PDF文档权限如打开打印修改操作限制破密文件！-PDF document file permissions broken secret!

This based on stegnography to hide a secret image in the ordinary image and to recover the orignal secret image-This is based on stegnography to hide a secret image in the ordinary image and to recover the orignal secret image

Stegnography the practice of concealing messages or information within other non-secret text or data.