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Home , Bitmap, File format, GIF, JPEG, Vector graphics, Windows Metafile

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ESTIMATED TIME Image Types

HOURS

SOURCE: ©PHOTODISC Objectives INTRODUCTION ● You will become familiar Whether a finished project is in a visual or with terms related to image file types. printed format, its impact is only as good as the image it pro- ● You will understand the duces. Many factors go into determining how best to produce difference between painting the image you need. In this chapter, you will explore some of and drawing programs. these factors and learn to decisions that will help you in ● You will understand the selecting the best possible image format for your projects. difference among file types. This knowledge is essential for Amelia Sandefer, who must be ● You will identify able to make decisions in her job as an insurance advantages and investigator. She visits homes that have been damaged or disadvantages of file destroyed by accidents and uses a to record types. what she finds. She must also create simple drawings of her findings to attach to her reports for others to . Since she only has a rather than a high-speed connec- tion, she must keep her file sizes small to speed transmission.

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Figure 2.1 images are the most Figure 2.2 Vector images are smoother common file format used in image than and print without jagged management. edges.

A (picture element) is a representation of a specific color at a specific PAINTING VERSUS DRAWING location in a matrix or grid. A rectangular collection of Many programs are available for creating and managing can produce an image on a images. Programs often used by businesses are Paint, screen or on a , Macromedia Fireworks, Jasc Paint Shop Pro, printed page. , and Macromedia FreeHand. Image management programs are of two types: painting and draw- ing. Paint programs create images by using pixels (picture elements). Pixels are small squares (usually) with each pixel assigned a color (see Figure 2.1). Drawing programs create images by using mathemati- cally defined lines and that are treated as individual objects within the images (see Figure 2.2). Although paint programs are often easier to use, drawing pro- grams give higher-quality results. Some image management pro- grams such as Photoshop and Paint Shop Pro combine both painting and drawing options within a single program.

IMAGE FORMATS OR FILE TYPES THE ETHICS OF GIF LICENSE Image programs save with specific extensions indicat- In 1994, CompuServe Inc., and Corporation, the developers ing the file format. The extension of the GIF file format, announced their intention to require that all is shown by two to four letters commercial software companies using GIF compression in their following the dot in the name of programs pay licensing fees. This announcement caused a a file. For example, if a document considerable stir and resulted in the development of PNG file is named picture.jpg, “picture” is formats that were royalty-free. The average business user is the name of the file and “.jpg” is unaware that a licensing fee is required because it is paid by the the extension indicating the file software company. It is a good reminder, however, that not only format. are software programs protected by but so are the You may not be able to see the products created using those programs. extension name unless you have

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enabled this option in the Folder View. Go to My Computer and the tag">C: drive. Choose View/Tools (depending on your operating sys- tem), Folder Options and click the View tab as shown in Figure 2.3. Remove the check from Hide file extensions for known file types check box. (It is also possible to show or hide file extensions in Mac OS X.) Each image management program has a file format specific to that program, called its native or default format. For instance, Paint Shop Native refers to the file format Pro automatically saves images as .psp. Adobe Photoshop saves in which a particular graphics images as .psd. Generally, an image should be saved in its original program automatically saves or native format to use as an archive or backup of that image. By an image. doing this, you can open, edit, and then save the image in a different format without losing any quality. This is an important step in the creation of an image. Once a copy of the image has been saved in its native format, you can change to another file format by using the drop-down arrow next to the Format or Save as box, as shown in Figure 2.4. From the list that appears, you can then choose the appropriate file format. Different file formats are appropriate for different situations, so it is important to understand the distinctions between the various file for- mats. For example, some programs can only import graphics with specific file formats. Some images look better saved as one format over another, and some images need to be small in order to load quickly on the Internet. Knowledge of file formats enables you to make the best choice.

SOURCE: © 98 SOURCE: ©MICROSOFT WINDOWS 98 Figure 2.3 To see extensions, click on the radio button Figure 2.4 Once an image has been saved in native format, box indicated by the arrow. choose Save as and click on the drop-down arrow to select another format.

