How to detect corner in rectangle?

Hi, i'm new in matlab image processing. As we know, the rectangle has 4 corner A,B,C,D. How to detect every corner in rectangle automatically? it's like :

if (corner was in A) then
do..
end
if (corner was in B) then
do..
end
if (corner was in C) then
do..
end
if (corner was in D) then
do..
end

please help me..thank in advance

Best Regards,

Answer 1

[Image Analyst]

I don't know what you want to do. Did you use the corner() function in the Image Processing Toolbox to detect your corners? Okay, let's say you did. Then do you look at all the points that are returned and determine which is A, which is B, etc.? I assume you did. But I don't know what you want to do inside the if blocks.

[Lily]

actually, it's so hard to explain what i mean here. i've made some codes with two function. but it have to be attached, it's like an email. so, do you mind if i ask you more in your email? please help me.. thank in advance

[Image Analyst]

We don't do offline private consulting here. Here are options for uploading files: http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers

[Lily]

okay,let me ask about the corner. How about this error? i take it from http://www.mathworks.com/help/images/ref/corner.html

I = checkerboard(50,2,2);
C = corner(I);
imshow(I);
hold on
plot(C(:,1), C(:,2), 'r*');
??? Undefined function or method 'corner' for
input arguments of type 'double'.

[Image Analyst]

Do "which corner" to see if you have it. It's fairly new, just introduced around a couple of years ago. You probably need to upgrade your version of MATLAB.

[Walter Roberson]

Alternately, Lily might not have the Image Processing toolbox installed or perhaps installed but not licensed. If she is using Student Version then she might not have gone back and installed it from her installation CD.

[Walter Roberson]

corner was introduced in R2010b. The release notes for that version say

In R2008b and later releases, you could find corners by computing a cornermetric matrix with the cornermetric function and then finding peak values. Now, you can simplify your workflow by using the corner function.