Subject : multimedia

1. 
   Define Images
   

1. 
   Write the Use of Transformation Tools
   

1. 
   The ratio of the speed of a light in a vacuum space is measured by RI
   
2. 
   What is the use of TWAIN
   

1. 
   The RGB model is only valid for describing behavior of colored lights.
   

They are categorized into various types.

1. 
   Hard Copy Vs Soft Copy:
   

1. 
   Continuous Tone, Half-tone and Bit one Images:
   

Bitonal Images use only two colors typically black and white and do not use any shades of grey.

is dependent on three factors the nature of light, by interaction of light and matter physiology of human vision. Each factor plays a vital part and the absence of any one would make seeing color impossible.

• 
  Radio wave is used for Long distance.
  
• 
  Gamma wave is used for short distance.
  
• 
  At one extreme of light we can have gamma and radio waves.
  

The second part of the color is human vision. Retina is the light sensitive part of eye and its surface is composed of photoreceptor or nerve endings. These receive the light and pass it along through the optic nerve to the brain. The different frequency gives rise to different color sensations to our eyes.

When ever light waves strike an object part of the light energy gets absorbed and transmitted while the remaining part gets reflected back to our eyes.

The ratio of the speed of a light in a vacuum space is measured by RI (Refractive Index). The object it does not transmit the light is called as opaque object.

Image processing is the name given to the entire process involved with the input editing and output of images from a system.

Image input is the first stage of image processing. It is concerned with getting natural images into a computer system for subsequent work. It deals with the conversion of analog to digital form. It is mainly done using 2 devices.

1. 
   Scanner: It converts the printer images or a document into the digital form.
   
2. 
   Digital camera: It digitizes the real world images similar to a conventional camera.
   

After the images have beam digitized and store as files in the hard disk they are changed to make them more suitable for specific requirements. This step is called editing and involves one or more images called editing software.

Before actual editing process beings an important step called Color Calibration need to be performed to ensure that the image looks consistent when viewed on multiple monitor. After editing the images are usually compressed using mathematical algorithms and saved in specific file formats.

OUTPUT:

This output image is the last stage in processing. It is concerned with displaying the edited image to the user. It can be displayed either in a stand alone manner or as a part of some application like presentation or web-page.

Interface standards determine how data from acquisition devices like scanners and digital camera’s flow to the computer in a efficient way. There are 2 main interface standards.

• 
  TWAIN interface
  
• 
  ISIS(Image and Scanner Interface Specification)
  

One of the important standards developed by HP (Hewlett Packard),Kodak, Aldus etc., which specifies how images acquisition devices such as scanners and digital camera and other devices transfer data to the software application.

It was first released in 1992 and the current version is 1.9 developed in Jan 2000. The TWAIN is used to reflect the difficulties at the time of connecting scanners and personal computers. TWAIN is a software protocol which regulates the flow of information between the software application and imaging devices like scanners.

The main goal of TWAIN is to create multiple flat form support for various types of flatbed scanners, hand-held scanners, image capturing boards, digital camera etc. It provides extensibility and ability to grow with industry needs. It is easy to implement with documentation.

It supports different types of images like BMP, Vector and text etc., It available in the form of a driver from the scanner or digital camera vendor, it is free to use and no royalty is required. It uses four layers of protocol for connecting TWAIN compliant devices the hardware interface element of TWAIN is called Source.

The source manage allows user to select the desire source and for implementation. More than one TWAIN can be connected to the computers. The physical device source the source manager and the application correspond to the four layers of the model.

• 
  Device layer
  
• 
  Application layer
  
• 
  Acquisition Layer
  
• 
  Protocol Layer
  

ISIS developed by the pixel translation and they retain control over its development and licensing. The wider set of features than TWAIN and typically users the SCSI-2 interface while the TWAIN uses USB.

Based on the structure the software modules like image acquisition file conversion, data extraction and file R/W commands has the merit of scalability. The new modules are added without making system wide changes. It interacts with each other through the system of tags and choices.

Two or more ISIS together performs a specific function called the pipe. The ISIS drivers are available for more than 250 scanners.

The device independent color model communicates color information in a way the human eye perceives then and does not dependent on any specific devices like a monitor or pointer. The two device independent color model is

• 
  LAB
  
• 
  HSB
  

The ICC color management system uses the model called CIE L*a*b* model developed in 1976 (Commission International De l’Eclariage). According to CIE sum where between the optical nerve and the brain the retinal color stimuli are translated into different color between light and dark red, green , blue, and yellow.

