2 Information Processing

1. 2 Information Processing 2.4 The Representation and Processing of Information

2. Information in the Real World • Information can be expressed in different ways: • Text • Graphics or Image • Sound • Video • Animation • And …

3. Text Files and their Properties Some common types of text files: • .doc • .txt • .rtf

4. .doc • A word processing file created in MS Word • It contains Microsoft's proprietary headers and codes and must be opened in Word or software that reads the Word format. • Since Word is used by so many Windows and Mac users, the doc file has become a de facto standard for e-mail attachments over the Internet. * www.techweb.com

5. .doc • Although the page layout is naturally contained in the doc file, if the target computer does not have the same font selected in the original computer, there may be a slight difference in appearance at the other end when another font is substituted. www.techweb.com

6. .txt • Alphanumeric characters that are not in any proprietary file format • A file that contains data made up of ASCII characters. It is essentially raw text just like the words you're reading now. • Program source code, batch files, macros and scripts are straight text and stored as ASCII files. * www.techweb.com

7. .txt • ASCII text files become a common denominator between applications that do not import each other's formats. If both applications can import and export ASCII files, you can transfer your files between them. Almost all word processors import and export ASCII files as well as many database and spreadsheet programs, although the latter may handle only a variation of this format known as comma delimited www.techweb.com

8. .rtf • RTF (Rich Text Format) is a file format that lets you exchange text file between different word processors in different operating systems. For example, you can create a file using Microsoft Word 97 in Windows 95, save it as an RTF file (it will have a ".rtf" file name suffix), and send it to someone who uses WordPerfect 6.0 on Windows 3.1 and they will be able to open the file and read it. • It can carry both text and graphics and even some formats. * www.whatis.com

9. Graphics and Image Files • 2 major types of graphics and image files: • Bitmapped (raster) graphics • Vector graphics * graphicsoft.about.com

10. Bitmap Images • Bitmap images -- also known as raster images -- are made up of pixels in a grid. • Pixels are picture elements; tiny dots of individual color that make up what you see on your screen. • All these tiny dots of color come together to form the images you see. The typical computer monitor has 72 or 96 pixels per inch, depending on your monitor and screen settings. • All scanned images are bitmaps, and all images from digital cameras are bitmaps. * graphicsoft.about.com

11. Bitmap images • When you enlarge the icon, you can clearly see each individual square dot of color. • Note that white areas of the background are still individual pixels, even though they appear to be one solid color. • An icon is usually made up of 32 x 32 pixels * graphicsoft.about.com

12. Print bitmap images • Bitmap images are resolution dependent. • Resolution refers to the number of pixels in an image and is usually stated as dpi (dots per inch) or ppi (pixels per inch). • Bitmap images are displayed on your computer screen at screen resolution: 72 or 96 ppi. However, when printing bitmaps, your printer needs much more image data than a monitor. • In order to render a bitmap image accurately, the typical desktop printer needs 150-300 ppi. If you've ever wondered why your 300 dpi scanned image appears so much larger on your monitor, this is why. * graphicsoft.about.com

13. Resizing • Because bitmaps are resolution dependent, it's difficult to increase or decrease their size without sacrificing a degree of image quality. * graphicsoft.about.com

14. Reduce the size • When you reduce the size of a bitmap image, some pixels must be thrown away. * graphicsoft.about.com

16. Increase the size • When you increase the size of a bitmap image, new pixels are created. • When creating pixels, the software must estimate the color values of the new pixels based on the surrounding pixels. This process is called interpolation. * graphicsoft.about.com

17. Increase the size

19. Question? • What is the difference between resizing a bitmap image with dragging the edges of the image and using software’s resample or resize command?

20. Answer • Using resample or resize command is more accurately called scaling. • Scaling an image does not effect the image permanently. In other words, it does not change the number of pixels in the image. graphicsoft.about.com

21. Answer • However, if you scale a bitmap image to a larger size in your page layout software, you are going to see a definite jagged appearance. Even if you don't see it on your screen, it will be even more apparent in the printed image. Scaling a bitmap image to a smaller size doesn't have any effect; in fact, when you do this you are effectively increasing the ppi of the image so that it will print clearer. graphicsoft.about.com

22. Vector Images • Vector images are made up of many individual, scalable objects. • These objects are defined by mathematical equations rather than pixels, so they always render at the highest quality. • Objects may consist of lines, curves, and shapes with editable attributes such as color, fill, and outline. * graphicsoft.about.com

23. Vector images • Changing the attributes of a vector object does not effect the object itself. • You can freely change any number of object attributes without destroying the basic object. • An object can be modified not only by changing its attributes, but also by shaping and transforming it using nodes and control points. * graphicsoft.about.com

25. Vector images • Because they're scalable, vector-based images are resolution independent. • You can increase and decrease the size of vector images to any degree and your lines will remain crisp and sharp, both on screen and in print. • Fonts are a type of vector object. * graphicsoft.about.com

26. Another advantage of vector images is that they're not restricted to a rectangular shape like bitmaps. Vector objects can be placed over other objects, and the object below will show through . * graphicsoft.about.com

27. Disadvantages • The primary disadvantage is that they're unsuitable for producing photo-realistic imagery. • Vector images are usually made up of solid areas of color or gradients, but they cannot depict the continuous subtle tones of a photograph. • That's why most of the vector images you see tend to have a cartoon-like appearance. * graphicsoft.about.com

28. Even so … • Even so, vector graphics are continually becoming more advanced, and we can do a lot more with vector drawings now than we could just a few years ago. • Today's vector tools allow you to apply bitmapped textures to objects giving them a photorealistic appearance, and you can now create soft blends, transparency, and shading that once was difficult to achieve in vector drawing programs. graphicsoft.about.com

