How to unwrap the circle?

[Umme Tania]

From this image i want to unwrap the gray part...so that i can represent this(pixel information) as a rectangle.

[Walter Roberson]

I am not sure what you mean by "unwrap" ? Are you wanting to project from the circle to a rectangle, interpolating to form a rectangular image like from stretching a sheet?

[Umme Tania]

yes

Answer 1

[Alex Taylor]

Use a polar transformation with the center of the transformation set to the center of the circle (roughly [161, 172]).

I like Peter Kovesi's implementation of the polar transformation:

http://www.csse.uwa.edu.au/~pk/research/matlabfns/Misc/polartrans.m

a = imread('http://www.mathworks.com/matlabcentral/answers/uploaded_files/482/crop_image.jpg');
out = polartrans(a,500,500,161,172,'linear','valid');
imshow(out);

[Umme Tania]

Thank you

Answer 2

[ramsha]

how to run this file ?

[Image Analyst]

What file? Whatever file it is, can't you just click the green triangle? Or type the name of it into the command window?