I want to calculate the white area of contour

"How can I calculate the white area of this contour?"

In my opinion, the number of white pixels corresponds to the white area I think.

If it is right, could you explain that how to count the number of white pixels.

Or do you have any other idea to calculate the area, please let me know.

thank you.

Here is m-file that creates contour.

clear;

clf;

clc;

filename = 'project.txt';

datatable = load(filename);

data = datatable(2:end,2:end);

length = datatable(1,2:end);

time = datatable(2:end,1).';

datasize=size(data);

row=datasize(1,1);

column=datasize(1,2);

row=1:row;

[c,h]=contourf(length,row',data,[20 2 30]);

colormap gray

grid on

hold on

Answer 1

[Image Analyst]

I don't have your data file so I can't run your code. But it looks like a gray image with the white being 255 so the usual code for that is

whitePixels = grayImage == 255; % A logical (binary) image
numberOfWhitePixels = sum(whitePixels(:));

[Jeong]

thank you very munch.

And I have one more question.

In this case, should I make a JPEG file from the contour to run your code?

or is it possible calulate the number of white pixels from contour directly?

In this adress, there is 'project.txt'file that you can run.

http://cyhome.cyworld.com/?home_id=a4151667

[Image Analyst]

My code just operates off the image, like the one you are showing. I don't care what format the image was stored it. It might have been JPG, PNG, BMP, TIFF, or whatever. That doesn't matter. All that matters is the image after you've read it in from disk. If you have the x,y coordinates of some contour line(s) then of course you can get the value of the image at those locations.

[Jeong]

So once I have to save contour image as JPG,PNG,BMP,TIFF before running your code by using a mouse since I'm a beginner.

If you know a code that can save contour image directly, please let me know.

Thanks for your kind reply.

[Image Analyst]

You can try export_fig - see the first page of the File Exchange. It's always the top download.

[Jeong]

Thanks a lot!