Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: How to calculate the angle between two images?
Replies: 41   Last Post: Dec 8, 2012 11:02 PM

 Messages: [ Previous | Next ]
 Dave Robinson Posts: 1,338 Registered: 1/25/05
Re: How to calculate the angle between two images?
Posted: Apr 5, 2009 10:15 AM

"khoo" <jim_khoo@hotmail.com> wrote in message <grad5q\$cai\$1@fred.mathworks.com>...

> below is the function i try to convert the image to 1 Dimensional matric
> function b=transform(a)
>
> [row,column]=size(a);
> b=[];
>
> for i=1:row
> for j=1:column
> b=[b a(i,j)];
> end
> end

Why on earth are you trying to convert an image into a 1 dimensional vector? you are correlating 2 histograms - histograms are essentially graphs - in your case angle along the x axis, number of pixels of that angle in y direction. If you have say 256 angles, then each bin represents (2*pi)/256 radians. Thus the histogram will be a vector of 256 numbers, each number representing the number of pixels of that angle.

I suggest you carefully read help hist(), doesn't that default to 10 bins - you will need to have much better resolution than that.

I have had a look at your images, and would have thought they were ideally suited to this methodology.

Regards

Dave Robinson

Date Subject Author
4/3/09 khoo
4/3/09 Dave Robinson
4/3/09 khoo
4/3/09 Dave Robinson
4/3/09 khoo
4/3/09 Dave Robinson
4/3/09 khoo
4/3/09 khoo
4/4/09 khoo
4/4/09 Dave Robinson
4/4/09 khoo
4/4/09 khoo
4/5/09 khoo
4/5/09 Dave Robinson
4/5/09 khoo
4/5/09 khoo
4/5/09 Dave Robinson
4/5/09 khoo
4/6/09 khoo
4/6/09 Dave Robinson
4/6/09 khoo
4/6/09 Dave Robinson
4/6/09 khoo
4/6/09 Dave Robinson
4/6/09 khoo
4/6/09 khoo
4/6/09 khoo
4/7/09 khoo
4/7/09 khoo
4/7/09 Dave Robinson
12/8/12 Jeff
4/3/09 Skeptic
4/3/09 Dave Robinson
4/3/09 Roger Stafford
4/3/09 khoo
4/3/09 Roger Stafford
4/3/09 ImageAnalyst
4/3/09 khoo
4/4/09 khoo
4/6/09 Matt
4/6/09 khoo
4/6/09 Matt