With the advent of various image processing tools, images can be easily counterfeited or corrupted. Digital image watermarking has emerged as an important tool for protection and authentication of digital multimedia content. This paper presents a robust DCT-based blind digital watermarking scheme for still color images. RGB color space has been used to decompose the color cover image into three channels which can be taken as a gray scaled image. Experimental result shows that it sustains good visual quality even after attacks. Proposed technique is better in terms of payload, imperceptibility than available counterparts.