add vertical lines to an image

i've loaded an image and i'd like to add some vertical lines on it,could anybody help me? the image is voltage curve and i need the exact value of the voltage at any time. so i decided to add vertical lines to it,and then by using graph digitizer extract the values.

Answer 1

[Image Analyst]

Is it a color image or a grayscale image? Do you want the lines burned into the image, or above it in the overlay?

[rows, columns, numberOfColorChannels] = size(yourImage);
spacing = 50; % Whatever.
for row = 1 : spacing : rows
  line([1, columns], [row, row]);
end
for column = 1 : spacing  : columns
  line([column, column], [1, rows]);
end

If you want them in the overlay, simply use the line() function. If you want it burned into a grayscale image:

grayImage(:, columnNumber) = 255; % White = 255, can pick any intensity.
grayImage(rowNumber, :) = 255;

Same thing for color, just do it in whatever color channels you want. You can also control the color of the line that way.

[maryam]

thank you very much,ur answer is compeletly useful for my work. :)

[Journi Northorp]

Can you give me an example please? I have to make vertical lines in white for every other column of a 20x20 matrix.

[Image Analyst]

Try this:

m(:, 2:2:end) = 255;

where m is your matrix.

Answer 2

[David Sanchez]

The following draws a vertical line on your_image from pixel (20, 10) to pixel (20, 50):

image(your_image);
hold on
x=[20 20];
y=[10 50];
line(x,y)
hold off