[filename, pathname] = uigetfile({'*.bmp'},'Text as image');
img=imread(filename);
img=im2double(img);
[r,c,ch]=size(img);
%imshow(img);
invert_img=img;
if(ch==1)
for i=1:r
for j=1:c
if(invert_img(i,j)==0)
invert_img(i,j)=1;
else
invert_img(i,j)=0;
end
end
end
end