MATLAB: How to extract a region of white pixel bounded by black pixel from white background

extraction of white pixel bounded by black pixelImage Processing Toolboxregion of interst detection

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It looks like a binary image. If it is, call imclearborder

binaryImage = imclearborder(binaryImage);

This will get rid of all white/1/true regions touching the edge of the image.

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MATLAB: Create narrow band of pixels under gray region

Threshold for black.

mask = grayImage == 0;

Extract the two largest regions

mask = bwareafilt(mask, 2);

Then find the centroid or bounding box

props = regionprops(mask, 'Centroid');

and extract the lower black region. See if you can do this yourself.

Call imerode() to shrink it. Then XOR the shrunken region with the original region to get just the edges.

mask = imerode(lowerMask, true(9)); % Increase from 9 to get a wider white region.
mask = xor(mask, lowerMask);

Then set those pixels in the original image to white:

grayImage(mask) = 255;

MATLAB: Black and white image

Try this

[counts, grayLevels] = imhist(grayImage, 256);
if sum(counts(2:end-1)) > 0
  % It's not pure black and white
end
% Get map of non-0 and non-255 pixels
grayPixels = grayImage > 0 & grayImage < 255;
% Get pure black and white image
bw = grayImage; % Initialize

bw(grayPixels) = 0; % Zero out any gray pixels.
% Get gray pixels only
grayOnly = grayImage; % Initialize
grayOnly(~grayPixels) = 0; % Zero out any pure 0 or pure 255 pixels.

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Related Solutions

MATLAB: Create narrow band of pixels under gray region

MATLAB: Black and white image

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