is there an alternative of thresholding an image automatically rather than setting it manually?

Question

bubble trouble 2011-12-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/24781-is-there-an-alternative-of-thresholding-an-image-automatically-rather-than-setting-it-manually

actually i am trying to implement a code that identifies just the round objects from an image referring http://www.mathworks.com/products/image/demos.html?file=/products/demos/shipping/images/ipexroundness.html , but the problem is that, every time for a new picture i have to change pixel value and threshold so that round objects are only visible and successfully identifies round objects rather than missing any... any alternative? or any guidence??

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Chandra Kurniawan 2011-12-27

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/24781-is-there-an-alternative-of-thresholding-an-image-automatically-rather-than-setting-it-manually#answer_32544

在 MATLAB Online 中打开

Actually function im2bw automatic select threshold value if

you do not pass any parameter except the input image.

Or try another option,, you can use graythresh if you consider not to setting the threshold value manually.

Eq:

J = im2bw(I, graythresh(I));

2 个评论
显示无隐藏无

bubble trouble 2011-12-27

ok will do that thanks a lot... do you have any idea as to how can i store the values in an array that are coming on the image specifically those that are greater than the threshold criteria?

Chandra Kurniawan 2011-12-27

Just use 'greater than' operator.

Eq :

threshold = 128;

I = imread('cameraman.tif');

J = I > threshold;

The array J stores all value that greater than threshold as 1

请先登录，再进行评论。

Answer 2

bubble trouble 2011-12-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/24781-is-there-an-alternative-of-thresholding-an-image-automatically-rather-than-setting-it-manually#answer_32546

% remove all object containing fewer than 30 pixels

bw = bwareaopen(bw,30);

now the above line is removing objects less than 30 pixels, this is specifically going to work for this picture, and if i do it with some other picture it fails to do it properly hope u are getting what im trying to sayyy....