Here is the code on the server side to convert images into base64 such that you can save them into browser JS database for offline retrieval.

#!/usr/bin/perl
use MIME::Base64 qw(encode_base64);

open (FILE, "z.png");
binmode(FILE);
$photobin = "";
while (read(FILE, $buf, 60*57)) {
  $output = encode_base64($buf);
  $output=~s/\n//g;
  $photobin = $photobin.$output;
}
print $photobin;
close(FILE);