The CIE L*a*b* indicates these values with 3 axes. Central vertical axes represents brightness (*) whose value run from O(Black) to 100(White) a color cant be both red and green or both blue and yellow because they are opposite to each other.

In each axes the value run from positive to negative. The positive value represents the amount of red while negative values indicate amounts of green. On the b-b axes, yellow is positive and blue is negative. For both axes zero is neutral grey.

The other device independent model used is HSB Model. The concept of Hue Saturation and Brightness to communicate color information. The Hue defines the color itself E.g.: red in distinction with blue or yellow.

The value of Hue axes runs from 0-360º The beginning and ending with red and running through all intermediary color such as green, blue etc..,

This representation is called the color wheel and it represents color in terms of angles. Saturation refers to the degree to which the Hue defines from natural 100 percent. Brightness indicates the level of illumination. Values run from 0% to 100%. Last it forms an ellipsoid.

Most of the color that we see around can be derived from mixing a few elementary colors. These elementary colors are known as Primary Colors. Primary colors mixed in varying proportional produce other color are called as composite colors. Two primary colors mixed in equal proportional produce a Secondary Color. The primary color along with the total range of composite colors they can produce a constitute a color model.

RGB color model is used to describe the behavior of colored lights like those emitted from a TV screen or a computer monitor. This model has 3 primary colors Red, Green, Blue.

Proportional of colors are determine by the beam strength. The electron beam having the maximum intensity falling on a phosphor dot creates 100% of the corresponding color 50% of the color.

Inside the CRT electron beams falling on red, green and blue phosphor produce corresponding color lights. This mixed together in proportion produce composite color. The production of color determine beam strength an electron beams having the maximum intensity falling on a phosphors dots creates hundred percent of the color.

Lower intensity values produce shades of grey. A color present at 100% of its intensity is called Saturated, otherwise the color is said to be Unsaturated. An arbitrary color say orange can be specified as 96% red, 40% Green, 14% Blue.

CMYK Model:

The RGB model is only valid for describing behavior of colored lights. When specifying color of ink on paper we require a different model. If the RGB model was followed the red color with the blue color result in magenta.

The red ink try to absorb the blue light reflected from the blue and similarly the red ink. The result is that no light comes from the mixture to our eye and it looks black. Hence need a new model call the CMYK model. It is used to specify printed colors.

The primary color of the model are cyan, magenta, black, yellow, K stands for the black component. The color of pure cyan, magenta, yellow and black are indicated as 100%. When the ink are mixed with other color the proportion and the saturation of the color decreases.

Mixing cyan and magenta in equal proportion produce blue.

Magenta + Cyan---- Red. Yellow + Cyan ---- Green.

Thus secondary colors of the CMYK model are the same as primary color or RGB. RGB and CMYK model known as complementary Model.

Lab Color Gamut

RGB Color Gamut

CMYK Color Gamut

2. 
   Explain the SCANNER
   

Digitization involves physical devices like scanner or digital camera. The scanner is a device used to convert analog images into digital form. The most common type of scanner for the office environment is called flatbed Scanner.

The paper document to be scanned is placed face down on the glass panel and the scanner is activated using software from a computer to which the scanner remains attached. The traditional way of attaching a scanner to the computer is through an interface cable connected to the parallel port.

Construction and working principles of scanner:

The scanner is activated using software from the computer. The scan head contains source of white light. As the head moves across the paper the light illuminates the paper in the paper the light on getting reflected by the paper image falls on a grid of electronic sensors, through glasses and sensors.

Electronic sensor are called Charged coupled devices (CCD). The CCD is used to convert the light energy to voltage pulses. The strength of the voltage pulse depends on the intensity of the light falling on the CCD. Brighter region gives more light signals. Darker region gives weaker signals.

After complete scan the image is converted in form (Continuous entity) to a discrete form (digital) by voltage pulse. This is called Sampling. The next step quantization represents voltage pulse as binary numbers and carried out by a n (ADC) analog to digital conversion inside a scanner with the software called Scanning Software.

The software decides the number of bits present in the binary representation.

Moving head with light source

This is the most common type in office environment. It looks like a photocopy machine of glass panel on which document to be scan is placed down. Below the glass panel is moving head moves slowly from one end of the documents the other and the light emitted from it is caused to fall on the document get reflect from it and fall on CCD array through a system of mirror repeated on bright and dark. Region of the document, the CDD generated varying voltage signals.

These stores in a buffer and later feed to an ADC. The light is made to fall on small strips of the document at a time. As the head moves on the next row is scanned. The process continuous until all the rows of the document has been scanned.

