Lots of existing image watermarking algorithm cannot resist brightness-and-contrast adjustment.In order to solve the problem,a blind robust quantization-based watermarking algorithm against brightness-and-contrast adjustment is proposed.An original image is transformed with discreet wavelet transform,and its low frequency band is split into non-overlapping blocks.Then,each block is conducted with discreet cosine transform.Finally,a watermark is inserted into low frequency coefficient from each block after discreet cosine transform through odd-even quantization.At the detection end,revision for resistance against brightness-and-contrast adjustment is imposed on the attacked watermarked image at first,and then a watermark is blindly extracted through odd-even judgment.Experimental results show that it has strong robustness towards brightness-and-contrast adjustment,and adding gaussian noise,adding salt&pepper noise,cropping,median filter,gaussian low-pass filter and JPEG compression.