Comments on: Connected component labeling - Part 6

By: Steve

Steve — Fri, 24 Jul 2009 00:36:22 +0000

Anand—Connected-component labeling will probably be useful to you, but you don’t need to implement the algorithm yourself. Just use bwlabel (or bwconncomp if you already have the R2009a release) from the Image Processing Toolbox.

By: anand

anand — Tue, 21 Jul 2009 11:02:11 +0000

Hi,
I need to detect text (font) region in a image (a high resolution text imgae).. I just want to know , will this algo help me out?

thanks
Anand

By: Steve

Steve — Thu, 25 Jun 2009 15:03:36 +0000

Ardy—There is a lot information available online about the union find algorithm. I can also recommend Sedgewick, Algorithms in C, 3rd ed, Parts 1-4, pp. 10-23.

By: Ardy

Ardy — Thu, 25 Jun 2009 14:49:23 +0000

Hi, i would like to know more details about union find.

like in an image, may be:

note 1 can be connected to 2, 3, 5
note 2 can connect to 4, 6
note 3 can connect to 2, 6

how u put all the linked note together effectively?

By: Steve

Steve — Mon, 14 Jul 2008 12:49:43 +0000

Shannon—No, bwlabel and bwlabeln compute the connected components of pixels, not cells. If cells are touching in the output of your segmentation step, then bwlabel will consider them to be part of the same object. You can count background pixels in a binary image bw with something like this:

sum(~bw(:))

By: Shannon

Shannon — Mon, 14 Jul 2008 07:55:14 +0000

just to clarify, this can be used to represent cell connectivity, after you have segmented an image? like you have an image of red blood cells or something and want to figure out how many cells each cell is in contact with… bwlabeln will do it? this might just solve my problems.

and i’m also doing porosity of a foam. after i do bwlabel and segmentation and all that, how can i subtract the area of the cells (L, right?) from the “nothing” black background to get the dead space/air/pores?

if you can help or suggest any other code to help, that would be wonderful!

By: Steve

Steve — Mon, 07 Jul 2008 13:19:54 +0000

Jackey—See Algorithms in C by Sedgewick, 3rd edition, pp. 18–21.

By: Jackey

Jackey — Thu, 26 Jun 2008 15:47:59 +0000

hello man, i am chinese, i just want to know some detail about the algorithm of the path compression by halving in C,thanks!

By: Steve

Steve — Mon, 15 Oct 2007 15:29:57 +0000

Ashish—bwlabel scans image pixels columnwise, since that’s the way matrix elements are stored in memory. If you want a different order, you could transpose your matrix, or you could sort based on some other criterion. To sort by a different criterion, create a vector containing the values to be sorted, sort them and capture the 2nd output of the sort, and then use the 2nd output to rearrange your cell array.

By: Ashish Anant Saxena

Ashish Anant Saxena — Sat, 06 Oct 2007 16:08:44 +0000

correction in previous comment…….line 4th “one at the top right corner as the last component”