On Sep 17, 2010, at 7:36 PM, Ashley Sheridan wrote: > > >>> >>> Even the stenography has its flaws. Opening the image in an image editor, then doing a select all and pasting as a new image would remove any hidden meta info, and saving a couple of times as a jpeg would destroy any detailed information without distorting the photo (assuming it was a photo and not a diagram which would look awful as a jpeg) >>> >>> I'm not sure if you ever had this at your school, but back when I was a kid, once a year class photos would be taken, as well as photos by yourself, even if you didn't want them. To ensure people paid for the proper photo, a large watermark was sprawled across the photo. It took a little while, but with a decent image editor you could pull out that watermark from the scanned in photo and have a good quality photo without paying for it. I'm not saying we should all do this (the photographer needs to be paid somehow!) but I'm saying it's possible if you have the time, inclination and means. >>> >> >> Actually Ash, properly done stenography is actually embedded it the pixels - not the metadata and can be placed such that only when the image is reduced to x degraded percent is it lost which removes the value of the full res image. >> >> However, the power of real stenography for copyrights (and not for spying) is about the fact that the real user uses the image and if it gets copies by someone the stenography copyright signatures remain and the copier doesn't know about them >> >> Tom >> >> > > > I know this is getting a little off-topic here, but surely the way a > jpeg destroys data in an image would destroy the stenography information > too? To the human eye all would appear normal, but the copyright info > would be lost? > > I don't know much about this sort of thing, so I'm making assumptions > here. > Totally depends on the approach. Both jpeg and jpeg 2000 have their own mathematical characteristics which can be properly exploited. Nevertheless, I say again the key is to add something is that if an employee of a customer who purchases the image and resells it that you have a possibility to prove. Yes really smart bad people can defeat but 1) most of these aren't stealing your pictures and 2) the others don't know you have embedded a copyright. tom Tom -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
