-CHE on 29 Jun 2020
Commented: HUANG YU-CHE on 2 Jul 2020
I'm going to track the boundary line ,but my photo was not very clearly about some of the point(missing point),how can i set the missing point to NaN and replace
to Proximity value,to make the line complete ,thanks
fclose all; close all; clear all; clf; clc;
cd 'C:\Users\User\Documents\MATLAB\test1\carmer1\photo1'
a=imread('img350.png');
i2=im2double(a);
ihd=rgb2gray(i2);
cd 'C:\Users\User\Documents\MATLAB\test1\carmer1\mavg1'
b=imread('imavg1.png');
b=im2double(b);
c=ihd-b;
msim_crop = imadjust(c,[0 0.1],[0 1],1.);
msim_crop = uint8(msim_crop);
bw0 = im2bw( msim_crop,graythresh(msim_crop).*0.01 );%0.12
windsz = 7; %4
H2 = fspecial('average',windsz); )
averaged_bw1 = imfilter(bw0,H2,'replicate');
the photo will look like this
so how can i just track the white boundary only like

Accepted Answer

Image Analyst
Image Analyst on 29 Jun 2020
If you want to find the light blue boundary on the left, I'd scan row by row using find() to find the leftmost white pixel. Then I'd fit a sliding quadratic to it with sgolayfilt(). Then I'd subtract the fit from the actual to find the distance. Distances that are greater than some amount, I'd discard. You might be able to use rmoutliers() for that. Give it a try. Here's a start
[rows, columns] = size(binaryImage);
leftColumns = columns * ones(rows, 1);
for row = 1 : rows
thisRow = binaryImage(row, :);
col = find(thisRow, 1, 'first')
if ~isempty(col)
leftColumns(row) = col;
end
end
smoothedColumns = sgolayfilt(leftColumns, 21, 2);
diffs = abs(smoothedColumns - leftColumns);
plot(diffs, 'b-', 'LineWidth', 2);
etc.
  3 Comments
Image Analyst
Image Analyst on 29 Jun 2020
Sorry - I reversed the polynomial order and window width. It should be sgolayfilt(leftColumns, 2, 21) or some other number than 21. A bigger number gives more smoothing.
HUANG YU-CHE
HUANG YU-CHE on 2 Jul 2020
thank you very much

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