Digital image processing

A natural image taken with a camera, telescope, microscope or Another type of optical device displays a continuously different array of colors and shades. Photographs made with film or video images of a camera vidicon tube are a subset of all possible images and contain a wide range of intensity, from dark to light and a spectrum of colors that just about every conceivable hue and Saturation level can contain. Images of this type are referred to as a semitone, as the different tonal colors and hues blend without interruption to generate a faithful reproduction of the original scene.

Continuous tone images are of analog optical and electronic devices, produced the record just image data by several methods, such as a Sequence of electrical signal fluctuations or changes in the chemical Nature of a film emulsion continuously over all dimensions of the image . Change This handles a half-tone or analog image or a Computer, you must first be shown in a computer-readable form or digital format to be converted. This applies to all images, regardless of which the origin and complexity, and whether they be black and white (grayscale) or full color are available. Since gray-scale images to explain a little easier are, they will serve as the primary model in many of the following discussions.

To convert a continuous tone image into a digital format, the analog image divided into individual brightness values ​​by two operational processes that Sampling and quantization, as shown in Figure 1. The analog A miniature representation of young starfish taken with a light microscope presented in Figure 1, point a. After sampling in a two-dimensional array (Figure medicine chest, light levels at various locations in the analog image is recorded and later converted one of the numbers during the process of quantization (Figure 1 (c)). The goal is the image in an array to convert from discrete points that each specific information about brightness and tonal range and include described by a particular digital data value to a precise location can be.

As images are square or rectangular in dimension, as a rule, each Pixels, with the image by digitizing a specific coordinate pair x and y values ​​in a typical Cartesian coordinate system located shown. The X coordinate is the horizontal position or column Location of the pixel, while the y-coordinate of the vertical line number or Position indicates. By convention, the pixel positioned at coordinates (0.0) is located in the upper left corner of the array, while a pixel on (158.350) where the 158th and 350th column are positioned cut would.