how to do the distance transform

2011 12 12
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Hi,all.I am processing a image. I need to do the distance transformation.This is my code:
myImage=imread('EarImage_1.tif');
I = rgb2gray(myImage);
whitePart = I > 220;
blackPart = I < 110;
imshow(whitePart);
I2=1-blackPart;
figure,imshow(I2);
D=bwdist(I2);
figure,imshow(~D);
This is my original picture:
After this process,I got an image just the same as "I2",which is the binary image before. I didn't get the picture as expected. I am a beginner of matlab. If anyone could tell me the solution of that, I would appreciate very much.
Thank you.

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Walter Roberson
Walter Roberson 2011-12-12
http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers

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Sean de Wolski
Sean de Wolski 2011-12-12

0 个投票

showing ~D means that only distances equal to zero (i.e. points that are true in I2) will be shown. D is an array of doubles.
imshow(D,[]);
will show you the distance xform image with the full range of values. Good job getting to where you are, +1.

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Yu Zhang
Yu Zhang 2011-12-13
Thank you very much! I got it. But the results look not good. I could not identify the kernel at all. Could you tell me whether I should do some other processes before the distance transform? I have done the median filter and get the gradient of the image. The gradient image looks good which is clear enough.Thank you!
Sean de Wolski
Sean de Wolski 2011-12-13
We need to see your image. Post it somewhere, perhaps to one of the websites in Walter's comment link and paste the url into your original question.

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Walter Roberson
Walter Roberson 2011-12-12

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Do not subtract blackPart from 1 if you want to see white pixels for the locations selected by blackPart.
1-(I<110) is the same as (I>=110) which could look very similar to (I>220) that you are already plotting. All of the (I>220) would be included within the (I>=110)

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