The multi-scale image analysis and computer vision techniques based on nonlinear PDE models are discussed in this chapter. The results described here illustrate that many effective multi-scale analysis solutions for various tasks can be achieved by using nonlinear diffusion-based models. Some nonlinear PDE-based scale-space representations are created and used by the high-level feature extraction components of several image analysis techniques proposed by us. Thus, some anisotropic diffusion-based multi-scale texture recognition frameworks are described in the first section. Then, the content-based image recognition using nonlinear PDE-based scale spaces is discussed in the second section. The nonlinear diffusion-based multi-scale image indexing and retrieval solutions are presented in the final section.