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# Detect motion or change between successive camera images.
# Snap a higher resolution photo when something has changed.
# Uses code originally from brainflakes in this thread:
# Copyright (C) 2014 Akkana Peck <>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
import os, sys
import time
import datetime
import re
import subprocess
sys.path.insert(1, os.path.join(sys.path[0], '..'))
import pycamera
from PIL import Image
class MotionDetector:
def __init__(self,
test_res=[320, 240], pir=None, rangefinder=False,
threshold=30, sensitivity=0,
test_borders=None, full_res=None,
localdir=None, remotedir=None,
crop=False, verbose=0):
'''test_res: resolution of test images to be compared.
XXX Can't we get that from the images passed in?
threshold: How different does a pixel need to be?
sensitivity: How many pixels must change?
verbose: print debugging messages.
test_borders: [ [ [left, right], [top, bottom] ], ... ]
testBorders are NOT zero-based, the first pixel is 1
and the last pixel is testWidth or testHeight
You can define areas to scan for changed pixels.
For example, if your picture looks like this:
"." is a street or a house,
"X" are trees which move like crazy when the wind is blowing,
to prevent constant photos, your setting might look like this:
testBorders = [ [[1,50],[1,75]], [[51,100],[26,75]] ]
area y=1 to 25 not scanned in x=51 to 100
Even more complex example
testBorders = [ [[1,39],[1,75]], [[40,67],[43,75]],
[[68,85],[48,75]], [[86,100],[41,75]] ]
crop: you may pass in a WxH+X+Y specifier, False (don't crop
at all), or '-' (crop to match the test borders)
self.verbose = verbose
self.localdir = localdir
self.remotedir = remotedir
# Do we have any sensors specified?
self.pir = None
self.rangefinder = False
if rangefinder or pir:
sys.path.insert(1, os.path.join(sys.path[0], '../rpi'))
if rangefinder:
import HC_SR04
self.rangefinder = HC_SR04.HC_SR04()
if pir:
import PIR_motion
self.pir = PIR_motion.PIR(pir)
# If sensitivity is nonzero, then we're using image detection.
# Otherwise we don't need things like threshold, test_res, etc.
if sensitivity:
self.test_res = test_res
if threshold:
self.threshold = threshold
self.threshold = 20
self.sensitivity = sensitivity
# Should we save debug images, so the user can tell where
# the test region is and what's happening?
# For now, tie it to verbose.
self.save_debug_image = self.verbose
# What area of the image should we scan for changes?
# Default setting (if None passed in): use whole image.
if not test_borders:
self.test_borders = [ [[1,test_res[0]],[1,test_res[1]]] ]
self.test_borders = test_borders
self.sensitivity = 0
self.save_debug_image = False
if full_res:
if len(full_res) == 2:
self.full_res = full_res
self.full_res = map(int, full_res.split('x'))
self.full_res = None
self.bufold = None
# What cameras are available? We may use a different camera
# for the regular low-res test images vs. the high-res snaps.
cams = pycamera.find_cameras(self.verbose)
if not cams or len(cams) < 1:
print "No cameras available"
if args.verbose:
print "Cameras available:"
for cam in cams:
print ' ', str(cam.__class__)
self.hicam = cams[0]
self.locam = cams[-1]
if args.verbose:
print "High-res camera:", str(self.hicam.__class__)
if self.sensitivity:
print " Low-res camera:", str(self.locam.__class__)
# Find a crop rectangle that includes all the test borders.
# XXX Should move crop functionality to
# and then it can let fswebcam do the work.
if crop == '-':
left = test_res[0]
right = 0
top = test_res[1]
bottom = 0
for piece in self.test_borders:
left = min(left, piece[0][0])
right = max(right, piece[0][1])
top = min(top, piece[1][0])
bottom = max(bottom, piece[1][1])
# Sanity check:
if left > 0 and right > left and right < test_res[0] and \
top > 0 and bottom > top and bottom < test_res[1]:
