x,y coordinates in .txt to points on image

Hi there,

I need some help with loading coordinates in a .txt to points in an image. In the attached .txt are all the coordinates. What is the best approache to do this?

thanks,

[Scott MacKenzie]

What do you mean by "to points in an image"? The x-y coordinates are in the range -10 to +10 (approximately), so if you intend to map them to an image (e.g., 1000x2000), then some scaling will be necessary. Explain your objective, if you can, please.

Answer 1

[Adam Danz]

1. Read in the file using A = readmatrix(filename)
2. Plot the values using the plot command where x is the first column of A and y is the second column of A. Use indexing A(:,i)

[Image Analyst]

And make sure you scale the (x,y) values

[rows, columns, numColors] = size(yourImage);
imshow(yourImage);
impixelinfo;
x = rescale(A(:, 1), 1, columns);
y = rescale(A(:, 2), 1, rows); % Or however you need to do it.

and make sure you call

hold on;

after you call imshow() but before you call plot() or else the plot will blow away your image.

And remember images are indexed (row, column) which is (y, x) -- not (x,y) like plot() uses. So don't call yourImage(x, y) and expect that the gray level will match the gray level under that coordinate. You'd need to use yourImage(y, x).