Add a colum and a row of blank (white) values in an Image

Hello

I was thinking what would be the easiest way to add an extra column and row with values (255) in my image. I was thinking that is possible by reading the image size and adding an extra value to the dimensions but is there a easier and faster way ?

Thank you in advance

Answer 1

[Dimitris M]

Hello

Thank you very much for the info ! I managed to do it in an easier way using matlab's function padarray() , where you can also specify the value you want to add !

[Image Analyst]

That's what I thought of first but then I thought you meant that the extra row be "added" so I didn't mention padarray because that puts an extra layer all around - it doesn't just increase the dimension size by 1.

Answer 2

[Geoff]

Your best options (as far as I know) are:

1. Resize the image twice (once for new row, once for new column)

im(end+1, :) = 255;   % new row at end
im(:, end+1) = 255;   % new column at end

2. Create a new image, and copy your subimage in.

im1 = 255 * ones(size(im)+1);
im1( 1:end-1, 1:end-1 ) = im;

% Or, if large image, avoid unnecessary multiplications
im1 = zeros(size(im)+1);
im1( 1:end-1, 1:end-1 ) = im;
im1( end, : ) = 255;
im1( :, end ) = 255;

If adding data at the end, I would probably opt for (1). At worst, MatLab will create a new one and copy the data. At best, it'll expand the memory block and efficiently shuffle your data correctly. Otherwise, if you need to add rows/columns anywhere but the end, I would opt for (2).

Answer 3

[Image Analyst]

Try this little demo:

yourImage = magic(6) % Just a demo image.
[rows columns numberOfColorChannels] = size(yourImage);
if numberOfColorChannels == 1
  % Monochrome (grayscale) image.
  yourImage(rows+1, :) = 255
  yourImage(:, columns+1) = 255
else
  % For a color image.  I think this should work but I didn't test it.
  for c = 1 : numberOfColorChannels 
    yourImage(rows+1, :, c) = 255
    yourImage(:, columns+1, c) = 255
  end
end