SignMyImage provides insertion of an invisible watermark (text) to the photo your sign. The sign is not visible at first sight, but the application can find it and read it. Signed photo is slightly changed on several places comparing to original photo. SignMyImage is able to detect and read your sign if you use strong JPEG compression (i.e. 50%), even if you scale or crop the photo slightly. An e-mail address is considered as a good for photo signing. The text for photo signing can be up to 27 letters long.