Digital images face copyright infringement issues during network transmission and sharing, especially when high-precision color images are copied, tampered with, or abused without authorization. To address this challenge, this paper proposes an image watermarking algorithm based on 3D scanning technology. This paper uses high-precision 3D scanning technology to obtain the three-dimensional point cloud data of color images, pre-processes the data, and projects the data onto a two-dimensional plane to generate an RGB color image. This paper uses an advanced algorithm based on three-dimensional discrete cosine transform (3D-DCT) and singular value decomposition (SVD). The two-dimensional color image is processed in blocks, and a three-dimensional discrete cosine transform is performed on each image block. Then, the transformed intermediate frequency coefficients are subjected to singular value decomposition, and the designed watermark information is embedded into the image by adjusting the size of these singular values. Finally, the two-dimensional image embedded with the watermark is back-projected. The normalized correlation coefficient value of the proposed algorithm is higher than that of the traditional algorithm at different rotation angles. In terms of watermark embedding capacity, the bit rate (Bits Per Pixel, BPP) of the proposed algorithm reaches an average of 0.93, which is higher than 0.754 of the traditional algorithm, and the peak signal-to-noise ratio (Peak Signal-to-Noise Ratio, PSNR) value is between 40–62.9 dB, which is much higher than 25.4–40 dB of the traditional algorithm, reducing the impact of watermark embedding on image color. The watermark algorithm based on 3D scanning technology proposed in this paper has achieved remarkable results in improving the robustness and invisibility of watermarks, providing a new solution for copyright protection and data security of digital images.