Find X and Y coordinates of white pixels in a grayscale image

Hi, I want to find the x and y coordinates of all the pixels corresponding to the white pixels in this image and store them in an array. Later I want to find the equation of the best fitting curve passing through these coordinates. Can someone please help me with how this can be done?

PS I am very new to MATLAB and programming in general.

Thank you in advance

Answer 1

[Matt J]

You will first need to get rid of the horizontal line of white pixels near the top,

load Image

Image(1:20,:)=0; Image=bwpropfilt(Image>0,'ConvexArea',1);  %Image cleanup

[y,x]=find(Image); %Get coordinates

plot(x,y,'x')

[Aditya Chivate]

Hi Matt J,

Thank you for your quick response. I got rid of the horizontal line of the white pixels near the top by cropping the image, but do you have any suggestions to do that without manually cropping the image?

The reason I am asking this is because I want to run a video showing dynamic growing of a shape, detect the edges, find the coordinates of the edges and fit a curve for each frame. Later I want to compare it against some simulations. This image is much cleaner, but some of the images that I have are a bit noisy. For instance the image below I just want to fit a curve in the dome shape

[Matt J]

but do you have any suggestions to do that without manually cropping the image?

My posted answer did so without cropping. I used masking instead.

This image is much cleaner, but some of the images that I have are a bit noisy.

You could probably apply strong smoothing to the image, e.g. imgaussfilt seeing as the thing you are trying to detect is relatively large.

[Aditya Chivate]

Thanks for the suggestion. I'll give a try on this

[Matt J]

You're welcome, but if your posted question (about finding X,Y) has been answered, kindly Accept-click.