Positioning vulnerable water print generating and recognizing method capable of distigushing image and watermark distortion

The invention discloses orientation flimsy watermark generating and certificating method which can distinguish image and juggled watermark. Original image's wavelet low frequency coefficient of 4 bits is scalar quantized and used as watermark. The watermark is disturbed using random number to encrypt to improve its security. The encrypted watermark is embedded into LSB bit of original image. Original image's general picture is displayed through original watermark image's low frequency compress image recovered from watermark when certificating. Combining juggled position of image information located by difference value images with difference between image information and juggled watermark, how attacker juggled the image can be directly judged. At the premise of guaranteeing image's authenticity, switch efficiency of digital image is improved, which is helpful for digital images' application and spread. Adopting the invention, the authentication result is direct, visual effect is good, key's space is bigger and watermark algorithm is safer.