Visboundaries usage- red outline

hi i wrote this code

BW = imread('picture'.png)

B = bwboundaries(BW);

figure;

imshow(BW);

hold on;

visboundaries(B)

when i run this, the figure comes out and the boundaries show up but there is a red outline on the border of the image itself. how do i get rid of this line? I have attached a picture to show which line i mean

thank you very much!

Answer 1

[Image Analyst]

bwboundaries() is meant to work on a binary image, not a gray scale one. So, because you passed it a gray scale image, it took the white part as the foreground region and visboundaries() drew the boundaries around the white regions. To fix, try this

grayImage = imread('picture'.png)
BW = grayImage < 250; % or some value that works.

[Sang Wan Kim]

oh sorry about that! wrong picture. i did the bwboundaries on a binary image and i just showed it on the greyimage! i have attached a picture of it showing on the the binary image.

[Image Analyst]

Again, it's outlining the white areas because white is foreground. If you don't want that, then invert BW before you call bwboundaries(). See what I did. I took the dark areas, not the bright areas.

[Sang Wan Kim]

ah i see!! that makes sense.... Thank you very much

Answer 2

[hupaa san]

Hi, I run matlab example of 'activecontour' command on matlab version R2013a. but when I write 'visboundaries' command it show me this error:

Undefined function 'visboundaries' for input arguments of type 'char'.

and when I enter 'doc visboundaries' in command line window,there is no doc for 'visboundaries' in my matlab too. could u please guide me?

Thanks

[Image Analyst]

You can get it when you upgrade. It was introduced in R2015a. Please upgrade, or else use plot().