2

どうやらこれは Python ではかなり一般的な問題です (こちら、こちら、こちらを参照) が、こちらから取ったこのスクリプトでなぜこれが起こっているのか頭を悩ませることはできません。問題の原因となっているスニペットと、Minimal Working Example (MWE) およびエラー トレースを添付しました。誰かが私が間違っていることを教えてもらえますか。ありがとうございました。

スニペット:

def captureTestImage():
    command = "raspistill -w %s -h %s -t 0 -e bmp -o -" % (100, 75)
    imageData = StringIO.StringIO()
    imageData.write(subprocess.check_output(command, shell=True))
    imageData.seek(0)
    im = Image.open(imageData)
    buffer = im.load()
    imageData.close()
    return im, buffer

エラー トレース:

Traceback (most recent call last):
  File "./test2.py", line 61, in <module>
    image1, buffer1 = captureTestImage()
  File "./test2.py", line 31, in captureTestImage
    im = Image.open(imageData)
  File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 1980, in open
    raise IOError("cannot identify image file")
IOError: cannot identify image file

MWE:

#!/usr/bin/env python

import StringIO
import subprocess
import os
import time
from datetime import datetime
from PIL import Image

# Motion detection settings:
# Threshold (how much a pixel has to change by to be marked as "changed")
# Sensitivity (how many changed pixels before capturing an image)
# ForceCapture (whether to force an image to be captured every forceCaptureTime seconds)
threshold = 10
sensitivity = 20
forceCapture = True
forceCaptureTime = 60 * 60 # Once an hour

# File settings
saveWidth = 1280
saveHeight = 960
diskSpaceToReserve = 40 * 1024 * 1024 # Keep 40 mb free on disk

# Capture a small test image (for motion detection)
def captureTestImage():
    command = "raspistill -w %s -h %s -t 0 -e bmp -o -" % (100, 75)
    imageData = StringIO.StringIO()
    imageData.write(subprocess.check_output(command, shell=True))
    imageData.seek(0)
    im = Image.open(imageData)
    buffer = im.load()
    imageData.close()
    return im, buffer

# Save a full size image to disk
def saveImage(width, height, diskSpaceToReserve):
    keepDiskSpaceFree(diskSpaceToReserve)
    time = datetime.now()
    filename = "capture-%04d%02d%02d-%02d%02d%02d.jpg" % (time.year, time.month, time.day, time.hour, time.minute, time.second)
    subprocess.call("raspistill -w 1296 -h 972 -t 0 -e jpg -q 15 -o %s" % filename, shell=True)
    print "Captured %s" % filename

# Keep free space above given level
def keepDiskSpaceFree(bytesToReserve):
    if (getFreeSpace() < bytesToReserve):
        for filename in sorted(os.listdir(".")):
            if filename.startswith("capture") and filename.endswith(".jpg"):
                os.remove(filename)
                print "Deleted %s to avoid filling disk" % filename
                if (getFreeSpace() > bytesToReserve):
                    return

# Get available disk space
def getFreeSpace():
    st = os.statvfs(".")
    du = st.f_bavail * st.f_frsize
    return du

# Get first image
image1, buffer1 = captureTestImage()

# Reset last capture time
lastCapture = time.time()

while (True):

    # Get comparison image
    image2, buffer2 = captureTestImage()

    # Count changed pixels
    changedPixels = 0
    for x in xrange(0, 100):
        for y in xrange(0, 75):
            # Just check green channel as it's the highest quality channel
            pixdiff = abs(buffer1[x,y][1] - buffer2[x,y][1])
            if pixdiff > threshold:
                changedPixels += 1

    # Check force capture
    if forceCapture:
        if time.time() - lastCapture > forceCaptureTime:
            changedPixels = sensitivity + 1

    # Save an image if pixels changed
    if changedPixels > sensitivity:
        lastCapture = time.time()
        saveImage(saveWidth, saveHeight, diskSpaceToReserve)

    # Swap comparison buffers
    image1 = image2
    buffer1 = buffer2
4

1 に答える 1

2

本当にばかげていると思いますが、これはソフトウェアの問題ではなく、不安定な Raspi の問題でした。カメラの適切なドライバーが読み込まれていないことが判明したため、カメラは写真を撮っていませんでしたが、代わりにエラーを生成していました。必要なのは再起動だけでした。

于 2013-10-15T20:21:17.213 に答える