# But wait! We aren't done. The crop rectangle has to be
# scaled up to the full resolution of the image,
# we have no way of knowing what our final res is --
# even if we specify one, the camera may decide otherwise.
# The only way, apparently, is to take a full-res photo
# and see how big it comes out. And hope that doesn't change.
tmpfile = '/tmp/still.jpg'
res=full_res, format='jpg')
im =
self.full_res = im.size
print "Using full resolution of %d x %d" % self.full_res
img_data = None
im = None
convX = self.full_res[0] / self.test_res[0]
convY = self.full_res[1] / self.test_res[1]
self.crop = '%dx%d+%d+%d' % ((right-left)*convX,
left*convX, top*convY)
if self.verbose:
print "Cropping to test borders", self.crop
print "Not cropping: problem finding borders of test area:", \
left, right, top, bottom
self.crop = False
self.crop = crop # Should be either False, or a specifier
if self.verbose:
if self.crop:
print "Cropping to", self.crop
print "Not cropping"
# Use a temp file, or keep data in memory?
# The gphoto class has no way yet to save to memory,
# so we have to use a temp file if we're using gphoto.
if str(self.hicam.__class__).endswith('Gphoto'):
self.use_tmp_file = True
self.use_tmp_file = False
def cleanup(self):
if self.pir or self.rangefinder:
import RPi.GPIO as GPIO
if self.verbose:
print "Cleaning up GPIO"
def loop(self, secs=1):
'''Main loop detecting motion. The timeout you pass in here
doesn't really matter; the RPi is so slow at taking photos
and writing to ssh filesystems that you should expect
at least 10 seconds per loop in overhead, on top of any
delay you pass in.
while True:
# flush stdout, since we may be logging to a file.
def step(self):
'''Check camera snapshot or motion sensors to decide
whether there's anything worth taking a picture of.
if self.verbose:
print "" # Blank line so we can tell when each step starts
if self.sensitivity:
if self.use_tmp_file:
tmpfile = "/tmp/still.jpg"
self.locam.take_still(outfile=tmpfile, res=test_res)
im =
img_data = None
else: # keep it all in memory, no temp files
img_data = self.locam.take_still(outfile='-', res=test_res)
im =
different = self.compare_images(im)
print "Different?", different
if img_data:
# If the image didn't change, no point checking the other sensors.
if not different:
if self.rangefinder:
print "It's different. Checking the rangefinder ..."
dist = self.rangefinder.average_distance_in(samples=5)
if self.verbose:
print "Distance:", dist
# Use a range limit of 100 inches -- the rangefinder
# can't reliably see distances much greater than that anyway.
# Of course this should be configurable.
if dist >= 100:
if self.pir:
print "It's different. Checking the PIR ..."
if not self.pir.poll():
# If we get here, everything says there's motion.
# So take a full-res snapshot.
def get_outdir(self):
'''Does the remotedir exist and is it still accessible?
We check this every time, since a remote filesystem
could disappear at any moment, in which case we'll want
to revert to a local directory.
if self.remotedir and os.access(self.remotedir, os.W_OK):
return self.remotedir
return self.localdir
def get_snap_path(self, fileroot):
'''If there's been motion, snap a high-res photo.'''
# Use the remote directory if possible.
# But check for that every time, since the network might go down.
snapdir = self.get_outdir()
if not snapdir:
print "Not snapping full resolution, couldn't get output dir"
return None
now =
snapfile = '%s-%02d-%02d-%02d-%02d-%02d-%02d.jpg' % \
now.year, now.month,,
now.hour, now.minute, now.second)
return os.path.join(snapdir, snapfile)
def snap_full_res(self):
# XXX May want to save the first image with a fileroot of "first".
snappath = self.get_snap_path("snap")
if not snappath:
if self.crop:
# Snap data to memory, then pass it to jpegtran to crop.
# jpegtran can only write to stdout so we'll have to
# write it to the file ourselves.
if self.verbose:
print "Cropping"
if self.use_tmp_file:
tmpfile = "/tmp/still.jpg"
img_data = self.hicam.take_still(outfile=tmpfile,
p = subprocess.Popen(["/usr/bin/jpegtran",
"-crop", self.crop,
img_data = p.communicate()[0]
