There is so much wrong with this beyond that. I've fixed a bunch of things and leave it to you to fix the rest (like d and p being 1-D or 2-D cell arrays):
grayImage = imread('peppers.png');
% Get the dimensions of the image.
% numberOfColorBands should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
% It's not really gray scale like we expected - it's color.
% Use weighted sum of ALL channels to create a gray scale image.
grayImage = rgb2gray(grayImage);
% ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
% which in a typical snapshot will be the least noisy channel.
% grayImage = grayImage(:, :, 2); % Take green channel.
end
% Resize the image
smallImage = imresize(grayImage,[16 16]);
c = dec2bin(smallImage,8);
d = cellstr(dec2bin(smallImage,8))';
[rows, columns, numberOfColorChannels] = size(d)
p = d; % Copy the cell array into p
for i = 1 : rows
for j = 1 : columns
if strcmp(d{i, j}, '00000001') || strcmp(d{i, j}, '10000000')
p{i,j} = '00000001';
else
p{i,j} = '10000000';
end
end
end
msgbox('Done!');
