how to delete the white pixel(255) from grey scale image

I have to delete only 225 value white pixel from gray scale image. But i don't know how to identified each pixel from image and check if it is 255 and assign it's value to zero. Please help me

Answer 1

[Azzi Abdelmalek]

im(im==255)=0

[saravanakumar D]

how to check the pixel value of each cell?

[Azzi Abdelmalek]

You can use a for loop, but depending on what you want you can avoid it

[n,m]=size(im)   % im is your image nxm array
for ii=1:n
 for jj=1:m
   x=i(ii,jj)  %  your pixel at coordinate (ii,jj)
   % do
 end
end

[saravanakumar D]

function W = Classify(ImageRead)
% Step 1: Read image Read in
RGB = imread('E:\Working\mapping\first\map.png');
figure,
imshow(RGB),
title('Original Image');

% Step 2: Convert image from rgb to gray 
GRAY = rgb2gray(RGB);
g=GRAY;
imtool(GRAY);
title('Gray Image');

[r c]=size(g);
for i=1:r
  for j=1:c
      if (impixel(g,j,i)>254)
          {
              g(i,j)=0;
           }
      end
  end
end
figure,
imshow(z);

I am getting error like below

Error: File: maping.m Line: 20 Column: 23 The expression to the left of the equals sign is not a valid target for an assignment.

[Azzi Abdelmalek]

What are the symbols { and } , you are not programming with c, it's Matlab!

[saravanakumar D]

thank you

[saravanakumar D]

But i got error

[saravanakumar D]

can you please tell the correct expression for assign the 0 value to the matrix of the image?

[Azzi Abdelmalek]

Under what condition?

[saravanakumar D]

i have gray scale image. and i saved it in A. i want to convert white pixel(255) into black(0). So the condition is If pixel val is equal to 255 it turns into zero.

[saravanakumar D]

This is my program. It has major error, which i don't know.If i run this program matlab stop working.

function W = Classify(ImageRead) % Step 1: Read image Read in RGB = imread('E:\Working\mapping\first\map.png'); figure, imshow(RGB), title('Original Image');

% Step 2: Convert image from rgb to gray GRAY = rgb2gray(RGB); g=GRAY; imtool(GRAY); title('Gray Image');

[r c]=size(g); hold on for i=1:r for j=1:c if (impixel(g,j,i)>254)

                GRAY(i,j)=0;

        end
    end
end
hold off
imtool(GRAY);

[Image Analyst]

Why do you have both g and GRAY? You don't need two. And we're back to Azzi's original answer

g(g==255)=0;
GRAY(GRAY==255)=0;

Why didn't you follow his advice instead of doing things with for loops and two copies of the same image?