MATLAB: Line detect the length of a pixel in image processing

image processingImage Processing Toolboxline detection

Hi, I have one image with a lot of vertical lines. I want to know number of lines and length of each of the lines. Please help me. Thanks

Best Answer

There are thousands of vertical lines there, if you call a vertical line a series of white pixels in a single column with no breaks in it. You can count them simply by labeling the image using 4-connectivity

[labeledImage, numberOfRegions] = bwlabel(binaryImage, 4);

Now, some of those white blobs may be horizontal, or rounded blobs, so you might want to call regionprops and check the PixelIdxList property to make sure all the pixels in each blob are in the same column. Use unique on the x (column) coordinates for that.

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MATLAB: Detecting thin edges of the connected cell

First call imfill() on your source image to get rid of internal black spaces:

filledImage = imfill(sourceImage, 'holes');

Then separate the blobs with watershed. For that see Steve's blog. Attach your code if you have any problems with Steve's algorithm.

MATLAB: Total area of a region of binary image

Huh? Of course you can use regionprops. No need to use bwboundaries() at all, unless you just want to show the outlines of the segmented areas in the overlay above your original gray scale or color image.

If you want the area of all the white pixels in your binary image you can do it two ways, with slightly different results because they use different calculation methods

pixelSum1 = bwarea(binaryImage);
pixelSum2 = sum(binaryImage(:));

If you want the area of each blob in the image individually, you can do it like this:

labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area];  % List of all the blob areas.
totalAreaOfAllBlobs = sum(allAreas); % Will be the same as pixelSum2

Best Answer

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MATLAB: Detecting thin edges of the connected cell

MATLAB: Total area of a region of binary image

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