Hyperspectral and multispectral images do not consist exclusively on relevant information about presence and absence of chemical compounds. Depending on the technique chosen for image acquisition, equipment, experimental/environmental conditions, among others, a variety of unwanted information such as physical phenomena or random/systematic noise will be also present in the data. These variations can be of chemical or physical nature and will generate basically two types of distortion, geometric and spectral distortions. This chapter shows the main distortions related to hyperspectral and multispectral images along with their sources of variation and how to handle them.