Image watermark layer question

[WRStrong]

I have several of my own photos that I need to add a simple watermark to; however, I would like to add stegonography to the watermarked layer in order to put the image information, the page that the image was to be placed on, etc... hidden within the watermarked layer. Is there a way that I can use php to view the stegonography data from the watermarked layer of the completed photo? If so, how?

[johanafm]

Yes.

Assuming for example that you are encoding data by manipulating colour intensity, all you have to do to decode data is go over the image pixel by pixel, read colour information and decoding your message. Easily done with iMagick extension. Not sure if gd has support for this as well.

However, a rescaling of the image, new compression level etc, will (most likely) break your message.

[WRStrong]

I know what I need to do to see if this is possible.

1) Create a watermark image
2) Insert a stegged data into the watermark
3) Embed the watermark with stegged data into an image
4) Attempt to read the stegged data from the watermarked image.

I can create a watermark image, actually create a steg and insert it into an image and then layered embed a watermark on an image; however, I have no idea how to look for stegged data in a watermark that's layered in an image.

Can anyone give me some assistance with this? I'd be eternally grateful.