Jan Zindler knows how easy it is for children to stumble across pornographic photos while they surf the Internet. Now she has to worry about pornographic videos, too.
A mother of three from Austin, Texas, Zindler got a jolt several years ago when clearing out the "sent" folder of an e-mail account she shared with her teenage daughter. One of the e-mails in the folder contained a pornographic image.
"She was looking for a music site and accidentally put in a Web address with a typo. She was so surprised to find pornography that she sent an e-mail to her friend, saying, 'Check this out,'" Zindler recalled. "After I found that e-mail, I thought it was time to install parental controls."
Today, Zindler's attempt to control her children's online behavior is complicated by the fact that pornography and other content inappropriate for kids make their way onto the Web in both still-photo and video formats that are generated not only by adult-content producers but by amateur videographers and everyday Net users. In other words, the challenges of controlling access to online content, especially user-generated content, have grown as quickly as video sites such as YouTube have increased in popularity, said Chahab Nastar, chief executive of LTU Technologies, an image-recognition software company based in France.
As a result, experts say, parents and guardians need to rely on several forms of parental control software, instead of just one.
Some parental control software is designed to block access to inappropriate material by eliminating access to all Web sites but those that parents deem safe. Other technologies rely on searching for certain keywords or analyze the text on Web pages. More pertinent to the emergence of user-generated video, some software uses imaging technology to target obscene photos and videos by scanning pixels on a single Web page, or will check a series of images, frame by frame, in videos.
"The combination of text-based software, that bans keywords and blacklists URLs, and image-filtering technology would be the most efficient," Nastar said, but also noted that user-generated videos pose a particular technical problem.
"User-generated videos are harder to filter because the quality of the video is generally low and the images themselves may be faded, or the colors are off," Nastar said. "We find it is much easier to filter out professionally produced videos, because the image is usually sharper and the lighting and colors are better."
One LTU software product, Video-Filter, uses two layers of technology. One layer blocks blacklisted Web addresses and is similar to the technology that is used to detect or limit access to copyright material.
The second layer targets pornography, scanning numerous frames in a video to find redundancies in the pixels contained in each frame. Nastar said that the redundancies in such data create an algorithm that can be used to detect pornographic content in other videos.
Requests for LTU's video-scanning software has surged tenfold over the past year, with the vast majority of requests--80 to 90 percent--coming from Web sites that allow users to post videos on their site, Nastar noted.
"Demand has largely come from user-generated sites, as opposed to the search engine (Web sites)," Nastar said. "The reason is simple. They don't know what users are uploading and how they are tagging their videos."
Misleading category tags
Users posting video are usually asked to assign a category for their video--"animals," "sports," or "music," for example. But even those that are assigned a category may still be problematic.
One site had a number of videos submitted by users that were put in the "sports" category, but after showing two or three minutes of sports footage one video showed a 30-second pornography clip that had been inserted into the file, Nastar said. As a result, people assigned to review the videos by the Web site were not always catching the problems unless they watched every video in its entirety, he said.
Despite the surge in postings of user-generated videos, said John Carosella, vice president of content control for California-based Blue Coat Systems, there's usually enough text surrounding the videos to allow his company's technology to do its analysis.
Blue Coat hosts a database that categorizes Web sites. If a Web site is not included in its database, Blue Coat will analyze the text of the entire site, as well as which sites it links to. With this information, Blue Coat's technology draws conclusions about whether the Web site contains pornographic content.
Search engines often take different approaches to screening offensive content. Google, for example, will search for potentially inappropriate images and videos and include the source of a related Web site address as part of its response. That gives filter companies such as Blue Coat, which offer a product called K9 Web Protection Internet filtering software, the ability to categorize an image and block it from Google Video's image search.
"Google has made it easier for filter vendors to do their job," said Carosella.
Last year, however, the New York State Consumer Protection Board warned parents that children could easily access sexual-themed videos on Google Video. Google, as a result, said it would add a Safe Search feature to its site and restrict its "Top 100" category to family-friendly videos.
Carosella noted that Yahoo Video allows users to post videos without including the addresses of the Web sites that were the sources of the content, which in turn makes it virtually impossible for search-filtering software to screen out in appropriate images.
"Don't let your daughter do a report on beavers for her third-grade report. You're doomed," said Carosella, referring to the fact that the word beaver is used to describe not only the animal but, in vulgar usage, a woman's genitals.
Yahoo SafeSearch is designed to filter out adult-oriented text, video and images. However, even though SafeSearch was activated when conducting a video search using the word beaver, Yahoo returned several pornographic results. Yahoo noted it cannot guarantee that all sexually explicit content will be filtered out and that its terms of service prohibit the uploading of pornographic videos to its site.
Web sites that post videos submitted by their users, such as YouTube and MySpace, rely on screening technology and on the users themselves, who often notify the sites of content they believe is inappropriate, to weed out pornographic material. Other sites, such as AOL, rely on proprietary parental control filters and users to alert them to such content, and have full-time employees assigned to review videos whose posters tag them with the words naked or nude.
"We depend on our community of members to monitor the quality of the videos that are posted," said Andrew Weinstein, an AOL spokesman. "No one has yet to deliver a filter that determines if it is a pornographic picture, or a picture of a guy lifting weights without a shirt. The best filter is a community that is keeping track of these."
Zindler, meanwhile, said she is relying on parental control software provided by her Internet service provider.
"I started to use (Blue Coat's) K9 after my daughter came across that pornographic picture, but have since gotten DSL and am using their parental control software," Zindler said. "I don't think it's likely it'll happen again."