Create black columns/rows in image.

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?

Answer 1

[Guillaume]

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)

[Raldi]

Hi Guillaume, this creates an actual check board image. What I want is instead of having the white parts, having what my image was supposed to have at those parts..

[Guillaume]

Oh, sorry misunderstood. Just to this then:

mycheckerboard = imresize(pattern, size(myimage), 'nearest');
myimage = immultiply(myimage logical(mycheckerboard));

[Raldi]

I am accepting this answer since it will help whoever read this to acieve what he want faster.

Answer 2

[Image Analyst]

Why not simply use the checkerboard() function?????

[Raldi]

No idea such a thing existed. Yet if possible I was more interested to do it myself not with a function by matlab.

[Image Analyst]

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]

I will try both suggestions and see how they work. Thanks for your time.