img_data = self.hicam.take_still(outfile='-',
# img_data is a StringIO instance.
# But Popen can't take a StringIO as input;
# instead, have to write the data into a pipe.
p = subprocess.Popen(['/usr/bin/jpegtran',
'-crop', self.crop],
# Better to use communicate() than write()
img_data = p.communicate(input=img_data.getvalue())[0]
# Or use instead of getvalue --
# not clear if there's any efficiency difference since
# we have to keep the whole string in mem either way.
snapout = open(snappath, 'w')
p = None
print "Saved high-res cropped still", snappath
self.hicam.take_still(outfile=snappath, res=self.full_res)
print "Saving high-res to", snappath
return snappath
def compare_images(self, new_image):
'''Compare an image with the previous one,
and return True if we think they differ enough.
new_image is a PIL.Image.
We'll remember the pixel data from the previous image.
bufnew = new_image.load()
if self.save_debug_image:
debugimage = new_image.copy()
debug_buf = debugimage.load()
debugimage = None
debug_buf = None
# XXX Modify threshold for time of day. Obviously this isn't
# the right way to do it, and it should be done by light levels.
now =
if (now.hour > 20 and now.minute > 45) or \
(now.hour <= 5 and now.minute < 30):
threshold = self.threshold / 3
threshold = self.threshold
# If bufold isn't set yet, it's our first time through.
# All we can do is copy it to prepare for the next time.
if not self.bufold:
self.bufold = bufnew
return False
changed_pixels = 0
for piece in self.test_borders:
for x in xrange(piece[0][0]-1, piece[0][1]):
for y in xrange(piece[1][0]-1, piece[1][1]):
# Just check green channel as it's the highest quality
pixdiff = abs(bufnew[x,y][1] - self.bufold[x,y][1])
if pixdiff > threshold:
changed_pixels += 1
# If debugging, rewrite changed pixels -> green
if (debug_buf):
debug_buf[x,y] = (0, 255, 0)
changed = changed_pixels > self.sensitivity
if debug_buf:
# Draw blue borders around the test areas no matter what,
# and add white borders if something has changed.
for piece in self.test_borders:
for x in xrange(piece[0][0]-1, piece[0][1]):
debug_buf[x, piece[1][0]-1] = (0, 0, 255)
debug_buf[x, piece[1][1]-1] = (0, 0, 255)
if changed:
if piece[1][0] > 1:
debug_buf[x, piece[1][0]-2] = (255, 255, 255)
debug_buf[x, piece[1][1]] = (255, 255, 255)
for y in xrange(piece[1][0]-1, piece[1][1]):
debug_buf[piece[0][0]-1, y] = (0, 0, 255)
debug_buf[piece[0][1]-1, y] = (0, 0, 255)
if changed:
debug_buf[piece[0][1], y] = (255, 255, 255)
if piece[0][0] > 1:
debug_buf[piece[0][0]-2, y] = (255, 255, 255)
self.bufold = bufnew
if changed:
print "=====================", changed_pixels, "pixels changed"
if self.save_debug_image:
print "Saving debug image to", self.get_snap_path("debug")"debug"))
elif self.verbose:
print changed_pixels, "pixels changed, not enough\t",
print str(
return changed
# Sample usage:
# -v -s 250 -t 30 -r 320x240 -b 100x100+130+85 -c - /tmp ~pi/trade/snapshots/
# -s 100 -t 30 -r 320x240 -b 70x65+125+100 -c - -v /root/snapshots /root/trade/snapshots >& /tmp/motion.out
# or, un-cropped:
# -v -r 320x240 -c 150x150+100+50 -b 50x50+125+75 /tmp /mnt/server/pix
if __name__ == '__main__':
import argparse
parser = argparse.ArgumentParser(description="""Monitor a camera and snap photos when something has changed.
Copyright 2014 by Akkana Peck; share and enjoy under the GPL v2 or later.""",
parser.add_argument("-s", "--sensitivity", type=int,
help="""Sensitivity: How many pixels must change?
If 0, we will use a motion sensor rather than image detection.""")
parser.add_argument("-t", "--threshold", type=int,
help="Threshold: How different does a pixel need to be?")
parser.add_argument("-r", "--resolution", default='320x240',
help="Resolution of the test image (WxH). Default 320x240.")
parser.add_argument("-f", "--fullres",
help="""Full resolution to save images.
