Removing grey pixels from an image

Hi I have an image in which there are black pixels and gray ones. I am trying a way to remove the gray pixels and just keep the black ones. I dont want to do im2bw because I believe it will just turn the gray to black. Thanks for the help

[Walter Roberson]

What should the gray pixels be replaced with?

[Tarik Razak]

with white or nothing thanks

Answer 1

[Image Analyst]

You can't replace with nothing because the image must remain rectangular. So try this

imageArray(imageArray ~= 0) = 255;

That will turn all pixels not equal to zero (pure black) to 255 (pure white). If you need 1 instead of 255 (like it's a logical or floating point image) then just use 1 instead of 255.

imageArray(imageArray ~= 0) = 1;

Answer 2

[Shiva Arun Kumar]

Why would this not work?

bw=im2bw(I,0)

Where I is the image that was read in.