I have in mind an idea for a generally accessible site that needs to allow images to be uploaded. But I’m stymied on how to prevent image spam: porn, ads in image form, etc.
Assumptions:
- I’m assuming that the spammers are clever, even human.
- I’m skeptical of the efficacy of image analysis software.
- I do not have the resources to approve all uploads manually.
- I am willing to spend money on the solution — within reason.
- This site will be location-aware, if that helps.
How does Flickr do it or imgur? Or do they?
There is no surefire method of sanitizing user-uploaded images. Even image analysis software will miss a small percentage of images and have false positives.
Flickr has community guidelines that say that you must flag your content appropriately, ie. if you’re uploading adult images, you need to flag them as restricted. Otherwise, they will take action against your account.
Often you’ll see compromises in cases where it’s not feasible to moderate all user uploads:
You could even combine approaches, such as having image analysis software trigger a “requires moderator attention” flag. Unfortunately, there’s no surefire method.