How to use threshold in this problem?
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I convert this picture into bw using c=im2bw(b,graythresh(b)); but the problem is the straight line is disconnected as picture below. It supposed to be straight single line. What kind of segmentation technique that I need to use?
采纳的回答
Alessandro Masullo
2015-1-23
Supposed your image varies from o to 1, you could use a threshold in this way:
THR = 0.5
above = image>=THR;
image(above) = 1;
image(~above) = 0;
6 个评论
muhammad ismail
2015-1-23
编辑：muhammad ismail
2015-1-23
Alessandro Masullo
2015-1-23
a=imread('S2a.jpg');
b= imcrop(a,[83 48 550 353]);
c = im2double(b);
THR = 0.5
above = c>=THR;
c(above) = 1;
c(~above) = 0;
muhammad ismail
2015-1-23
But it display like picture below. a=imread('S2a.jpg');
b= imcrop(a,[83 48 550 353]);
c = im2double(b);
THR = 0.5;
above = c>=THR;
c(above) = 1;
c(~above) = 0;
imshow(c);
Alessandro Masullo
2015-1-23
That's because your line gray level is the same of the background, so you cannot use a simple conversion from gray to b/w, but you have to use an edge detection algorithm, as Image Analyst suggested:
muhammad ismail
2015-1-23
编辑：muhammad ismail
2015-1-23
Alessandro Masullo
2015-1-23
I just used imagesc(c). You can use different colormaps instead of the grey levels, use:
colormap jet
help colormap
更多回答（1 个）
Image Analyst
2015-1-23
0 个投票
Like I said in your duplicate post, you can use imclearborder() and bwareaopen(), though there are better ways like background correction.
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