Text or images on the document is therefore visible to the CCD only because of the light it reflects.

It is used to obtain good quality scans for professional purpose and generally provides a better performance than the flatbed scanner. It consists of a cylindrical drum made out of highly translucent plastic like material. The image to be scanned usually a film is wet-mounted on the drum that is soaked in a fluid. The fluid can be either oil based or alcohol based.

The drum scanner use a PMT (Photo Multiplier Tube) instead of a CCD it is more sensitive than the CCD and more expensive. It works on the principles of photoelectric effect in which absorption of a photo one result on a electron emission.

The multiplier consists of a scaled glass tube contain anode and a number of diodes. Each diode starts to a higher voltage that the previous on hitting each diode. The photo electron will emit additional electrons which accelerate towards the next diodes.

This process continues until the anode reaches the sharp increase in voltage pulse indicating the detection of the photon.

Barcode Scanners:

It is designed specifically to read barcode printed on the various surfaces. A barcode is a machine readable representation of information in a visual form. Barcode use a set of parallel vertical lines whose width and spacing between them is used to encode information. Codes relieve the operator of typing string in a compute, the encoded information is directly read by the scanner.

EAN (European Article Numbering) and UPC (Universal Product Code) are the type of barcode holds the complete information and does not need external database. The light falling on the barcode gets reflected back and it sent to a photoconductor for translating them into electrical impulse. A laser barcode scanner is more expensive than the LED one but is capable of scanning barcodes at a distance of about 25cm. The barcode scammer can either be hand-held or stationary type.

Color Scanning:

The CCD elements (Charge Coupled Devices) are sensitive to the brightness of the light the pixel essentially store only the brightness of the original image is called as luminance. To include color or chrominance 3 CCD elements are sensitive to Red, Green, Blue components of light.

White light reflected of the paper document split into primary colors by a glass prism and made to fall on the CCD sub component.

Light ray splits into RGB

Components

R-CCD Sun-component

G-CCD Sub-Component

Prism B-CCD Sub -Component

The output from each sub component is combined to produce color scanned images. For color scanning the light is split into primary components.

The color digital image pixel needs both human and choroma. This is represented by percentage values. E.g. In a 24 bit image each pixel of the image is divided into 3 parts of 8 bits each to represent the RGB percentage values. This is called RGB Triplet.

The values are often expressed in hexadecimal these are called RGB attributes. To display the image the processor retrieves RGB attributes of all pixels from digital image on the hard disk and sends to the adapter card.

It intercepts these values and converts these back to analog signals. These are sent to the pointer through cable and or used to connect the strength of electron beam .The beam falling on the phosphors produce light and the emitted light are combined together to produce a composite colored light.

The quality of a scan image is determined mostly by its resolution color depth. The scanner resolution of CCD elements inside a scanner. This is measured in dpi (Dots per inch) Scanner resolution is based on 2 factors.

1. 
   Optical Resolution:
   

The scanners are rated the resolution values higher than that of optical resolution. These are called interpolated resolution and basically involves in interpolation process for generating new pixel values.

1. 
   Color Depth:
   

To scan an image the user needs scanning software to be installed in the computer. The software helps to interact with the scanner and set parameter like bit depth and resolution.

• 
  It set the bit depth of image which defines the total number of color and indicates the list of images (Black and White, halftone image, grey scale color).
  
• 
  Set the output path of the image.
  

• 
  Set the file type of the image such as BMP, JPEG, and TIFF.
  
• 
  Adjust brightness and contrast with the help of parameter by dragging the sliders. Change the size of the image by using (scale factor). Where scale factor divided into 2. Uniform scaling denotes the relationship of height and width of the image. And non-uniform scaling allows independent control of height and width.
  
• 
  Adjust color of the scanned image by adjusting RGB Primaries.
  
• 
  Adjust the resolution Value.
  

The digital camera is use to digitize real world images the digital camera also has lens through which the light from the real world object enter the digital camera. Instead of falling on the films it fall on the CCD array similar to a scanner. the voltage pluse from the CCd travel to ADC and converted to binary representation and stores the digital image file.

The digital camera has its own storage facility inside it in the form of a floppy disk. the image cannot be stored as such in the floppy disk as the images occupy lot os space.

So the images are compressed and stored in JPEG format. This is called lossy compression technique. There is a slight loss in the overall images quality. The floppy disk in the digital camera can hold 15 to 25 images. Floppy can be simply taken out of the digital camera and inserted to the computer to copy the image to the computer. The bit depth resolution is default in the digital camera.

