Finding connected pixels of an object from a starting pixel in a gray scale image

Please I need your help.

Is there anyone who can help me to find connected pixels of an object from a gray scale image. I mean what is the method that I can use? (i,e In each iteation, a region is grown from the start seed pixel. the growth of reagion spreads across all

connecting pixels that are not already labeled and that are above the current threshold Th)

Thanks in advance

Answer 1

[Matt J]

Once you threshold the image (making it binary) you can use regionprops or bwconncomp.

[Mary Ben]

Thank you for your replay. In fact I can use this solition for the whole of the image. But I want to extract firstly, for example juste the 1000 pixels from the starting pixels, not all objects in the image.

[Matt J]

I don't think you'll find that in Matlab proper. You can look through some of the region growing routines on the File Exchange to see if any give you that kind of control,

https://www.mathworks.com/matlabcentral/fileexchange/19084-region-growing?s_tid=srchtitle

[Mary Ben]

I tried with this code that you attached and I made some changes, but the problem is that the region grows on the side of the background and not from the object!!

Answer 2

[Matt J]

You could apply bwdist to find all pixels that are within some distance of the seed pixels, and bwdistgeodesic if you want to constrain that distance to certain paths.

[Mary Ben]

what you think about Flood-fill technique, it can be the solution ?

[Matt J]

With what Matlab tool? And would it let you capture only 1000 pixels worth of region growth?

[Mary Ben]

with matlab I dont have any idea... with the last code of region growing i can select juste 1000 pixels but after run I obtain a grown region of background not for object that I want to detect.