This chapter presents image enhancement and image hiding approaches based on linear image fusion (LIF). Most of materials presented here have been published in (Hsieh et al., 2008; Hsieh et al., 2010; Kondo and Zhao, 2006). Apparently, image enhancement, image morphing, and image hiding are completely different technologies for different applications, they can actually be unified under the core of LIF, and this unification can be helpful in other related researches. The reason we use LIF is its simplicity and low computational cost. By our observations, LIF generally has satisfactory performance provided that appropriate source images are used. This motivates the image enhancement approaches presented in this chapter. Note that the intermediate image generated by image morphing, in which LIF plays a fundamental role, can be a way to hide images, an LIF based approach to image hiding is presented in this chapter as well. This chapter consists of five sections. Section 1 gives introductions related to image enhancement and image hiding. Section 2 reviews LIF which is the core for the given applications. Then image enhancement approaches based on LIF are introduced in Section 3. Section 4 presents an image hiding approach based on LIF. Finally, conclusion and future work are mentioned in Section 5.