How to convert an image to the cartesian X,Y coordinates?

90 views (last 30 days)
I have a grayscale image and i want to convert to the cartesian X,Y coordinates
  2 Comments
George
George on 19 Jun 2013
1 1 233
1 2 0
1 3 0
2 1 0
2 2 162
2 3 0
3 1 0
3 2 0
3 3 25

Sign in to comment.

Accepted Answer

Matt J
Matt J on 19 Jun 2013
Edited: Matt J on 19 Jun 2013
[x,y]=meshgrid(1:size(A,1), 1:size(A,2));
result=[x(:),y(:),A(:)];
  3 Comments

Sign in to comment.

More Answers (2)

Alex Taylor
Alex Taylor on 19 Jun 2013
Edited: John Kelly on 27 May 2014
If what you are trying to do is reference a 2-D image to a cartesian coordinate system, you should look at the class imref2d that ships with the Image Processing Toolbox as of R2013a
For example, if you want to reference the image A that Matt mentioned to the default (Intrinsic) coordinate system used by MATLAB in which the center of the first pixel is located at position (1,1) and each pixel has an extent of one unit, you could use the following syntax of imref2d:
A=diag(randi(255,1,3));
imref2d(size(A))
ans =
imref2d with properties:
XWorldLimits: [0.5000 3.5000]
YWorldLimits: [0.5000 3.5000]
ImageSize: [3 3]
PixelExtentInWorldX: 1
PixelExtentInWorldY: 1
ImageExtentInWorldX: 3
ImageExtentInWorldY: 3
XIntrinsicLimits: [0.5000 3.5000]
YIntrinsicLimits: [0.5000 3.5000]
imref2d also provides other construction syntaxes and writable properties if you want to reference your image to some other cartesian system.
imref2d provides various methods for converting two and from image subscripts and locations in a continuous cartesian system:
>> methods(imref2d)
Methods for class imref2d:
contains intrinsicToWorld worldToIntrinsic
imref2d sizesMatch worldToSubscript

Jeff E
Jeff E on 19 Jun 2013
Edited: Jeff E on 19 Jun 2013
Unimaginative solution below, possibly with extra computational overhead than a direct solution using reshape and some simple calculations for the X,Y cooridnates.
A=diag(randi(255,1,3))
A =
10 0 0
0 226 0
0 0 233
>> B = true(size(A))
B =
1 1 1
1 1 1
1 1 1
stats = regionprops(B, A, 'PixelValues' , 'PixelList');
PixelListValues = cat(2, [stats.PixelList] , [stats.PixelValues])
PixelListValues =
1 1 10
1 2 0
1 3 0
2 1 0
2 2 226
2 3 0
3 1 0
3 2 0
3 3 233
  1 Comment
George
George on 19 Jun 2013
A=imread('moon.tif');
B = true(size(A));
stats = regionprops(B, A, 'PixelValues' , 'PixelList');
PixelListValues = cat(2, [stats.PixelList] , [stats.PixelValues])
x,y counting stop to 255

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by