Chapter 1 INTRODUCTION TO IMAGE PROCESSING Section – 1.2

Historical Background Images have been used in early languages, providing an easy method of communicating information from one human to next This idea is seen in the drawings created by early cavemen

Historical Background Use of various color paints/inks to record scenes observed by human eye.

Historical Background Commonly an artist accompanied soldiers into battle to record the historic event. Many artists were commissioned to produce paintings of religious events in churches or to produce portrait paintings of royalty

Historical Background During the second half of 16 th century an Italian philosopher, J.B. Porta, made an important discovery by accident. He discovered that light rays penetrating a small hole in a door enclosing a dark room produced an upside down image of the exterior image on a white screen placed behind the door in dark room. This discovery leads to the making of exact oil paintings & Pinhole camera

Historical Background A chemist in france discovered that silver chloride changes its characteristics from clear to black when exposed to light. Two centuries later, J. Alexandre charles, produced simple photographs using paper immersed in silver chloride. But he did not have a way to stop the development process. In 1835, Henry found a method to stop the development process using silver nitrate and sunlight exposure

Historical Background In 19 th century, roll cameras were used as a part of modern photography (black and white images) Various events of US civil war were recorded using similar cameras

Historical Background On May 17, 1861, James Clerk Maxwell presented a color image of a plaid ribbon generated from three red, green and blue photographic plates

Historical Background Motion pictures: Objects moving across the field of view of the eye in faster than 60ms produces an illusion that the object is moving. In 1889, Edison designed a camera that contained a time sequence of images. This research followed by the invention of television

Historical Background The evolution of television era started the phase of image transmission From July 1, 1941, the recommendations sent by National Television Standards Committee were adopted by Federal communications commission for officially starting a commercial television system in US Since then, Images has become a vital part of our daily life

Basics of Image processing Understanding an Image Section – 1.1

What is an image? Image is a two-dimensional function f(x,y), where x and y are spatial coordinates and the amplitude f at any pair of coordinates (x,y) is called the intensity or gray level. When x, y, and f are discrete quantities the image is digital. Video signal is similarly expressed as a sequence of frames f(x,y,t).

Analog v/s Digital Images

Basic Parameters of digital image Pixel: Each pixel represents the color (or gray level for black and white photos) at a single point in the image, so a pixel is like a tiny dot of a particular color Resolution: The more points at which we sample the image by measuring its color, the more detail we can capture. The density of pixels in an image is referred to as its resolution.

Resolution decreased; size kept same

Resolution decreased; size decreased

What is Digital Image Processing? Digital Image Processing concerns the transformation of an image to a digital format and its processing by a computer or by dedicated hardware - both input and output are digital images Digital Image Analysis concerns the description and recognition of the image contents. -the input is a digital image, the output is a symbolic description Computer Vision uses digital electronics to emulate human vision, -including learning, making inferences, and taking actions

Signal v/s image Dimensions? Representation? Amplitude or Intensity?

Basic digital images

What is a grayscale image? Assigning different intensity value to different pixels Example: 8-bit, 16-bit etc Pixel values for 8-bit grayscale image [0,255]

Different scales

Digitization of image (sampling & quantization) Section – 2.4

Image processing system & its key stages Section – 1.4, 1.5