how to delete first row of pixel values?

How can i delete or subtract the first row of pixels of an image from the complete image.

Answer 1

[Geoff Hayes]

Ravneet - if you want to delete just the first row of your image, then you could do something like the following

 myImage = imread('someImage.jpg');

 if ndims(myImage)==3

    % there are three dimensions
    myImage(1,:,:) = [];

 elseif ndims(myImage)==2

    % there are two dimensions
    myImage(1,:) = [];
 end

We access all elements in the first row as either myImage(1,:,:) or as myImage(1,:) and set that row to be empty.

Answer 2

[Image Analyst]

Geoff gave you the way to delete the first row of pixels. If you want to "subtract the first row of pixels of an image from the complete image." then you can do this (untested, and for a gray scale image).

% Get size of image
[rows, columns, numberOfColorChannels] = size(grayImage);
% Extract first row:
firstRow = grayImage(1,:);
% Replicate it to form an image of the same size:
replicatedImage = double(repmat(firstRow, [rows, 1]));
% Do the subtraction
differenceImage = double(grayImage) - replicatedImage;
imshow(differenceImage, []);  % Need to use [] or won't see anything.

[marie lasz]

hey, how you can delete any row or column pixels of a rgb image ?

[Image Analyst]

Try

rgbImage(row, :, :) = [];

or

rgbImage(:, column, :) = [];

If that doesn't work, write back.

[marie lasz]

Will it randomly delete the row or column? If I want to delete the selected row/column, then how can I continue?

[Rik]

It will not delete anything randomly, unless you assign a random value to row or column.