Thread Subject: All points in an area of an image

Is there any function in MATLAB that can import all points
(into a matrix, for eg) of a certain area in an image, be
it circle, be it rectangle as long as I have the specifics
of the bounding area....for example, if I have the centre
and radius of a circle in the image, can we go

function(xcentre, ycentre, radius) in image
I=imread('example.jpg')?

"Vivian Harvey" <viv_harv@yahoo.co.uk> wrote in message
<g0bs60$i81$1@fred.mathworks.com>...
> Is there any function in MATLAB that can import all points
> (into a matrix, for eg) of a certain area in an image, be
> it circle, be it rectangle as long as I have the specifics
> of the bounding area....for example, if I have the centre
> and radius of a circle in the image, can we go
>

This creates a new image with only the points
inside a circle of the old image.


I=load ('clown')


 image(I.X)
 colormap(I.map)


figure

 [x,y]=ndgrid([1:size(I.X,1)],[1:size(I.X,2)]);
 I.Z=I.X(((x-150).^2+(y-100).^2)<50^2);

 i=(((x-150).^2+(y-100).^2)<50^2);
 Z=zeros(size(I.X));
 Z(i)=X(i);
image(Z)
colormap(I.map)


if you want just the points, in an array:

Z=I.X(i);
X=x(i);
Y=y(i);

On May 13, 6:57=A0am, "Vivian Harvey" <viv_h...@yahoo.co.uk> wrote:
> Is there any function in MATLAB that can import all points
> (into a matrix, for eg) of =A0a certain area in an image, be
> it circle, be it rectangle as long as I have the specifics
> of the bounding area....for example, if I have the centre
> and radius of a circle in the image, can we go
>
> function(xcentre, ycentre, radius) in image
> I=3Dimread('example.jpg')?

----------------------------------
Vivian:
First you read the image into a 2D array (if it's monochrome) or a 3D
array if it's RGB color or multispectral. Then you can create a mask
of any shape you want and multiply it by your image to get an image
with just the pixels you want. Keep in mind that this will still be a
2D or 3D image that will just have zeros outside your mask. This is
because arrays have to be rectangular. If you want ONLY the pixels in
the mask, there are ways of pulling only those pixels out and
stringing them into one long 1D array. Which way were you thinking
of?
Regards,
ImageAnalyst