how bwlabel determine each unique label for each object in image ?

i have image

how bwlabel determine each unique label for labeling each object in this image ? how bwlabel select objects to be labeled 1 or 2 or 3 etc ? whether the unique label choose with random ?? thanks

Answer 1

[Image Analyst]

Starting at the upper left pixel, it goes down rows until it hits a new, unlabeled object. Then it labels all the pixels in it. Then it continues going down rows, and moving over columns until it has found all of the blobs. So the numbers are going from top to bottom and left to right, NOT left to right and top to bottom like you'd read a book.

[ElizabethR]

thank yo for answare my question. ohh, i see.. Thank you so much for your explanation. God Bless :)

[Image Analyst]

You're welcome - thanks for accepting. Sometimes the confusion comes about, for example in your image -- you'd think the upper left blob should be #1. However if it started in column 75 but the blob below it started in column 74, then the one below it is slightly to the left of the one in the upper left, and so it would get detected first and be labeled #1. Then the one in the upper left would be #2 and the one in the lower left would be #3.

[ElizabethR]

yes you are right, I had experienced problems like that.So it make me confused how to bwlabel labeled each object in image. But, thank you so much for your explanation. Now I have understoodv how bwlabel work. Once again thank you so much. God Bless :)