4. Fundamentals of Image Processing

Previously, we defined remote sensing as the art and science of obtaining measurements of objects without direct physical contact. This familiar definition when extended to the topic of the environment can be reworded slightly to focus measurement on the elements and features that characterize the environmental system. Measurement in this context implies the collection of data, numerical symbols that explain how a surface emits or reflects electromagnetic radiation in a characteristic pattern as recorded by a sensor. Data recorded in this manner are nothing more than an array of values that only becomes useful when transformed into some more meaningful information. When applied to activities that describe remote sensing, information forms specialized type of knowledge that is communicated or received concerning a particular circumstance that is of interest to us. Generating information is, therefore, directed and purposeful, following a systematic method that is transparent and repeatable. In this chapter, we will examine the fundamental principles and methods that guide the transformation of remotely sensed data into information. Through this review, we can explore how these methods connect to the analysis and assessment of Earth’s environmental system and gain a clearer understanding of the value of remote sensing technology when applied to this task.