On Sep 17, 2010, at 7:25 PM, Ashley Sheridan wrote: > On Fri, 2010-09-17 at 19:20 -0400, TR Shaw wrote: >> >> On Sep 17, 2010, at 6:58 PM, Ashley Sheridan wrote: >> >>> On Fri, 2010-09-17 at 18:56 -0400, TR Shaw wrote: >>>> >>>> On Sep 17, 2010, at 6:49 PM, Ashley Sheridan wrote: >>>> >>>> > On Fri, 2010-09-17 at 18:41 -0400, TR Shaw wrote: >>>> > >>>> >> Gary >>>> >> >>>> >> you do realize that if you display the image in a browser without the watermark, simple drag and drop can copy the image as is (eg without the watermark) >>>> >> >>>> >> Tom >>>> >> >>>> >> On Sep 17, 2010, at 6:21 PM, Gary wrote: >>>> >> >>>> >>> >>>> >>> ""Gary"" <gpaul@xxxxxxxxxxxxxxxx> wrote in message >>>> >>> news:1F.27.30333.1D5E39C4@xxxxxxxxxxxxxxx >>>> >>>> Is there a way to insert a watermark on an image as it is being uploaded >>>> >>>> to the image file, then removed when it is called from a database to be >>>> >>>> viewed on a website? >>>> >>>> >>>> >>>> The rational behind this is I have a photographers site I am doing, and I >>>> >>>> am limiting the size of the images somewhat to reduce pilferage and I >>>> >>>> would like to be able to show the images a little larger, hence with a bit >>>> >>>> more clarity and detail. >>>> >>>> >>>> >>>> Thanks for your input. >>>> >>>> >>>> >>>> Gary >>>> >>> >>>> >>> More info. >>>> >>> >>>> >>> I was asked off board where the watermark would show, so I am sorry if I was >>>> >>> less than clear. The watermark would show on an image that is being >>>> >>> downloaded from the server. If this were to work, I could let viewers see >>>> >>> an image with a size of 640px in width to show clarity, (they are only able >>>> >>> to see an image now with a width of 250 px now) should they decide to help >>>> >>> themselves to it, it would download with a watermark on it, but the >>>> >>> watermark would not appear on the web page itself. >>>> >>> >>>> >>> Gary >>>> >>> >>>> >>> >>>> >>> >>>> >>> __________ Information from ESET Smart Security, version of virus signature database 5458 (20100917) __________ >>>> >>> >>>> >>> The message was checked by ESET Smart Security. >>>> >>> >>>> >>> http://www.eset.com >>>> >>> >>>> >>> >>>> >>> >>>> >>> >>>> >>> >>>> >>> -- >>>> >>> PHP General Mailing List (http://www.php.net/) >>>> >>> To unsubscribe, visit: http://www.php.net/unsub.php >>>> >>> >>>> >> >>>> >> >>>> > >>>> > >>>> > There's no way to do this. Anything you see in your browser has already >>>> > been downloaded in some form onto your computer, and once that happens >>>> > it's out of your control. PHP has no way to detect if the image is being >>>> > requested by the browser to view or download, so can't do what you want. >>>> > >>>> > Besides which, if an image is displayed in the browser, there are dozens >>>> > of ways to get at it, from right clicking and saving it, using the media >>>> > tab of the file info dialogue (firefox), using firebug to view it, >>>> > saving it from the cache, saving the whole page, using wget to spider >>>> > and save that page, etc. >>>> > >>>> > The only way to do what you want is to have your own custom browser app >>>> > (possibly written in Java) but even then someone could simply do a print >>>> > screen. >>>> > >>>> > At the end of the day, if you want to prevent people downloading your >>>> > images, then just don't show them the image. >>>> >>>> Actually you can. Serve up an image from the DB and add watermark or whatever on the fly for web browsers. If a user downloads (assuming that s/he bought the image or the image is a "freebie" ) the image comes from the DB directly to the user using download headers. >>>> >>>> Tom >>>> >>> >>> But the downloading will still be happening through the web browser, which PHP won't be able to recognise. >>> >> >> >> True but the key is that you only download IF the person has paid - lets face it once someone has paid and accessed the image all bets are off as for control. >> >> >> Now, for those paid for files he could implement steganography to hide his watermark/copyright in the image for later legal action if required. >> >> >> Tom >> >> > > 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
