At present, most image watermarking scheme can not resist geometrical attacks, which restricts the application of digital watermarking techniques. In this paper, an image watermarking scheme based on histogram is proposed, since the histogram is not sensitive to geometrical transformation. Different groups of the image histogram bars are chosen, and the message is embedded to sum of every group by using Quantization Index Modulation (QIM). In watermark embedding scheme, an exact modification from histogram to image is proposed, and it can guarantee the distortion of image as little as possible. In watermark detection process, the same groups of image histogram bars are selected, and the message is extracted from the sum of each group by using nearest distance rule. Experimental results show the scheme is robust to geometrical attacks as well as compression and filtering.