29. Rastering • The most common reason for wanting to convert a vector to a bitmap would be for use on the Web. • At this time, there is not an established and accepted format for vector images on the Web, although things seem to be moving in that direction. • We currently have Flash, a vector format that requires your viewer to have a plug-in, and the SVG format currently being developed will soon become a standard for vector images on the Web. • Due to the nature of vector images, they are best converted to GIF or PNG format for use on the Web. * graphicsoft.about.com

30. Bitmap vs. Vector

31. Metafiles • Metafiles are graphics that contain both raster and vector data. For example, a vector image that contains an object which has a bitmap pattern applied as a fill, would be a metafile. The object is still a vector, but the fill attribute consists of bitmap data. * graphicsoft.about.com

32. Common Graphics and Image File Types • Some common types of bitmapped graphics: • .tif • .jpg • .gif • .bmp • .png • Some common types of vector graphics: • .3ds • .cdr • .emf • .eps • .wmf

33. .tif or .tiff • TIFF (Tag Image File Format) is a common format for exchanging bitmap images between application programs, including those used for scanner images. • One of the most common graphic image formats, TIFF files are commonly used in desktop publishing, faxing, 3-D applications, and medical imaging applications. * www.whatis.com

34. .tif • Developed in 1986 by Aldus Corporation (now part of Adobe Software) • handles monochrome, gray scale, 8-and 24-bit color RGB www.whatis.com and www.techweb.com

35. .tif • TIFF files are compressed using several compression methods. • LZW provides ratios of about 1.5:1 to 2:1. • Ratios of 10:1 to 20:1 are possible for documents with lots of white space using ITU Group III and IV compression methods (fax). www.techweb.com

36. .jpg or .jff • (Joint Photographic Experts Group) Pronounced "jay-peg. • An ISO/ITU standard for compressing still images that is becoming very popular due to its high compression capability. • Using discrete cosine transform, it provides lossy compression (you lose some data from the original image) with ratios up to 100:1 and higher. * www.techweb.com

37. .jpg • It depends on the image, but ratios of 10:1 to 20:1 may provide little noticeable loss. • The more the loss can be tolerated, the more the image can be compressed. • Compression is achieved by dividing the picture into tiny pixel blocks, which are halved over and over until the ratio is achieved. www.techweb.com

38. .gif • (Graphics Interchange Format) A popular bitmapped graphics file format developed by CompuServe. • It supports 8-bit color (256 colors) and is widely used on the Web, because the files compress well. • GIFs include a color table that includes the most representative 256 colors used. For example, a picture of the forest would include mostly greens. This method provides excellent realism in an 8-bit image. * www.techweb.com

39. .gif • There are two versions of GIF. • The original GIF87a was created in 1987, and GIF89a in 1989. • GIF89a allows one of the colors to be made transparent and take on the background color of the underlying page or window. GIF89a also supports animated GIFs, which are GIF sequences displayed one after the other to simulate movement. www.techweb.com

40. .gif • The GIF format and its usage in image-handling software involves licensing or other legal considerations because CompuServe owns the format, and Unisys owns the compression method. • Web users can make, view, and send GIF files freely but they can't develop software that builds them without an arrangement with Unisys www.whatis.com and www.techweb.com

41. .bmp or .dib • A bitmap file (also known as “dump” file) defines a display space and the color for each pixel or "bit" in the display space. • .dib stands for Device Independent Bitmap * www.whatis.com

42. .bmp • A bit map does not need to contain a bit of color-coded information for each pixel on every row. • It only needs to contain information indicating a new color as the display scans along a row. • Thus, an image with much solid color will tend to require a small bit map. www.whatis.com

43. .png • (Portable Network Graphics, pronounced as “ping”) A bitmapped graphics file format endorsed by the World Wide Web Consortium for image compression. * www.techweb.com

44. .png • It is expected to eventually replace the GIF format, because there are lingering legal problems with GIFs. In addition, GIF is a very basic graphics format that is limited to 256 colors (8-bit color). • The PNG format, on the other hand, was developed by an Internet committee expressly to be patent-free. It provides a number of improvements over the GIF format www.whatis.com and www.techweb.com

45. .png • Like a GIF, a PNG file is compressed in lossless fashion (meaning all image information is restored when the file is decompressed during viewing). • A PNG file is not intended to replace the JPEG format, which is "lossy" but lets the creator make a trade-off between file size and image quality when the image is compressed. Typically, an image in a PNG file can be 10 to 30% more compressed than in a GIF format www.whatis.com

46. .png • Unlike the GIF89a, the PNG format doesn't support animation since it can't contain multiple images. • The PNG is described as "extensible," however. Software houses will be able to develop variations of PNG that can contain multiple, scriptable images. www.whatis.com

47. .png • The PNG format includes these features: • You can not only make one color transparent, but you can control the degree of transparency (this is also called "opacity"). • Interlacing of the image is supported and is faster in developing than in the GIF format. • Gamma correctionallows you to "tune" the image in terms of color brightness required by specific display manufacturers. • Images can be saved using true color as well as in the palette and gray-scale formats provided by the GIF. www.whatis.com

48. .png • PNG provides advanced graphics features such as 48-bit color, including an alpha channel, built-in gamma and color correction, tight compression and the ability to display at one resolution and print at another www.techweb.com

49. .3ds • A 3-D graphics file format produced with 3D Studio

50. .cdr • A vector graphics file format produced with Corel Draw