Emergency need for help about Histeq

Hi friends,
  I want to apply HISTEQ function to an image, but I want that eliminate
background(gray-level of 0) befor doing that, how can I do that?
  plz help me,
  regards
	

Hi,

One way to eliminate the background pixels that have a
gray level of 0 would be to convert the 0's into some
other number- for example 255. you can use the find()
function to find all those coordinates that have 0
gray level. once you know the coordinates, set them to
white or mid-gray or anything else. then you can apply
the histeq function on your new image. you can also
loop through the entire image and change the 0's to
something else. You should understand however that the
contents of your image will be changed (as will your
histogram of course).
Use this code:
%----
[r c]=find(img==0)
% r will contain the row coordinate & c will contain 
% the column
%------
Or you can use this:
%-------------------------
[m n]=size(img);  % to get image dimensions
new_img=img; % Assign the image to a new variable

for i=1:m
  for j=1:n
   
    if(img(i,j)==0)
      new_img(i,j)%5;
    end
   end
end

histeq_img=histeq(new_img);
figure,imshow(histeq_img);
%-------------------------

Hope it helps.

E.S
	--- reza da <moshtaghtarin@mosh...> wrote:

> Hi friends,
>   I want to apply HISTEQ function to an image, but I
> want that eliminate background(gray-level of 0)
> befor doing that, how can I do that?
>   plz help me,
>   regards
> 
> 	
> 
> 
>