This paper proposes an improving method for the pixel-wise based image watermarking by using image averaging technique and prediction of tuned watermarked pixels. To reduce the error in the original pixel prediction process caused by the high different values of neighbor pixels in the watermarked image, the technique of image averaging is applied to host image in the embedding process, and the watermarked image in the extraction process. Furthermore, a tuning technique is implemented to reduce the prediction error in the original pixel prediction process. The experimental results show the improved performance in term NC at equivalent quality of watermarked images, compared to the previous methods. The robustness against various types of attack of the proposed method is also evaluate and compared.