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Rewrite of the python image downloading code from which does not leave gaps in the numbering, allows arbitrary starting numbers and uses generators to make the code a bit more readable
from imutils import paths
import argparse
import requests
import cv2
import os
import numpy as np
# Adapted from
# fixes the following issues with the original:
# 1 - files are always saved as .jpg even if they are not in JPEG format
# This version uses open CV to write the image files so they are really always JPG
# 2 - failed files leave gaps in numbering
# 3 - numbering always starts from zero
# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-u", "--urls", required=True,
help="path to file containing image URLs")
ap.add_argument("-o", "--output", required=True,
help="path to output directory of images")
ap.add_argument("-s", "--start", required=False,
help="First number to start at",
ap.add_argument("-v", "--verbose", required=False,
help="Print information as we go",
action="store_true", default=False)
# grab the list of URLs from the input file, then initialize the
def read_url_list(filename):
return open(filename).read().strip().split("\n")
# generator to read URLs and return data
def read_urls(urls, is_verbose=False):
for url in urls:
# try to download the image
if is_verbose:
print("Downloading {}".format(url))
r = requests.get(url, timeout=60)
yield ((url, r.content))
except requests.exceptions.RequestException as e:
print("Error downloading {} : {}".format(url, e))
# test if files are image data that OpenCV can read
def return_images(file_contents, is_verbose=False):
for url, data in file_contents:
# convert to numpy array that OpenCV can read
nparr = np.fromstring(data, np.uint8)
# attempt to decode data as image
img_cv = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
if img_cv is None:
if is_verbose:
print("Skipping {} - not an image".format(url))
# return the image
yield ((url, img_cv))
except Exception as err:
if is_verbose:
print("Error parsing {} : {}".format(url, err))
def write_images(images, output_dir, start=0, is_verbose=False):
file_num = start
for url, image in images:
p = os.path.sep.join([output_dir, "{}.jpg".format(str(file_num).zfill(8))])
cv2.imwrite(p, image)
file_num += 1
if is_verbose:
print("{} <- {}".format(p, url))
if __name__ == "__main__":
args = vars(ap.parse_args())
output_dir = args["output"]
is_verbose = args["verbose"]
start = int(args["start"])
urls = read_url_list(args["urls"])
url_data = read_urls(urls, is_verbose)
images = return_images(url_data, is_verbose)
write_images(images, output_dir, start, is_verbose)

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@jpcadena jpcadena commented Jun 4, 2021

Good afternoon Dave! I have an issue while running your code from Pycharm console. I get the following error in red letters:

usage: [-h] -u URLS -o OUTPUT [-s START] [-v] error: the following arguments are required: -u/--urls, -o/--output

Any help with this issue? I don't understand too much about the argparse function. Hope you can reply to me. Thx!


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@davesnowdon davesnowdon commented Jun 5, 2021

Hi, the program needs 2 things to run: 1) a text file with a list of URLs (one per line) and the directory where the downloaded images should be written. So if your list of URLs was in a file called "urls.txt" and you wanted the images to in a directory called "downloads" the arguments to the program would be
-u urls.txt -o downloads

In PyCharm the above would go in the "parameters" box of the Run/Debug configuration. Or you could just run the program from the command line, like this:
python -u urls.txt -o downloads

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