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PAINTING PROGRAMS

Painting programs (or paint programs) create bitmap images made of pixels. Each pixel has a defined color, size, and place in the image. The sharpness of the image is determined by the density of the pixels, and this density determines the resolution. Resolution is defined as A bitmap is a graphic created dots per inch (dpi) or by the numbers of pixels in rows and columns by using pixels. (640 480). The higher the resolution, the better your image will Resolution is the density of appear or print out but the larger the file will be. pixels in an image. Amelia has learned that sometimes it is important to save her digi- tal images in the highest possible resolution if she knows that others will want to print a large color version. She also knows that often all that is necessary is an image that can be printed on a black-and-white laser . For example, recently she needed an overall picture of a home that had been hit by a careless driver. She knew that a quick low-resolution shot of the damaged brick wall would serve her pur- pose. At the same time, though, she needed a detailed picture of the interior damage. One of the most common types of bitmapped images is a BMP (Bitmap) file. A BMP image is usually used in word processing docu- ments. BMP file sizes are often quite large, even though they are usually limited to 256 colors because they are not compressed as some other for- mats are. BMP files work well in programs that require the Microsoft Windows . A bitmap file type that works well in all environments is TIF or TIFF (Tagged Image File Format). Like BMP files, these files are quite large and are often used in print documents. TIFF files are not compressed and can show 16 million colors. Many scanners produce images as TIFF files, and some digital cameras can save in TIFF format as well. The file formats most often used for Web pages are GIF (Graphics Interchange Format) and JPG or JPEG (Joint Photographic Experts Group). GIF, pronounced with either a hard or soft “G,” is an image file format developed by CompuServe. Because use only 256 col- ors, the file sizes are quite small. GIFs are used to create line draw- Compression in graphic files is ings, images with transparent backgrounds, and animated figures. the process of reducing the size Because photographs require greater , they lose much of of the image. their quality if they are saved as GIFs. does not The time it takes to download a graphic on the Internet depends on change any pixel data. the size of the file. To improve download speed, several reduces the (sequences of steps to perform a function) have been written to size of a file by removing pixels reduce or the size of the file. The two types of compression that are not essential. are lossless and lossy. Lossless compression reduces the with- displays an image out losing any pixel . Lossy compression changes some on a Web page in stages until pixels while making the file size smaller. The main drawback of a the image has reached its full lossy is that the greater the compression, the poorer the resolution. quality of the image. In business image management, it becomes Noninterlacing renders an important to balance quality with file size. image from top to bottom until GIF compression is lossless using the LZW (Lempel-Ziv-Welch) for- the image is complete. mula, named for the developers. The two versions are 87a and 89a. Most users find 89a to be the best choice because it allows .

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A second consideration when choosing a GIF is interlaced or nonin- terlaced. Interlaced images load onto a Web page in stages, with the first image appearing at a minimal resolution, so the viewer can begin to see part of the picture even before it is completely loaded. At intervals, the picture reloads until the maximum resolution is reached. Noninterlaced images build from the top down until a complete image appears. Inter- lacing slightly increases file size, so it should be limited to large images that take a long time to download. Both Photoshop and Paint Shop Pro provide version options and interlacing choices. JPG or JPEG (pronounced “jay-peg”) is another file type. Using up to 16 million colors, JPG images repro- duce the quality, color, and detail found in photographs or graphics using blends and gradients. Most digital cameras save photographs as JPGs to conserve memory space on the camera’s storage device. The JPG compression formula allows you to choose the amount of compression you want, so you can decide at what the matches your Job Search Skills needs. It also allows you to choose between standard and progressive encod- The first step in finding the job that’s right for you ing, much as with interlacing for GIFs. is to target specific jobs and careers. Decide what A third choice for use on the Internet is you want—not just now but five or ten years into the PNG (Portable Network Graphics) for- the future. Have a career plan. One way to know mat. It retains all 16 million colors and has what you want is to try out a wide range of jobs some valuable features, but it is not sup- through part-time work, volunteering, and so forth. ported by all Web browsers. Then research potential employers that can offer Amelia has learned to save her images in you the kind of job or career you seek. TIFF format and then to convert them to the Perhaps the most important part of the job format that best serves her purpose. This way search involves simply talking with people. Tell she knows that she can always return to the everyone you meet you’re in the job market; you original and create a copy in a different format might make an important contact. Develop a net- without losing quality. This came in quite handy work of people who work in your field of interest. last week when she was asked to submit a pic- By critiquing your résumé and asking you ques- ture she had taken of a tornado-destroyed home. tions about yourself and your goals, your contacts The corporate office wanted to use her picture in can help you sharpen your résumé and interview- their publication and needed the highest quality ing skills—key components in a successful job possible. Her TIFF version met their needs and search. Be sure to send acknowledgment letters she was pleased to see her picture featured the to everyone you talk with; this builds your credibility following month. and sends the message that you’re a professional who is serious about your career. Above all, be persistent! DRAWING PROGRAMS Digging Deeper: Research some local - related companies and develop a list of people Drawing programs create images made of within the companies you might approach for a mathematically defined lines and curves, or brief informational interview. Arrange and follow vectors. An advantage of over through with an interview. Discuss your impres- bitmap images is that regardless of how much sions in class. the image is enlarged or reduced (called

