How to do Raspberry Pi Zero Surveillance with Ruby

I've had my Raspberry Pi Zero for over a month, all powered and connected with its camera ready to go, but I had a problem positioning the camera because the ribbon cable I had was too short. So I finally got the extended ribbon cable and mounted it properly today. Prior to this, I was able to capture stills and also do broadcasts on YouTube (private feed). This was helpful to get it focused and pointing where I wanted it.

But what I really wanted was a way to capture an image and compare it to the previous image so that it could send it off to Dropbox only when there was a significant change. Here are the scripts I'm using:

Gemfile

source 'https://rubygems.org'

gem 'phashion'

camera.sh

#!/bin/bash

DATE=$(date +"%Y-%m-%d_%H%M%S")

raspistill --rotation 90 -q 10 -w 640 -h 480 -o $HOME/stills/$DATE.jpg
echo $DATE

find_non_dupe.rb

require 'rubygems'
require 'bundler/setup'

Bundler.require

now = Time.now
one_minute_ago = now - 60
pattern1 = one_minute_ago.strftime('%Y-%m-%d_%H%M')
pattern2 = now.strftime('%Y-%m-%d_%H%M')
files = Dir.glob("~/stills/#{pattern1}*.jpg")
files += Dir.glob("~/stills/#{pattern2}*.jpg")
last_img = nil
unique_dir = '~/unique'

files.each do |f|
  if File.exist?(File.join(unique_dir, File.basename(f)))
    puts "Skipping: #{f}"
    next
  end

  this_img = Phashion::Image.new f

  if !!last_img &&
    if this_img.duplicate? last_img
      puts "Duplicate: #{f}"
    else
      puts "Non duplicate: #{f}"
      FileUtils.cp f, unique_dir
    end
  end

  last_img = this_img
end

Then I use Dropbox-Uploader to send only the changes. Here's what it can capture and upload to Dropbox:

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Update: Here's how I mounted it.