find out the percentage of pixels having value 1

3 views (last 30 days)
Hi all,
I have a binary image (with values 0 & 1) of the dimensions 497*597. I want to calculate the fraction (%) of pixels with value 1 in each array of 3*3 pixels out of the full image. can anybody help me in this regard?
Any help is highly appriciated.
Thanks in advance
Bhavini
  2 Comments
Jan
Jan on 17 Jun 2013
Do you mean overlapping blocks, such that the first one goes from 1 to 3, the 2nd one from 2 to 4? Or should the block be mutually distinct?
Bhavini
Bhavini on 17 Jun 2013
Dear Jan,
Yes the blocks must be overlapping, starting from 1 upto 595 horizontally and 1 to 495 vertically.

Sign in to comment.

Answers (3)

Andrei Bobrov
Andrei Bobrov on 17 Jun 2013
Edited: Andrei Bobrov on 17 Jun 2013
a = randi([0 1],497,597);
ones_frac = conv2(a,ones(3),'valid')/9*100;
or if you have Image Processing Toolbox
ones_frac = blockproc(a,[3 3],@(x)sum(x.data(:))/9*100);

Bhomik Luthra
Bhomik Luthra on 17 Jun 2013
Lets take a random matrix of size 497*597. I have found the number of 1's in each 3*3 matrix in first horizontal row, u can do it for 497/3 rows by putting a for loop.
a = randint(497,597);
for i = 1:597/3
p(i)= length(find (a(1:3,3*i-2:3*i)==1))
end
p(i) returns the number of 1's in each 3*3 matrix.
Bhomik Luthra

Jan
Jan on 17 Jun 2013
For a binary image the percentage of 1's is the mean value multiplied by 100.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!