INTRODUCTION TO DIGITAL IMAGES Image Definition A digital

INTRODUCTION TO DIGITAL IMAGES

Image Definition A digital image is a numeric representation (normally binary) of a two-dimensional image. Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images also called bitmap images.

Vectors Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent images in computer graphics.

Rasters It is a data structure representing a generally rectangular grid of pixels

Black To White 0 26 52 78 104 130 156 182 208 234 255

Gray. Scale Image

Primary Colors For human applications, three primary colors are usually used, since human color vision is trichromatic

Pixel In digital imaging, a pixel or picture element is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled.

Channels Pixels are made of combinations of primary colors. A channel in this context is the grayscale image of the same size as a color image, made of just one of these primary colors.

Digital Image Formal Definition An image may be defined as a two dimensional function f(x , y), where x and y are spatial coordinates and the amplitude f at any pair of coordinates is called the intensity or gray level of the image at that point.

Image Depth 1 bit 2 bit 4 bit

IMAGE DEPTH (contd. ) 8 bit 24 bit

IMAGE AS A MATRIX Lets Move To Matlab

Commands imread(‘image filename’) – Loads image as a matrix imshow(‘variable’) – Shows the image in the Matlab image viewer