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Friday, August 7, 2015

Digitize or Input the Image (Analog to Digital)

Digitize or Input the Image (Analog to Digital)

Digitize or Input the Image (Analog to Digital)

With images, most of the data is already in a digital form before
the PC receives it. Cameras and scanners have already taken
the analog image and converted it to digital data during the
process of making an image. There are also digital video cameras
that use the Fire-Wire/i.Link or USB connection to
input digital information directly to your PC.

Analog videos also need to be converted to digital format. These
images include most camcorder images, television video, and
filmed video. As discussed earlier in this study unit, converting
analog input to digital data requires sampling the input and
then digitizing it. The sampling and digitizing is done using
the same method as for sound input, pulse code modulation
(PCM). PCM turns the analog input into a series of 0s and 1s
by sampling the input at set time periods. So in simple terms,
digital video is a sampled form of analog video.

The most common sampling schemes in use today are listed:


Clock Rate
Horizontal Pixels
Vertical Pixels
NTSC square pixel
12.27 MHz
13.5 MHz
PAL square pixel
14.75 MHz
13.5 MHz
17.72 MHz

Technology has progressed to the point that high-quality digital video is available and affordable. An important innovation enabling this growth has been the emergence of high-definition multimedia interface (HDMI), a compact audio/video interface for transmitting uncompressed digital data. A single HDMI link can transfer up to 24 bits of user data at 165 megapixels per second, resulting in a massive bandwidth of nearly 4 Gbps. HDMI can support all existing and planned PC or TV video formats, including:
     SDTV: 720  480i (NTSC), 720  576i (PAL)
     EDTV: 640  480p (VGA), 720  480p (NTSC progressive),
720  576p (PAL progressive)
     HDTV: 1280  720p, 1920  1080i

MPEG-2 and MPEG-4 Files

MPEG files for video are supported by the MPEG-2 and MPEG-4 formats. These formats are commonly used for commercially available movies. Creating videos in these formats and transferring the data onto a DVD can often produce videos playable on your home DVD player. These formats displays a relatively high-quality image in high-end computers, but a jerky image on lower-end computers.
The MPEG video files are of higher resolution (at least 352  240 pixels) and better quality (150 KB/s, 30 fps) than many equivalent files of other formats. The .mpg files require either an MPEG playback video board (hardware assisted playback) or a Pentium MMX CPU or better with an AGP or PCI graphics card and .mpg playback software. With this combination of hardware and software, it’s possible to play commercially available movies on your PCs DVD player if it supports the DVD- or DVD+ standards.
Under the category of MPEG-2 and MPEG-4 videos is DivX™.

Under the category of MPEG-2 and MPEG-4 videos is DivX™. This is a proprietary, MPEG-4 based video compression technology, using its own CODEC, which can shrink digital video to sizes small enough to be transported over the Internet, while maintaining high visual quality. This CODEC can reduce an MPEG-2 video (the same format used for DVD or Pay-Per-View) to ten percent of its original size. Video on regular VHS tapes can be reduced to about one hundredth of their original size. To view a DivX compressed version of the video, you need a media player designed to play DivX encoded content. This player can be downloaded free from
The DivX CODEC is included in this DivX software bundle.
  1. Raster graphics are digital images created or captured (for example, by scanning in a photo) as a set of samples of a given space. A raster is a grid of x and y coordinates on a display space. (And for three-dimensional images, a z coordinate.)
DivX files aren’t compatible with the DVD– or DVD+ file types, and won’t play on stand-alone video players. As with all technologies, the advantages of the DivX CODEC (small file size) need to be weighed against its disadvantages (incompatibility issues).


Quick Time Player
QuickTime is a proprietary multimedia framework developed by Apple, capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. It’s available at no cost for Windows XP, Vista, and Windows 7, etc. QuickTime handles popular audio, graphic, and video formats, including MPEG-2, H.264, and MPEG-4. The Pro version adds features such as full-screen playback, easy editing, production, and the ability to save movies from the Web.

Compress the Data (Still Image Files) 

Still images are usually sent to the PC using the TWAIN API. TWAIN was designed to provide mechanisms for transferring images from the source device to the image application (such as Photoshop). Multimedia applications don’t accept TWAIN files as one of the image file types used in presentations. The image files need to be converted into a compatible format.


This file type is reserved for bit map
This file type is reserved for bit map (often spelled “bitmap”) files. Bit maps define the display space and color for each
pixel or “bit” on the display space. These files aren’t compressed and have a tendency to be quite large. One good thing about .bmp files is that they don’t need to contain a bit of color-coded information for each pixel on every row; they need to contain information indicating a new color only as the display scans along a row. This way an image with large areas of solid color will require a smaller bit map.
Bit maps use the raster graphics method of specifying an image. A raster is a grid that defines how an array of pixels (in x- and y-coordinates) is illuminated, be it monochrome or color. Changing values for one pixel is rather difficult. BMP, GIF, JPEG, and TIFF files are examples of raster graphic files. For this reason, you can’t immediately re-scale a bit map image without losing image quality. In direct contrast to this, vector graphics images are designed to be quickly re-scaled. A vector file (also known as a geometric file) uses commands and mathematical calculations to render an image. Brightness, density, tone, and color are easy to modify. Typically, an image is created using vector graphics editor and then converted to a raster graphic file or bit map for use in a multimedia application.