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scaling), the quality remains the same. A vector graphic is smoother than a bitmap graphic because the image is mathematically derived for each output device. Once a vector graphic is completed, it can be converted to a bitmap image. (Another name for a bitmap is raster, so this process is called rasterizing.) Vector graphics are converted to bitmap images for use on A vector is an image created the Internet. Shockwave Flash images and are vector by using a series of graphics. Vector graphics are smaller in size than bitmaps, but they are mathematically defined lines limited because they cannot show gradations of colors as bitmaps can. and curves rather than pixels, The most common native vector file formats are CDR for - making the image easier to Draw, AI for Adobe Illustrator, FH for Macromedia FreeHand, SWF resize or scale. for Shockwave Flash, and WMF for . EPS (Encapsu- lated PostScript) is a general-purpose vector file format that has both the vector image data and a screen in the same file. It is most commonly used for printing purposes. Amelia finds drawing programs very helpful in her work. She uses a vector program to create sketches of the details that might be necessary to supplement her reports. She likes the fact that she can modify length and width of lines even after completing a drawing. In her last report, Amelia added a drawing showing the of the automobile from the street to the wall of the home that was struck. She added details such as specific measurements and estimated speed of travel. These kinds of details have made her information well respected by her employer.

SUMMARY

In this chapter, you have learned about file formats and their pur- poses as shown in the chart below. Image file types can be divided into two groups: painting programs and drawing programs. Exten- sions for the most common painting file formats are .bmp, .tif, ., .jpg, and .png. Extensions for the file formats used for the Web are .gif, .jpg, and .png. Extensions for the most common drawing file for- mats are .cdr, .ai, .fh, ., and .wmf. The EPS file format, with the extension .eps, is a general-purpose vector file with a bitmapped pre- view. It is important that you understand the difference between file formats so that you can decide which ones will best meet your needs.

File Type of Format Stands for Extension Program BMP Bitmap .bmp Painting TIFF or TIF Tagged Image File Format .tif Painting GIF Graphics Interchange Format .gif Painting JPG or JPEG Joint Photographic Experts Group .jpg Painting PNG Portable Network Graphics .png Painting PSD Photoshop Document .psd Painting JASC Jasc Paintshop Pro .psp Painting CDR CorelDraw .cdr Drawing AI Adobe Illustrator .ai Drawing FH Macromedia FreeHand .fh Drawing SWF Shockwave Flash .swf Drawing WMF Windows Metafile .wmf Drawing EPS Encapsulated PostScript .eps Drawing

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REVIEW

Answer the following questions on your own computer. 1. What does a file extension look like? 2. What image management programs are often used by businesses? 3. What are the two types of image management pro- grams, and how are they different? 4. What is a native format? 5. What is a bitmap image? 6. List four types of bitmap images. 7. Why are images compressed? 8. What is the difference between lossy and lossless compression? 9. What is an interlaced image? 10. Why might you want to use an interlaced image? 11. In what format do most digital cameras save images? 12. Why is the PNG format not used more often? 13. What is the advantage of using a vector graphic? 14. Name three native vector file formats and one general-purpose file format. 15. What company developed the GIF format, and what did the developer require beginning in 1994?

DISCUSSION

1. Explain the difference between a vector and a bitmap. 2. Which file format is the most versatile? Why? 3. Why are photographs saved in JPEG format if they are to be used on the Internet? 4. Why is it important to understand file extensions? 5. Was CompuServe correct in its decision to charge a licensing fee? Why or why not?

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USE YOUR KNOWLEDGEREVIEW

1. Use the table function in a word processing document to create a chart listing the advantages, disadvan- tages, and uses of all the file formats discussed in this chapter (see the chart that follows the summary). 2. Use a painting program to create a rectangle filled with color. Save the image in at least six different file formats (such as native, BMP, TIF, JPEG, GIF, and PNG). Look at the properties of each file and record, in the table you created in question 1, the size of each file. 3. Use a drawing program to create an image. The image should be a filled rectangle similar to the one created in step 2. Save the image in at least three different file formats (e.g., native, EPS). Look at the properties of each file and record in the table the size of each file. 4. Keeping in mind the advantages, disadvantages, and uses of each file format, choose one file format and a slogan advertising the file format and its use- fulness. Keep the slogan to eight words or fewer.

FURTHER EXPLORATION

1. Survey your favorite Web sites (at least ten) to deter- mine what file formats the sites are using for their images. To determine the type of file format, right- click on the image and choose Save Picture As. The Save as type box will indicate the extension. 2. Create a chart showing the address of each site and the number of each type of image file used on each site. Observe and record which were interlaced and which were noninterlaced. 3. Do you disagree with the sites’ choices of file formats? How long did it take for pages to load? What can you suggest they do to increase the speed at which their pages appear? Write an explanation summarizing your comments.

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