Sorting points of image

I have an image with white curves on black background. How to Sort the white pixels in an array? the pixel array is attached.Thanks in advance.

[KSSV]

I think they are alredy wll sorted......what you are expecting?

[JRose]

ther are not sorted continuously. normally it will be sorted in the way the image is read by matlab. i need it to be sorted along the curves as it is drawn.

[Jan]

So you want to find a start point at one of the ends and determine the nearest neighbor iteratively?

[JRose]

Yes.. iteratively i wish to sort the points from the left end th the right end of this curve. the x and y coordinates are given in the array.txt. Your help will be appreciated. Thank you.

[Jan]

Now please explain, if this is the only case, or if you have a set of diffente input data, which might be less clear. "Left end" need not necessarily unique. Do you want to select it manually with the mouse or automatically?

[JRose]

@Jan No sir. This is not the only case. I just need a general program to collect all the connecting white points in any image in a continuous manner in any direction just like tracing the structure. Not with the use of mouse. Just to sort the pixel coordinates from the binary image. For closed structures it's easy. But for curves and lines with different angle, I couldn't find a solution.

[Jan]

@JRose: The question is still not clear. Now you mention "sort the pixel coordinates from the binary image", but formerly it lookewd like you do have the corrdinates already. In the posted screenshot you do not have single points, but an area with several points beside eachother, about 8 or 10.

Please explain uniquely, what your inputs are and what you want to achieve.

[JRose]

if we plot the lines it matches excatly. what i need is to get the points in an ordered manner. if the coordinate of white pixel on th eleft most end is 1st element of the array, the i need the send element as the nearest white pixel and so on. i have pllotted the points after saving it to array from the image and got excatly what you sai. but i couldn't get it as i mentioned above. my purpose is to take a line profile along these edges of the coordinate. thats why i need it in an ordered manner. please correct me if i'm wrong

[Jan]

@JRose: I do not understand, what "if we plot the lines it matches excatly" means. "a line profile along these edges of the coordinate" is not clear to me also.

You do not answer my question, what exactly your inputs are. A screenshot in the memory, a saved image, a text file of coordinates? You have posted the file array.txt and show an image, but which of them is the data you want to process? You mention "the white pixels in an array", but arrays do not have pixels, and in the image, the drawn line has a certain width of about 8 pixels and it is not clear, which of these many pixels you consider as "start" and how you want to treat this area (which is not a 2D line).

Please read How to ask a good question

[JRose]

@Jan: The input image is provided which is binarized and skelotonized. after that i saved the points in an array. This array is provided in the text file. You said tht it is already sorted. My question is: if i trace through the line from one end to the other, i will get certain cordinates. whether i can save these coordinates in an array as i trace through the line. when i go through the points in the array, its not ordered from one end of the skeletonized image to the other end.

Answer 1

[KSSV]

I = imread('curves.png');
I1 = rgb2gray(I);
[y,x] = find(I1) ; 

imshow(I)
hold on
plot(x,y,'r')

You see the lines are in order...that's why I am able to join them by a line, which lie exactly on the white region.

[JRose]

if we plot the lines it matches excatly. what i need is to get the points in an ordered manner. if the coordinate of white pixel on th eleft most end is 1st element of the array, the i need the send element as the nearest white pixel and so on. i have pllotted the points after saving it to array from the image and got excatly what you sai. but i couldn't get it as i mentioned above. my purpose is to take a line profile along these edges of the coordinate. thats why i need it in an ordered manner. please correct me if i'm wrong

[KSSV]

The points are in zig-zag way..you want a smooth curve instead?

[JRose]

no sir. I just need the points as it is in the figure. i have collected the points after skeletonizing. so it will be pixel by pixel. i just need to get the coordinates in an orderly fashion.

[KSSV]

They are already in orderly fashion.

comet(x,y)

[JRose]

Thank you for you answers.

Answer 2

[Sulaymon Eshkabilov]

Hi,

What you are trying to find out where the white pixels are residing, right?!

% This locates all white pixels accurately
AA = imread('curves.png');
A1 = AA(:,:,1);
A2 = AA(:,:,2);
A3 = AA(:,:,3);
Index1 = find(A1>0);
Index2 = find(A2>0);
Index3 = find(A3>0);
B1 = A1(Index1);
B2 = A2(Index2);
B3 = A3(Index3);
DATA = [B1, B2, B3];
imshow(DATA), shg
%% Given coordinates: don't seem to correct at all
array = load('array.txt');
AA = imread('curves.png');
A1 = AA(:,:,1);
A2 = AA(:,:,2);
A3 = AA(:,:,3);
B1 = A1(array(:,:));
B2 = A2(array(:,:));
B3 = A3(array(:,:));
DATA = [B1, B2, B3];
imshow(DATA), shg

Good luck.