An Algorithm for Image Authentication Based on Fragile Watermarking

The algorithm of discrete wavelet transform and Arnold transform combined is developed to achieve the integrity authentication of color image contents through embedding fragile watermarking. Firstly, a new watermarking image is generated with the XOR between the original binary watermarking and the image which is processed with Arnold transform. When the watermark is embedded, the original image color is converted first and the brightness component is decomposed into three discrete wavelets. Then, the low-frequency approximation sub-image of third-level is extracted, and its least significant bit is set 0. Finally, the new watermark is embedded into its least significant bit. Through comparing the pixels of original watermarking image with that of the extracted watermarking image, it can be determined whether the watermarking image has been tampered, and the tampered area of the original color image is located. The results of simulation experiment shows that the algorithm has the strong capabilities of detection and location and it also can keep the original image quality well.