Defaults to the resolution of the camera if we can get it.
Actual resolution may be different if the camera can't take a photo
at the specified resolution.""")
parser.add_argument("-b", "--borders",
help="""Borders of the test region we'll monitor.
A colon-separated list of wxh+x+y identifiers.
E.g. 100x50:5:20:100x50:200:150""")
# --crop can either be omitted (don't crop at all), included without
# an additional argument (crop to the test border boundaries),
# or included with its own WxH+X+Y specifier.
# With a default=False and nargs='?', argparse gives us False if -c
# isn't specified, None if it's specified with no argument, otherwise
# the argument that follows it.
parser.add_argument("-c", "--crop", nargs='?', default=False,
help="""Crop full-resolution images.
You can specify a crop region as WxH+0+0 (with the coordinates relative
to the test image size, not the final image size).
Specifying -c - or omitting the region specifier will result in
a crop to the boundaries of the test region.""")
parser.add_argument("-p", "--pir", type=int,
help="""Use a PIR motion sensor instead of a test image.
Specify Raspberry Pi pin number, e.g. 7.""")
parser.add_argument("-R", "--rangefinder",
action='store_true', default=False,
help="""Use a HC_SR04 rangefinder.
Assumes pins 23 for trigger, 24 for echo.""")
parser.add_argument("-v", "--verbose", action='store_true', default=False,
help="Verbose: chatter about what the program is doing.")
# type=argparse.FileType('w')
parser.add_argument("remotedir", nargs='?')
args = parser.parse_args()
print args
print "Crop:", args.crop
def resparse(res_str, default_res=None):
if not res_str:
return default_res
parsed_res = map(int, res_str.split('x'))
except ValueError:
print res_str, ": Please specify resolution as WxH"
if len(parsed_res) != 2:
print "Please specify resolution as WxH"
return parsed_res
test_res = resparse(args.resolution, [320, 240])
if args.rangefinder:
print "Using a rangefinder on pins 23 and 24 instead of test image"
elif args.pir:
print "Using pir sensor on pin %d instead of test image" % args.pir
print "Using test resolution of", test_res
full_res = resparse(args.fullres, None)
if full_res:
print "Saving stills using full resolution of", full_res
print "Will try to use full resolution of camera for saved stills"
if args.borders:
test_borders = []
border_list = args.borders.split(':')
# Each item in border_list is a WxH+x+y
for b in border_list:
match ='(\d+)x(\d+)\+(\d+)\+(\d+)', b)
if not match:
print "Couldn't parse", b, ": please specify borders as WxH+X+Y"
match = map(int, match.groups())
if len(match) != 4:
print "Need four items, WxH+X+Y, in", b
# Now match is (w, h, x, y).
# We need to turn that into [[x0, x1], [y0, y1]].
# XXX There is an off-by-one error because the original brainflakes
# XXX code uses 1 as its array boundary. Fix this!
test_borders.append([[match[2], match[2]+match[0]],
[match[3], match[3]+match[1]]])
print "Using test borders:", test_borders
# test_borders = [ [ [60, 200], [125, 190] ] ]
test_borders = None
if args.verbose:
print "No test region, using full image"
# If a crop region is specified, make sure it at least parses.
print "args.crop is", args.crop
if args.crop == None:
args.crop = '-'
elif args.crop and args.crop != '-':
match ='(\d+)x(\d+)\+(\d+)\+(\d+)', args.crop)
if not match:
print "Crop %s must be in format WxH[+X+Y], or just -" % args.crop
# else it's False, meaning don't crop
if args.verbose:
print "Parameters:"
for param in ('sensitivity', 'threshold', 'resolution', 'fullres',
'borders', 'crop', 'verbose', 'localdir', 'remotedir'):
if vars(args)[param]:
print ' %s: %s' % (param, vars(args)[param])
print ' %s not specified' % param
md = MotionDetector(test_res=test_res,
pir=args.pir, rangefinder=args.rangefinder,
threshold=args.threshold, sensitivity=args.sensitivity,
crop=args.crop, verbose=args.verbose)
except KeyboardInterrupt:
print "Interrupt: exiting"