• An image on film can be understood by a two dimensional light intensity function f(x,y) where

  (1) x and y are spatial coordinates

  (2) the value of f at any point (x,y) is proportional to brightness

  or

  • Gray value of the image at that point. It cannot be stored as such on digital computer.

Digital images:

• A digitized image is one in which spatial and gray scale values have been made discrete. Intensities measured across regular spaced grid in x and y directions which are sampled to 8 bits per point for black and white, 3x8 bits per pixel for color images.
• They are stored as a two dimensional arrays of gray scale values. The array elements are called pixels and identified as x,y coordinates.
• Matrices are perfect tools for mapping, representation of analog images into digital images.

• For example an image that is 800 pixels wide and 600 pixels high can be represented as 600x800 matrix. Each element of the matrix, pixel is used to represent intensity.

  

  Figure 16

• Given a 17” computer screen with resolution of a higher quality image.

  a. 600x 800

  b. 1024x 768

The range of colors or shades of grey that can be represented in an image depend on the amount of space allotted. The process of analog to digital signal conversion is completed by encoding the quantized values into binary spectrum.