How to draw a horizontal line passing through the given points?

I have a word in which I have the row index of the first black pixel in the column and the row index of the last black pixel in the column. So I want to draw a horizontal line joining all the first black pixels and all the last black pixels so that i can get the size of the word from those lines. Please help me with the code. First pixels

last pixels

Answer 1

[Image Analyst]

Let's say your image is called grayImage, and that your pixel columns are called "firstPixels" and "lastPixels" and of course you have your row indexes "firstRow" and "lastRow". So then just loop

for k= 1 : length(firstPixels)
    % Set row to zero for this word in the first row.
    grayImage(firstRow, firstPixels(k):lastPixels(k)) = 0;
    % Set row to zero for this word in the last row.
    grayImage(lastRow, firstPixels(k):lastPixels(k)) = 0;
end

[Meghashree G]

sir its displaying nothing.should we use plot or something to see the line ?

[Image Analyst]

You have to call imshow() after you change the grayImage variable.

If you don't want lines burned into the image, you can use the line() function to put it into the graphical overlay.

[Poornima Gokhale]

What does this grayImage function do?

Answer 2

[Image Analyst]

You might want to look at Brett's File Exchange submission: http://www.mathworks.com/matlabcentral/fileexchange/48466-text-recognizer