why does bwperim make the border WHITE?!!

2 次查看（过去 30 天）

显示更早的评论

Steven 2013-12-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/110646-why-does-bwperim-make-the-border-white

编辑： Steven 2014-1-1

采纳的回答： Image Analyst

在 MATLAB Online 中打开

I want to use bwperim to calculate the perimeter of an object, but I got a strange thing!

I use bwperim in two different states: first to the original binary image and second to its inverse, i.e.,:

%%binaryImage
perim1 = bwperim (binaryImage);
perim2 = bwperim (~binaryImage);

The strange thing is that the first one (perim1) gives an image that is almost black (except the detected boundaries, of course), but:

Exactly, the borders of the whole image, I mean the FIRST row and column and the LAST row and column are white! I mean it has given the value of 1 to the pixels of the image border! Why?!!

For the second one (perim2), this is not the case and it is correct as the original image.

The binary image:

perim1 (with white border):

perim2:

Thanks so much!

Steven

6 个评论
显示 4更早的评论隐藏 4更早的评论

Walter Roberson 2013-12-25

http://www.mathworks.com/help/images/ref/imclearborder.html

but be careful about the possibility that some of your image touches the border.

Steven 2013-12-25

for creating binary, I used:

binaryimage = im2bw(gray_scale_image,graythresh(gray_scale_image)

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Image Analyst 2013-12-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/110646-why-does-bwperim-make-the-border-white#answer_119297

I don't think perim1 should have the edges of the image as white. Can you post the binary image so I can check it out?

4 个评论
显示 2更早的评论隐藏 2更早的评论

Steven 2013-12-25

Thanks.

How about using imclearborder? It does the same right?

Thanks.

Steven

Walter Roberson 2013-12-25

Erasing the borders yourself is safer if you might possibly have an object touching the edge. If you know you will not, then imclearborder() is more convenient.

请先登录，再进行评论。