plotting an matrix on top of an image

I have an image and I devided it into 10 to 10 matriz and then allocate specific number to each elements. Now, I want to plot the matrix beside or the top of my image, So I can see the number for each elements. can you help me with that?

[Ameer Hamza]

Can you show some examples? How you divided the original image? How do you want to plot it again over the original image? You can attach an image of a similar output image.

[talayeh tavangar]

my image is a 600*800 matrix I take an average to make it 10*10 and then allocate specific number to each element

[talayeh tavangar]

now I want to show the matrix on the top of my original image

Answer 1

[S. Walter]

You can plot your image , set your hold to on (https://www.mathworks.com/help/matlab/ref/hold.html) and then plot your 10 x 10 matrix.

% Using the example on https://www.mathworks.com/help/matlab/ref/image.html
C = [0 2 4 6; 8 10 12 14; 16 18 20 22];
% Plot C with scaled mapping
image(C,'CDataMapping','scaled')
% Make a 10x10 matrix
[x,y] = meshgrid(linspace(0.5,4.5,10),linspace(0.5,3.5,10));
% Set the hold to on
hold on
% plot the 10x10 matrix
plot(x,y,'r.')

This should give you the following image:

[talayeh tavangar]

Thanks.

can you tell how I can set [x,y] to my predefined matrix. I used [x,y] = v(1:10,1:10); but I faced error

[S. Walter]

I am not sure I understand the question. In the quick example above, I used linspace (https://www.mathworks.com/help/matlab/ref/linspace.html) to create the matrix. In and of itself,

[x,y] = v(1:10,1:10);

doesn't make sense - it will throw an error because Matlab won't know how to assign the 10x10 matrix that you're pulling out to the variables x and y.

[talayeh tavangar]

I mean. I have already created the 10 in 10 matrix and now I want to plot it on my original image. So I donot want to use linespace for creating a matrix

[Image Analyst]

Do you mean you want to call text(x,y,string) to overlay a string on the point with the coordinates, like

str = sprintf('(%.2f, %.2f)', x, y);
text(x, y, str, 'Color', 'r', 'FontSize', 15);

[S. Walter]

if you already have a matrix, say it's "v", you can just do

plot(v,'r.')

to plot it as red dots.

The main way to make sure you can plot over an existing plot is to ensure

hold on

is included before your next plot command.

[talayeh tavangar]

thanks

this is my code but it only shows my original image and not any red node

grayImage = rgb2gray(f);

[rows, columns, numberOfColorchannels] = size(grayImage);

% Make grid every 10 rows

for row = 60 : 60 : rows;

grayImage(row, :, :) = 255;

end

% Make grid every 10 columns

for col = 80 : 80 : columns;

grayImage(:, col, :) = 255;

end

imshow(grayImage);

grayLevel = grayImage(9, 6);

hold on

% plot the 10x10 matrix

plot(v,'r.')

[S. Walter]

I am not sure where you're defining "v", since that's not included in your code.

Your code, as it stands, changes every 60th row and 80th column to white. I used

grayImage = imread('corn.tif',3);
%%%%%%%%%%%%%%%%%%% BEGIN YOUR CODE %%%%%%%%%%%%%%%%%%%
[rows, columns, numberOfColorchannels] = size(grayImage);
% Make grid every 10 rows
for row = 60 : 60 : rows;
	grayImage(row, :, :) = 255;
end
% Make grid every 10 columns
for col = 80 : 80 : columns;
	grayImage(:, col, :) = 255;
end
imshow(grayImage);
%%%%%%%%%%%%%%%%%%% END YOUR CODE %%%%%%%%%%%%%%%%%%%
% Make a set of points to plot - this is arbitrary
[x,y] = meshgrid(linspace(0,312,5),linspace(0,415,8));
% hold on to the figure and axes
hold on
% Add the red dots
plot(x,y,'ro','MarkerFaceColor','r')

and I get the following:

[talayeh tavangar]

V is a 10 in 10 matrix. When I put v instead of x and y the final picture does not show any thing

[S. Walter]

When you take the code I supplied above, does the same problem happen? Do you still show nothing?

Can you confirm that your "v" matrix isn't outside the image boundaries?