MATLAB: How to find pixel connect in column matlab

connected lineimage processingsum columnvalue

I have line picture. and I want to sum column.

if value in column connected same column 3 and 4. count 1

if is not connected -> plus

Ex. pic

pic = [
      0 0 0 0 1 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 0 1 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 1 0 0 0 0 0 0 0
      0 0 1 0 0 0 0 0 0 0
      0 1 0 0 0 0 0 0 0 0
      1 0 0 0 0 0 0 0 0 0]

result = 1 1 1 2 2 0 0 0 0 0

Thank you.

Best Answer

This will give you

result =

1 1 1 2 2 0 0 0 0 0

exactly as you wanted (in your current version of the question):

pic = [
      0 0 0 0 1 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 0 1 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 0 1 0 0 0 0 0 0
      0 0 1 0 0 0 0 0 0 0
      0 0 1 0 0 0 0 0 0 0
      0 1 0 0 0 0 0 0 0 0
      1 0 0 0 0 0 0 0 0 0]
[rows, columns] = size(pic);
for col = 1 : columns
	[~, result(col)] = bwlabel(pic(:, col))
end

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This function can set exactly the same pointers as explained in the documentation: See doc figure "pointers" . You cannot set the radius of the circle pointer.

If you want to choose the radius freely, you need to draw the circle by your own.

[EDITED] For creating a 32x32 pointer, see the "PointerShapeCData" point in the posted link.

CData = [ ...
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1; ...
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2; ...
  0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 2, 2, 0, 0; ...
  0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 0, 0; ...
  0, 0, 0, 0, 0, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0; ...
  1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
LUT   = [NaN, 1, 2];   % Transparent, black, white
Shape = LUT(CData + 1);
Shape = cat(2, Shape, fliplr(Shape));
Shape = cat(1, Shape, flipud(Shape));
figure('Pointer', 'custom', 'PointerShapeCData', Shape);

This is a circle with 32 pixels diameter with black pixels and a white circle inside. This is visible on light and dark images. If only the black circle is wanted, use: LUT = [NaN, 1, NaN]

Set the 'PointerShapeHotSpot' to [16, 16]. Note, that the center is not exactly at the midpoint of the circle. To get this create a circle with an odd number of pixels.

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Repeating your comment above for how you allocate opSet:

opSet = new double*[columns]; 
for (p=0; p<columns ; p++) 
opSet[p] = new double[rows];

Since you allocate it this way, it is NOT guaranteed to be contiguous in memory as you claim. What you have done is first allocate an array of row pointers, and then each row pointer gets allocated a row of memory and those rows are NOT required to be next to each other in memory. They might happen to be for a particular run, but they might not be for another run. This is not a good way to allocate a matrix. What you should be doing is allocate the entire matrix as one contiguous block, and then if you want row pointers you can set them to point as desired. e.g., something like this:

opSet = new double*[columns]; 
opSet[0] = new double[rows*columns];
for (p=1; p<columns ; p++) 
opSet[p] = opSet[p-1] + rows;

That way you are guaranteed that the matrix is contiguous in memory and you can reliably use memcpy etc to copy the entire contents at once by just using the address in opSet[0]. Also, it is easier to clean up since you only have to delete opSet[0] and opSet (i.e., you don't need a for loop to delete opSet[1] through opSet[columns-1] since they were not separately allocated).

On the memcpy side, be sure you are using the v->opSet()[0] address, not just v->opSet() as you show above. The first is the address of the double data, while the second is the address of the row pointer array (not what you want to copy).

For the number of bytes to copy, you also incorrectly use sizeof(v->getOpSet()), which will give you the size of a pointer (typically 4 or 8 depending on your system). You should be using something like v->getCols() * v->getRows() instead.

Best Answer

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