Enhanced Meta-File (EMF)
Enhanced Meta-File (EMF) is a term for spool file formats used in printing by the Windows OS. When spooled (which stands for “simultaneous peripheral operations online”), a computer document is read and stored (usually on a hard disk) so that it can be printed/processed later.
When a print job is sent to the printer and it’s already printing another file, the computer reads the new file and stores it. Spooling allows multiple print jobs to be sent to the printer at one time.
Vector graphics are digital images created through a sequence of commands that place lines and shapes in a given space. In physics, a vector is a representation of both a quantity and a direction at the same time. In vector graphics, the file is created and saved as a sequence of vector statements.

The EMF format is the 32-bit version of the original Windows Meta-file (WMF) format. The EMF format was created to solve problems the WMF format had printing graphics from some multimedia and graphics applications. The EMF format is device-independent, meaning that the physical dimensions of the original graphic image are maintained on the hard copy despite resolution changes in dots per inch of the printer.
Encapsulated PostScript (EPS)
Encapsulated PostScript (EPS) is the graphics file format used by the PostScript language. PostScript is a printing programming language that describes page appearance.
EPS files can be either binary or ASCII. The term EPS usually implies that the file contains a raster graphics image. In contrast, PostScript files include only the PostScript commands for printing the graphic.

American Standard
Code for Information Interchange (ASCII) is a format for text files on PCs and the Internet.
An ASCII file uses a
7-bit binary number
(a string of seven 0s or 1s) for each alphabetic, numeric, or special character with 128 possible characters defined.


Graphics Interchange Format (GIF)
Graphics Interchange Format (GIF) is the file designator for one of the most common file formats for graphic images on the
Internet. The GIF format uses the LZW compression algorithm.

LZW (named after its three inventors, Lempel, Ziv, and Welch) is an algorithm that can take a large file and store it as a much smaller one. It does this by assigning codes to all of the colors. Instead of storing all of the pixel information, the codes and location are referenced as duplicate color data. Unisys owns this algorithm, and companies that make products that profit from using it (including using the GIF format) need to license its use from Unisys.
The GIF uses a 2D raster image that uses a binary code. There are two versions of the format, GIF87a and GIF89a. GIF89a supports files that enable animated GIF, which is a short sequence of images within a single GIF file.
An Internet committee has developed a patent-free replacement for the GIF, the Portable Network Graphics (PNG) format. 
Meanwhile, many GIF Web site builders continue to be ignorant of, or indifferent to, the requirement to get a license from Unisys for the use of their algorithm. GIF is a loss-less compression algorithm.
Joint Photographic Experts Group (JPEG) standard

This is the term for any graphic image file produced by using a Joint Photographic Experts Group (JPEG) standard. This is a suite of compression algorithms for computer image files. The JPEG scheme includes 29 distinct coding processes. 
To create a JPEG file, choose from this suite of compression algorithms. When you create a JPEG or convert an image from another format to a JPEG, you’re required to indicate the quality of image you want. Since the highest quality results in the highest resolution and largest file, you need to make the trade-off between image quality and file size. There’s a progressive JPEG file that supports fade in Web graphics. JPEG is a lossy compression algorithm.


pcx extension use the PCX file format.
Files that end with a .pcx extension use the PCX file format.
This file format was originally developed by ZSOFT for its PC Paintbrush program. Most optical scanners, fax programs, desktop publishing applications and multimedia programs support the PCX file type.

Portable Network Graphics (PNG)
Portable Network Graphics (PNG) is a file format for image compression that was designed as a replacement for the Unisys-owned GIF. The PNG format was developed by an Internet committee expressly to be patent-free. Like a GIF, PNG files are compressed using a loss-less algorithm (meaning all image information is restored when the file is decompressed during viewing). A PNG file isn’t intended to replace the JPEG format, which is a lossy compression that lets you make the trade-off between file size and image quality during image compression. Typically, PNG file is 10 to 30% more compressed than a GIF file.

The PNG format includes these features:
     You can control the degree of transparency (also called opacity).
     Interlacing of the image is supported.
     You can use gamma correction of the image to “tune” the image in terms of color brightness.
     Images can be saved using true color as well as color palette and gray-scale formats.
The PNG format doesn’t support animation, and files can’t contain multiple images. 

Tag Image File Format (TIFF)

Tag Image File Format (TIFF) is a common format for exchanging raster graphics images between programs. The .tiff or .tif file type identifies a TIFF file. The TIFF format was developed in the 1980s with contributions from the Aldus Corporation (now part of Adobe Software). Microsoft and Hewlett-Packard.
TIFF files can be saved using RGB full color, gray scale, or color palette. They can include files with JPEG or LZW standard run-length image compression.
Windows Metafile Format (WMF)
Windows Metafile Format (WMF) graphics file format is used to exchange graphics information between Microsoft Windows applications and as a print spooler file. WMF files can hold both vector and bit-mapped images.

Displaying Images 

Displaying images on your PC requires application programming that supports the image type you’re attempting to display. 

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