What should I do if the brightness of backgroud is very close to foreground?

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Dongyu Liang 2021-3-2

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评论： Dongyu Liang 2021-3-4

Hi,

I have some images that I want to segment. However, The the brightness of backgroud is very close to foreground in my images.

Here is a example,

The red circled object is what I want. But after trying different methods, this is what I got

Is there any suggestions to get a better result? These segmented images are used to be mask for 3D segmentation by using ‘activecontour’. Other images have similar problem. And as you can imagine, The 3D structure is much larger than what I want.

Thanks!

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Answer 1

Image Analyst 2021-3-3

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They don't look that close. Thresholding should work fairly well. Otherwise use SegNet deep learing if you need to identify triangular protuberances. Not sure what you want though. What you got looks OK to me. Why is it not? What do you need to measure from it. Tell me so I can know how important holes and shape are.

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Image Analyst 2021-3-3

在 MATLAB Online 中打开

I'd call imfill() then call bwboundaries(). Then pass the leftmost and rightmost coordinates (say the outer 10 columns or whatever) into polyfit() to get a parabola. Then use poly2mask() to get a mask of the parabola corner blob and use it to erase the original blob leaving only the triangle. Something like (untested)

mask = imfill(mask, 'holes);
mask = bwareafilt(mask, 1); % Take largest blob only.
% Get boundary
boundaries = bwboundaries(mask);
boundaries = boundaries{1};
x = boundaries(:, 2);
y = boundaries(:, 1);
% Determine leftmost and rightmost coordinates.
[rows, columns, numColors] = size(mask);
indexes = x < 10 | x > columns - 10;
% Fit a parabola
coefficients = polyfit(x(indexes), y(indexes), 2)
xFit = 1 : columns;
yFit = polyval(coefficients, xFit);
% Add bottom line
xFit = [1, xFit, columns, 1];
yFit = [rows, yFit, rows, rows];
parabolaMask = poly2mask(xFit, yFit, rows, columns);
% Get mask without parabola
mask(parabolaMask) = false;
imshow(mask);

Image Analyst 2021-3-4

I can't really explain it here. You're just going to have to go through some of the demos yourself and adapt them.

Dongyu Liang 2021-3-4

thanks!

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What should I do if the brightness of backgroud is very close to foreground?

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