how to delete first row of pixel values?

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ravneet
ravneet on 31 Oct 2014
Commented: Rik on 12 Oct 2020
How can i delete or subtract the first row of pixels of an image from the complete image.

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Answers (2)

Geoff Hayes
Geoff Hayes on 31 Oct 2014
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.
Image Analyst
Image Analyst on 31 Oct 2014
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.
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marie lasz
marie lasz on 12 Oct 2020
Will it randomly delete the row or column? If I want to delete the selected row/column, then how can I continue?
Rik
Rik on 12 Oct 2020
It will not delete anything randomly, unless you assign a random value to row or column.

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