# Create black columns/rows in image.

2 views (last 30 days)
Raldi on 26 Feb 2015
Commented: Raldi on 26 Feb 2015
Hi everyone,
I have an image and I want to only keep visible small patches of lets say 8x8 alternatively.
So I start at the beginning keep the first 8x8 patch, move right, make black the next patch, and so on until the end.
After that I move to the next row and I make the first patch black since we kept the one above it.
Moving like this I create a sort of a check board where the white parts have my original image.
What I did till now is
for ii = 1:it
Image = Image(1:step:end, 1:step:end);
end
After that I create a matrix of zeros at the dimensions of my original image and paint my under-sampled image
imageNew(1:step:end, 1:step:end) = Image;
This does not create the check-board effect though and I don't even know if it is good enough regarding the time it needs to run.
Has anyone any idea of how to go on about doing this?

Guillaume on 26 Feb 2015
I would do it like this:
pattern = zeros(11, 10); %number of rows must be odd
pattern(1:2:end) = 1;
mycheckerboard = imresize(pattern, 30, 'nearest');
imshow(mycheckerboard)
##### 3 CommentsShow 1 older commentHide 1 older comment
Guillaume on 26 Feb 2015
Oh, sorry misunderstood. Just to this then:
mycheckerboard = imresize(pattern, size(myimage), 'nearest');
myimage = immultiply(myimage logical(mycheckerboard));
Raldi on 26 Feb 2015
I am accepting this answer since it will help whoever read this to acieve what he want faster.

### More Answers (1)

Image Analyst on 26 Feb 2015
Why not simply use the checkerboard() function?????
##### 3 CommentsShow 1 older commentHide 1 older comment
Image Analyst on 26 Feb 2015
Then I'd just create one line then use repmat twice. I would not use Image as the name of a variable since image() is the name of a built-in function.
Raldi on 26 Feb 2015
I will try both suggestions and see how they work. Thanks for your time.

### Categories

Find more on Geometric Transformation and Image Registration in Help Center and File Exchange

### Community Treasure Hunt

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

Start Hunting!