How to get level values by X Y coordinates from a contour plot?

Hi everyone, I have a image which name is Image1, then I used the contour function with contour(double(Image1)); after which I get a 2-D contour plot. Then is it feasible if I want to get the level values of the contour plot with x coordinate from ,say 100 to 200 when corresponding y coordinate from 100 to 200. Breifly speaking, is it feasible that I want to get the level values of that 10000 points from contour plot(100*100). If so, how? Thanks

[Walter Roberson]

Is the question about finding out what level values were using in a contour plot, or is the question about getting contour() to use particular level values that you specify?

[Jiafeng Ye]

Hi Walter, thanks for your reply. When I used the contour function, I got a contour figure from matlab. Then if I use datatip function,I can get points values as (X,Y and Level) for points, thus my question is that how can I get the level values corresponding to their X Y co-ordinates. For instance, if set X from 100,101,102 to 200, Y also from 100,101,102 to 200. I want to get the level values for these 10000 points. Is it feasible?if so what is the function used? I tried some functions such as getContourLineCoordinates, contourdata, but they didn't work as what I try to get.Thanks.

[Walter Roberson]

Are you using custom levels or letting it pick the levels?

[Jiafeng Ye]

I just used a photo as image, then turn it into black-white mode for the contour, the level values on the plot is dependent on the pixel value of the photo.

[Jiafeng Ye]

Now I consider to draw a grid on the contour plot and get the values of grid points.

Answer 1

[KSSV]

Read the documentation of contour..there is option of getting level values fromt he function.

[M,c] = contour(X,Y,Z) ;