Creating a plot of intensity of pixels across an image using MATLAB?

Hi am a newbie to MATLAB. Can anyone suggest me a code to plot a graph for number of pixels in each column of an image? any serious help would be appreciated.Thanks in advance.I need a code to get the density of black pixels in every column of an image.

Answer 1

[Walter Roberson]

It is not clear to me what kind of output you want, but

bar(mean(~im))

should calculate the average density of black (== 0) down the columns and draw a bar chart of the result.

[Sumera Yamin]

hi, how can one plot the histogram for sum of intensities on the image along x and y axis.

[Walter Roberson]

Like

histogram(sum(YourImage,1))
%and
histogram(sum(YourImage,2))

Answer 2

[Doug Hull]

Since you want the density of black pixels in an image, I am assuming you have an image that is:

• Intensity based (not RGB, or indexed)
• You want only pure black pixels (value 0 for black, 255 for white)

(edit your question if these assumptions are wrong)

im = round(rand(5))*255

subplot(2,1,1)
image(im);
colormap(gray)

   isBlack = (im == 0);
  numBlack = sum(isBlack);
  numPix   = size(isBlack,1);
  denBlack = numBlack/numPix;
subplot(2,1,2)
plot(denBlack)