For all kinds of output devices, such as monitors, printers etc, the most important thing is to show the right information to the user. Pixel is the basic element both on screen and materials printed with. And, as a result pixel processing is the basic technique to make the output correct, precise, and suitable to use on different occasions. Pixel processing solves operations on each pixel of the image, which is for the pixel matrices of that image, so that the image would have different appearance. Ontology is about the exact description of things and their relationships. It is an old study of philosophy from ancient Greece. As the study of artificial intelligence keeps growing, the concept of ontology has been in use more and more in the formalization of knowledge in terms of classes, properties, instances and relations [1]. This paper mainly discusses how to build ontology of pixel processing with OWL. Actually, it is focused on how to describe pixel processing and its functions or operations in an understandable way by computer. With such description, it is possible to improve the development of pixel processing and the sharing of its knowledge both between people and machines. That is from the Natural Language Processing point of view. And also, in the future, it provides a base for intelligent agent to implement pixel processing by understanding such kind of definition and description directly through its knowledge base built up with such ontology. In other words, that may realize the automatic program or program analysis