ADC

Lens

Object CCD array

Digital camera has software utility in the ROM chip inside it which helps the user to toggle between the camera mode and the play mode. Play mode the user is presented with the menu structure having some of the functionality like displaying all the images, deleting selected images. Camera mode the software takes care of the compression process before storing the images and additionally allows changing some parameters like lighting, color adjustment and special effects.

The number of pixel along the height and width of a bitmap images is called pixel dimension of the image. The display size of an image on screen is determined by the pixel dimension of the image plus the size and setting of the monitor. The file size of an image is proportional to its pixel dimensions.

Image resolution is nothing but a number of pixels displayed per unit. The length of image resolution is usually measured in PPI.

Digital size of an image is measured in kilobytes, Megabytes and gigabytes. This is proportional to the pixel dimension. More pixels produce more details but requires more storage space and process becomes slowly.

It defines number of bits require to store the information and also the total number of colors in the image.

Depending on the way the images are stored on the hard disk. It can be classified as bitmap images or vector images. The Bitmap images are suitable for continuous tone images. The vector images are stored internally as mathematical entities.

The mathematical shapes interpreted by the processors and the graphic controller of a computer and translated into pixel values for displaying on the Screen. Bitmap images are normal images and graphics are represented in vector entities. The bitmap images are generated by scanning analog images using the scanners. Vector images are generated by micro media flash player.

Advantages:

• 
  The vector entities can be scaled to various size without degradation on quality.
  
• 
  The vector images when magnified to larger size leads to increase in distance of pixel.
  
• 
  The bit map images at a certain stage the individual pixels become visible as single color square.
  
• 
  The image takes a boxy appearance with low quality this is called pixelation.
  
• 
  In the vector entities there is no pixelation.
  
• 
  The vector images are compacted and have small file size compare to BMP.
  

• 
  They can be easily animated to maintain crisp look.
  
• 
  The BMP images are bulky large.
  
• 
  The vector images are not able to represent accurately a large number of the color images
  
• 
  This is used to get small charts, logos, and map.
  

A color management system is a collection of software tools designed to reconcile the different color capabilities of scanners, monitor, printer, image setters and printing press to ensure consistent color for the whole printing process.

The color management system was formed by the ICC (International Color Consortium) in order to establish color standard. An ICC color management system has 3 major components,

• 
  Device profiles that defines the color characteristics of a particular devices.
  
• 
  Device independent color space also known as reference color space.
  
• 
  A Color management module that interprets the device profiles and carries out the instruction on what to do with different devices.
  

The set of color displayed by a specific device is known as the color space of the device. A CMS works by determining the color space of each device in a file called device profile.

The device profile are supplied by the manufacture of the device or generated by the parameter obtained from the device. Specialized software are used to obtain the parameters and compile them into a device profile file.

CMM (Color Management Module):

It represents the unique characteristic of each device. When an image is created on one monitor and is displayed on another monitor the difference in the characteristic between the two monitor would change the color of the image. To minimize this second component of the CMs called the Color Management Module.

To translate from one color space to another the CMM needs to map the first color space to a device independent color space and then maps it again to the second color space. For this it need an interpreter, where it is the CMM and Neutral language and it is independent color model.

The image processing software offers wide varieties of way to manipulate and enhance the image. They are categories into many tools..,

• 
  Selection Tools:
  

• 
  Painting and Drawing Tools:
  

• 
  Color Solution Tools:
  

• 
  Gradient Tools:
  

• 
  Clone Tools:
  

• 
  Transformation Tools:
  

• 
  Retouching Tools:
  

• 
  Text Tools:
  

• 
  Changing Image Characteristics:
  

• 
  Filters:
  

• 
  Layers:
  

• 
  Color channels:
  

• 
  Masks:
  

• 
  Alpha Channels:
  

• 
  Anti-Aliasing:(False Presentation):
  

• 
  Dithering:
  

• 
  Indexed Colors:
  

The images may be stored in variety of file formats. Each format depends on the compression type and color depth. In Dos it is very compatible. It supports RGB images, indexed color, gray scale and bit map color models and it does not support alpha channels.

Commonly used to display photo and other continuous tone images of HTML. It supports CMYK, RGB and gray scale. It does not support alpha channels, uses 24 bit format to retain all color information. We can specify the level of compression (1-10). Where 1 stands for high level and 10 stands for low level compression.

This is use to display indexed color images in HTML. It preserves transparency in index color image and does not support alpha channels. It uses 8 bit and compresses solid area of color and used to create animated images. And represent color using the CLUT.

