Due to the rapid growth and expansion of the Internet, the digital multimedia such as image, audio and video
are available for everyone. Anyone can make unauthorized copying for any digital product. Accordingly, the
owner of these products cannot protect his ownership. Unfortunately, this situation will restrict any
improvement which can be done on the digital media production in the future. Some procedures have been
proposed to protect these products such as cryptography and watermarking techniques. Watermarking means
embedding a message such as text, the image is called watermark, yet, in a host such as a text, an image, an
audio, or a video, it is called a cover. Watermarking can provide and ensure security, data authentication and
copyright protection for the digital media. In this paper, a new watermarking method of still image is
proposed for the purpose of copyright protection. The procedure of embedding watermark is done in a
transform domain. The discrete cosine transform (DCT) is exploited in the proposed method, where the
watermark is embedded in the selected coefficients according to several criteria. With this procedure, the
deterioration on the image is minimized to achieve high invisibility. Unlike the traditional techniques, in this
paper, a new method is suggested for selecting the best blocks of DCT coefficients. After selecting the best
DCT coefficients blocks, the best coefficients in the selected blocks are selected as a host in which the
watermark bit is embedded. The coefficients selection is done depending on a weighting function method,
where this function exploits the values and locations of the selected coefficients for choosing them. The
experimental results proved that the proposed method has produced good imperceptibility and robustness for
different types of attacks.