VIEWS: 26 PAGES: 4 CATEGORY: Energy & Green Technologies POSTED ON: 8/30/2012
Introduction to compression techniques,Vector Graphics and Raster Graphics Difference,Compare and Contrast Vector Vs Raster?
Compare and Contrast Vector Vs Raster? In computer graphics, a raster graphics image, or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats (see Comparison of graphics file formats). A bitmap corresponds bit-for-bit with an image displayed on a screen, generally in the same format used for storage in the display's video memory, or maybe as a device-independent bitmap. Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics. "Vector", in this context, implies more than a straight line. Vector graphics is based on images made up of vectors (also called paths, or strokes) which lead through locations called control points. Each of these points has a definite position on the x and y axes of the work plan. Each point, as well, is a variety of database, including the location of the point in the work space and the direction of the vector (which is what defines the direction of the track). There are instances when working with vector tools and formats is the best practice, and instances when working with raster tools and formats is the best practice. There are times when both formats come together. Vector Graphics and Raster Graphics Difference Word processors and spreadsheet or presentation applications, although suitable for creating files for office or Internet use, are not recommended for creating digital art for print. Microsoft Office applications are included in this group. In some cases, however, such files may be converted so as to enable use. Compare Types of Images Categorizes Vector Images Raster/Bitmap Images Vector graphics are resolution Raster graphics are resolution independent. dependent. They can be scaled up or down without any loss of quality. They cannot be enlarged without Resolution losing image quality. Vector images are defined by math, not pixels. The resolution of a raster image or scanned image is expressed in terms of the dots per inch or dpi. Vector images are composed of Raster images are composed of objects not pixels. pixel, so color of each Dots or Pixels. Easier to change the color of individual objects without complexity of colors and try to Color worrying about individual pixels. change colors, and you can see the biggest disadvantage of editing and Coloring vector images is much manipulating raster images easier than coloring bitmaps. Common Vector image formats : Common raster image formats : EPS (Encapsulated PostScript) BMP (Windows Bitmap) WMF (Windows Metafile) PCX (Paintbrush) AI (Adobe Illustrator) TIFF (Tag Interleave Format) File CDR (CorelDraw) JPEG (Joint Photographics Expert Formats DXF (AutoCAD) Group) GIF (Graphics Interchange SVG (Scalable Vector Graphics) Format) PLT (Hewlett Packard Graphics PNG (Portable Network Graphic) Language Plot File) PSD (Adobe PhotoShop) CPT (Corel PhotoPAINT) Popular Vector Editing Popular Bitmap Editing Programs : Programs : Adobe Photoshop Adobe Illustrator GIMP CorelDRAW Microsoft Paint Editing Freehand Corel PhotoPAINT Program Inkscape Serif DrawPlus Xara Xtreme 2.E-Mail the One Page Description About Compression Technique? Introduction to compression techniques Compression is the reduction in size of data in order to save space or transmission time. For data transmission, compression can be performed on just the data content or on the entire transmission unit (including header data) depending on a number of factors. JPEG, Motion JPEG and MPEG are three well-used acronyms used to describe different types of image compression format. But what do they mean, and why are they so relevant to today’s rapidly expanding surveillance market? This White Paper describes the differences, and aims to provide a few answers as to why they are so important and for which surveillance applications they are suitable. When an ordinary analog video sequence is digitized according to the standard CCIR 601, it can consume as much as 165 Mbps, which is 165 million bits every second. With most surveillance applications infrequently having to share the network with other data intensive applications, this is very rarely the bandwidth available. To circumvent this problem, a series of techniques – called picture and video compression techniques – have been derived to reduce this high bit-rate. Their ability to perform this task is quantified by the compression ratio. The higher the compression ratio is, the smaller is the The basics of compression Compression basically means reducing image data. As mentioned previously, a digitized analog video sequence can comprise of up to 165 Mbps of data. To reduce the media overheads for distributing these sequences, the following techniques are commonly employed to achieve desirable reductions in image data: > Reduce color nuances within the image > Reduce the color resolution with respect to the prevailing light intensity > Remove small, invisible parts, of the picture > Compare adjacent images and remove details that are unchnaged between two images The first three are image based compression techniques, where only one frame is evaluated and compressed at a time. The last one is or video compression technique where different adjacent frames are compared as a way to further reduced the image data. As a result of these subtle reductions, a significant reduction in the resultant file size for the image sequences is achievable with little or no adverse effect in their visual quality. The extent, to which these image modifications are humanly visible, is typically dependent upon the degree to which the chosen compression technique is used. Often 50% to 90% compression can be achieved with no visible difference, and in some scenarios even beyond 95%. Latency Compression involves one or several mathematical algorithms that remove image data. When the video is to be viewed other algorithms are applied to interpret the data and view it on the monitor. Those steps will take a certain amount of time. That delay is called compression latency. The more advanced compression algorithm, the higher the latency. When using video compression and several adjacent frames are being compared in the compression algorithm, more latency is introduced. For some applications, like compression of studio movies, compression latency is irrelevant since the video is not watched live. In surveillance and security using live monitoring, especially when PTZ and dome cameras are being used, low latency is essential. 3.Prepare the Table for File Types Including Relevant Details as Shot Name of Extension ,Descriptor of Extension, Compression Types and Proprietorship? Details as Shot Name of Descriptor of Extension Compression Types and Extension Proprietorship (JPEG) JPG is optimized for photographs and Joint Photographic Experts similar continuous tone images that contain many, many colors. It can Lossy Compression Group achieve astounding compression ratios even while maintaining very high image quality (TGA) All values are little-endian; field and TARGA subfield numbers are per Version 2.0 of the specification. Version 2 added the extension area and Raster image file footer. The developer area exists to store application-specific information (TIFF) It is, in principle, a very flexible format that can be lossless or lossy. The Tagged Image File Format details of the image storage algorithm Lossy Compression are included as part of the file. (PNG) This page is intended to provide an explanation of some of the features of Portable Network the PNG format for non-technical users. Graphics Lossless data Compression As such, it doesn't emphasize PNG features like freedom from patents; those are more of concern to developers (BMP) The simplicity of the BMP file format, and its widespread familiarity in Bitmap Windows and elsewhere, as well as the fact that this format is relatively well documented and free of patents, makes it a very common format that Lossless data compression image processing programs from many operating systems can read and write. (GIF) GIF is the abbreviation of Graphics Interchange Format. It was originally Lossless data compression Graphics Interchange developed by CompuServe (an on-line Format service that was pretty successful in the early nineties). ( PICT) PICT is a graphics file format introduced on the original Apple :Parliamentary Information Macintosh computer as its and Communication standard metafile format. It allows the Technology interchange of graphics (both bitmapped and vector), and some :both bitmapped and vector limited text support, between Mac applications, and was the native graphics format of QuickDraw.
Pages to are hidden for
"Introduction to compression techniques"Please download to view full document