It is designed by Aldus Corporation and Microsoft in 1987. It is used to exchange files between application and computer TIFF is a flexible bit map image format supported by all image editing and page layout application. All desktop scanners scan produce TIFF images. It supports pixel resolution of 48 bit, 16 bit from RGB and can be stored in a number of color models like CMYK , RGB , CIEL-L*A*B. indexed color and gray scale image with alpha channels.

It is used for lossless compression and for display of images on World Wide Web. It supports 24 bits image and produce background transparency without jagged edges. RGB indexed color, grey scale and bit map images without alpha channels.

It is widely used in Macintosh, - OS (Mac) as an intermediary format for transparency images between applications. It supports RGB with single alpha channel and indexed color, gray scale and images with large areas of solid color.

It is designed for system using the true vision video board commonly supported by Ms-DOS. It has 24 bits and 32 bits of RGB.

It is a default file format used in adobe photo shop. It supports all image mode, alpha channels and layers.

Greater the image resolution higher the quality. The image pixels or actually string of binary bits or binary numbers called Logical Pixels. When the image are displayed on the monitor the logical pixels or directly mapped on to the phosphor dot on the monitor called Physical pixels. Two factors are..,

• 
  Monitor Size
  
• 
  Monitor Resolution
  

The monitor resolution in this case is equal to image resolution. when the image is now shown on the screen, the first 72 logical pixels of the image get directly translated to corresponding 72 physical pixels on the monitor. The next 72 logical pixels then translated to the next 72 physical pixels.

An image with pixels dimension of 640*480 would fill up the entire screen. Now if the same image is displayed on a 20 “monitor with a 640 by 480 setting, the image would again fill up the entire screen. If the viewing mode of the 20" monitor is increased to 800 by 600 then the image will copy only a portion of the screen as the available number of pixels is more than that required for displaying the image.

Printer has 2 types of printers used for multimedia content. They are..,

• 
  LASER Printer
  
• 
  INKJET Printer
  

If good quality of image is required the image should have resolution of 300dpi.

Laser Printer is introduced by Hewlett Packard in 1984 based on the technology developed by Cannon. It works similar to photo copier and difference being the light source. The photo copier the page scanned with the bright light. In Laser printer the light source is a laser (Light Amplification by Stimulated Emission of Radiation). They became popular because of the high quality of print and low running cost.

LASER beam

Photoconductor Drum

Charging roll

Cleaning blade Developer roll

Drum rotation

Hot roll

Transfer roll

Transfer roll

(How the LASER Printers Works)

The color printing is produced by using Cyan, magenta and yellow toners in combination with black toner. Four passes through the electron photographic process or performed by generally placing toners on page one at a time or building up the 4 color image on an intermediate surface.



INKJET Printer:

It employs a non impact method meaning that there is no head or hammer striking the paper to produce the print. INK is emitted from the nozzle when they pass over a variety of media’s. The print head scan’s the page in horizontal strips using the motor assembly to move from left to right and to back.

Another motor assembly is used to roll the paper in vertical strips, that strips of a image is printed and the paper moves on ready for the next. Most of the inkjet printer uses the thermal technology for printing. The heat is used to fire ink on the paper. There are three main stages in this method.

Thermal Technology:

The ink is heated to create a bubble until the pressure forces it to burst and hit the paper. Bubble then collapses as the element cools and the resulting vacuum draws ink from the reservoir to replace the ink that was ejected and if is formed by Cannon and HP.

Whatever type of ink is used it must resistant to heat because the firing process is heat waste. By use of this heat in thermal printers create a need for cooling process. This limits the maximum speed of the printer.

PIEZO ELECTRIC:

It was piece of crystals at the back of the ink reservoir storage. The crystals are oscillated to create voltage when electric pressure is given. So to print a dot a current is applied to the piece element and the element is pressured and drops the ink out of nozzles.

• 
  Allows more control over the shape and size of the ink drop.
  
• 
  Tiny fluctuations in crystals allow smaller drops.
  
• 
  Unlike the thermal technology the ink need not be heated and cooled for each cycle.
  
• 
  This saves time and the ink is automatically absorbed.
  

The ink used in the inkjet technology is water based and creates few problems. Some of the earlier inkjet printer was prone to smudging and running. But now, technologies were developed in the ink chemistry.

Oil based ink are used but very costly. Water resistant inks were recently developed inks. The printing quality is comparatively weaker than the Laser.

SUBJECT : MULTIMEDIA

CLASS : II MSC CS

UNIT : I

SEMESTER : 3

STAFF : P.RADHA

UNIT-III

AUDIO