Computational Imaging and Partial Differential Equations
Chang-Ock Lee · 2014
Digital images are generated through quantisation and data extraction from analog images for the real world by image capture devices such as a digital camera. The basic idea is to introduce a regular grid to the analog image and to assign a natural number 0 ∼ 255 for each square of the grid, which is called a pixel. A numerical value in each pixel represents the brightness or the average of gray-level of the image in the square. Sometimes, it uses multiple channels, for example, in the case of a colour image, three channels red, green, and blue are used. Another important aspect in the digital image is the resolution, which indicates the compactness of the grid. The higher resolution the digital image has, the closer it is to the real world.