文件列表:

download_imgs\rescale_max_size.m (1195, 2007-10-13)
download_imgs\trim_border.m (341, 2007-08-21)
download_imgs\temp (0, 2007-11-17)
download_imgs\cvlib_mex.mexglx (100282, 2007-04-29)
download_imgs\downloadphotos_gps.m (12801, 2008-04-29)
download_imgs\fast_resize.m (913, 2008-04-29)
download_imgs\libcv.so.1 (3980937, 2007-04-26)
download_imgs\libcxcore.so.1 (3238114, 2007-04-26)
download_imgs\my_rgb2gray.m (302, 2008-04-29)
download_imgs\notes.txt (197, 2007-09-25)
download_imgs\remove_frame.m (2514, 2007-10-13)
download_imgs (0, 2008-04-29)
query_imgs\get_imgs_dyn_timeskip.py (11928, 2008-04-29)
query_imgs\place_rec_queries.txt (6643, 2007-09-26)
query_imgs\flickrapi2.py (16781, 2008-08-18)
query_imgs (0, 2008-08-18)

This code was original written by Tamara Berg, then extended by James Hays (jhhays@cs.cmu.edu) updated - 8/18/2008 - In previous archives, I had included flickrapi.py instead of flickrapi2.py which handles missing XML fields. The code, as is, was used to generate the geotagged database for IM2GPS: estimating geographic information from a single image. James Hays and Alexei A. Efros. CVPR 2008. http://graphics.cs.cmu.edu/projects/im2gps/ The code operates in two distinct stages: first querying for images, then downloading them. -------------------- 1) Querying -------------------- The image query code is written in Python, using the Python Flickr API interface which gives acknowledgements and credits in the top of flickrapi2.py. To use the Flickr API, you need an API key (see http://www.flickr.com/services/api/) which you will need to enter in get_imgs_dyn_timeskip.py (line 31) in addition to changing the output path (line ***). The query script, get_imgs_dyn_timeskip.py, searches for Flickr images with keywords listed in place_rec_queries.txt. place_rec_queries.txt contains negative text constraints, as well, at the bottom of the file. You can change these to whatever keywords you want. For each keyword get_imgs_dyn_timeskip.py will produce a text file containing information about the images found. Keywords can be either tags or, as currently specified, any text associated with the image including title and description. Querying FAQ a) I don't care about geo-tagged images, I want them all. As is, get_imgs_dyn_timeskip.py will only retrieve geotagged images. To retrieve all images delete the bbox="-180, -90, 180, 90", accuracy="6" " constraints to the Flickr search API calls (lines 114 and 175). b) Why does get_imgs_dyn_timeskip.py look so complicated / run so slow? The Flickr API will disable your key if you query too rapidly, so it makes sense to do large queries which return hundreds of results. But doing big queries is problematic, because there seems to be a long existing and long known bug in the Flickr search function- for any given search, after the 1500th or so image, duplicates will start to appear. You can get around this by doing time-bounded queries, but then you run into the problem of having to do too many small queries. Therefore get_imgs_dyn_timeskip.py does queries within dynamically sized time intervals, always trying to have about 400 results for a query. If few images are being found because you've done a rare query, the time interval for queries will tend to expand. If too many images are being found the time interval will shrink. As the time window moves towards the present day it will tend to get narrower, because the rate that people upload pictures to Flickr seems to be increasing. c) Will I get duplicate images? No, actually. Lets say your keyword file is # first line of file mountain lake -city # end of file First the script will find all of the images that have the text "mountain" associated with them, but not "city". Then for the next keyword "mountain" will be used as a negative constraint. So the queries will actually be "mountain -city" then "lake -city -mountain", etc. Images that have both "mountain" and "lake" will be found with the first query and not the second. d) Can I run the script in parallel to speed things up? It's possible, but it's more likely to get your API key disabled and you'll have to take steps to ensure that you're not getting duplicate images, for instance by manually adding the keywords that one thread is using as negative constraints to the other threads. e) Couldn't I just check for duplicates after querying before downloading? Sure, although I haven't written code to do that. Flickr images have unique serial numbers so it's possible. -------------------- 2) Downloading -------------------- The image download code is written in Matlab. It accesses images on Flickr's http server instead of going through the API, and thus doesn't require an API key. It reads the text files produced by get_imgs_dyn_timeskip.py, downloads the photo, and saves all of the image attributes (tags, interestingness, long/lat, etc...) as a matlab cell string array in the comment field of each jpg. Use imfinfo() to read them later. The main function is downloadphotos_gps.m. You'll need to set the paths at the top. if you've changed any of the fields saved by they query script you'll need to edit the download script since it expects certain fields in certain order (see the source code for an example). Downloading FAQ a) What size images will this get? Currently the code will try and find the Flickr "Large" size photo, which has max width or height of 1024. Failing that it will try to get the "Original" size photo. If the "Original" is larger than 1024 height/width it will be downsampled to 1024. If it is smaller than 500 height or width it will be thrown away. Otherwise the image will be kept. A significant fraction of images are too small by this criteria and thus are thrown away. b) How are the images written to disk? Since most file systems have trouble with thousands of files in a directory, the images are put into a hierarchy of directories that contain no more than 1000 images each. The hierarchy is base_db_path / keyword / numbered subdir / img_name for example Flickr_geo_and_gps/Argentina/00015/315157387_c36ba74681_100_23812473@N00.jpg The image filenames contain the photo id, secret, server id, and owner which can be used to trace the .jpg back to its source on Flickr. See the source code for examples of how the URLs are constructed. c) What about all those annoying artsy borders that people put around their Flickr photos? The download script tries to remove them, see remove_frame.m d) Can I run the download script in parallel? Yes, I've run 15 copies in parallel in the past. I wouldn't recommend doing any more than this because Flickr could get mad at us. They're aware that researchers are using Flickr as a data source but their main concern is that we don't impact the quality of service for the millions of people who use Flickr. To run multiple scripts in parallel you'll need to split up the text files from the query process manually, then change the path in downloadphotos_gps.m for each call. e) What are these libraries and mex files? Matlab's image resizing is slow so I call the open_cv image resize through a wrapper. If that's not working you can just change the function calls to fast_resize to Matlab's slower imresize(). f) What about copyrights? It is worth noting that Flickr allows photographers to specify Creative Commons licenses for their images instead of the default "all rights reserved". This script saves the license info with each .jpg file, so you can pick out Creative Commons images after the fact (in my experience it's less than 10% of images) It is also possible to restrict the search to images with certain licenses at query time. See the Flickr API for details.

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