Digital Watermarking is a technique that can be used to embed a known piece of digital data (watermark data) within another piece of digital media (media to be protected) to act as a copyright protection and tracing of illegal copies for the digital media. This work concerned with development of three invisible watermarking techniques and testing their robustness against different attacks (rotation, sharpening, brightness, and JPEG compression). Two image watermarking approaches are developed, the first one embeds the digital watermark data in the spatial domain (by using bit-substitution technique, or position-saving technique), while the second approach embeds watermark data in frequency domain based on DCT technique. In bit-substitution technique, the watermark data is embedded in spatial domain by adding or subtracting a digital pattern to the given image signal. While the Position-saving technique requires no changing in the image signal, only the suitable byte positions that matches the watermark data need to be saved (i.e. kept by the owner). Finally, the watermark data embedded in the DCT domain, where the embedding done into the DCT coefficients after JPEG quantization process. The robustness testing results show that the spatial domain approaches are resistant to rotation, sharpening, and brightness attacks, while Position-saving and DCT techniques are resistant to JPEG compression