Separating particular pixels based on RGB value

I want to separate a group of pixels in an image which have RGB greater than [120 115 118 ] . How can I do it? The pixels having RGB values above the mentioned ones must appear in black color.How to do it? Thanks in advance.

Answer 1

[Walter Roberson]

locations = YourImage(:,:,1) > 120 & YourImage(:,:,2) > 115 & YourImage(:,:,3) > 118;
YourImage(repmat(locations,1,1,3)) = 0;

[Niranjan]

I am getting this error when I use it

??? Error using ==> repmat

Too many input arguments.

Error in ==> xxx at 8

I(repmat(locations,1,1,3)) = 0;

Should I fix the code as

I(repmat(locations,[1,1,3]) = 0; ???

[Walter Roberson]

Yes, that should work if you are using an old version of Matlab. Matlab has accepted the extended version for several years now.

[Niranjan]

oh thanks :)