Spring Into Linux - page 164

Summary

Spreadsheet applications are widely used. Calc is the spreadsheet application in OpenOffice. It has functionality equal to Microsoft Excel, the leading spreadsheet application.

OpenOffice Calc uses XML to store its documents. XML is a widely used, standard format for storing information in an application-independent format. OpenOffice Calc can read Excel files. Excel can't read OpenOffice Calc files in Calc XML format, but OpenOffice Calc can save documents in Excel format, so that Excel can open them. Calc also reads and writes documents in formats, such as HTML and SYLK, that are general formats, allowing the exchange of spreadsheets among applications.

This chapter describes how to:

Create a spreadsheet
Format cells and pages
Edit a spreadsheet
Use formulas and functions
Save and print spreadsheets

The next chapter discusses the use of graphics on Linux, including drawing, presentation graphics, and pictures. Drawing and presentation graphics are created using the OpenOffice applications Impress and Draw.

Chapter 13. Graphics

Linux has graphics tools for the most common graphics needs:

Pictures : Applications can create and edit graphic files containing digital imagespictures. You can create the pictures in the graphic application or you can edit a picture contained in another file. For instance, you can edit a picture taken with a digital camera or scanned by a scanner. On Linux, the most powerful, full-featured application for creating or editing pictures is the GIMP (GNU Image Manipulation Program). The GIMP offers similar functionality to Photoshop.
Diagrams : Drawings comprised of shapes and lines connecting the shapes . Organizational charts and network diagrams are composed of shapes and lines. Dia is a diagramming program, similar to Visio.
Drawings : Drawings are line art, usually just black and white. Cartoons and logos are commonly made with a drawing application. OpenOffice provides an application called Draw that allows you to create and edit drawings. You can draw directly in OpenOffice documents, as described in Chapter 11. Or, you can export drawings made using Draw in general graphics formats that can be used by other graphics applications.
Presentation Graphics : Creating slides that accompany talks and presentations is a common use of graphics. OpenOffice provides the Impress application for creating slides, comparable to using PowerPoint in MS Office.

The source of your graphics can be original art or drawings that you create. It can also be photographs that you take yourself. If you are using art or photographs originated by someone else, you need to be sure you can legally use the picture. Pictures are copyrighted by default and can't be used without permission.

Archives of pictures are available on the Web. Some pictures need to be purchased; some are free. You need to read the information accompanying any pictures you wish to use. If explicit permission is not provided for public use, you need to get specific permission from the copyright owner.

Graphics File Formats

Graphics files contain information that describes images. An application must be able to interpret graphic formats in order to read or display a graphics file. A text editor or a word processing program can't correctly open a graphics file to produce a picture, although you can insert a graphics file into OpenOffice documents.

The information stored in a graphics file can be in one of several formats, with different purposes. Usually the file has an extension that identifies the type of format. Graphics applications save files with the appropriate extension. However, because Linux recognizes file types by information inside the file, rather than by the extension, when using a Linux application, you might see a message stating that the file extension does not match the file format. Some common formats are shown in Table 13-1.

Table 13-1. Graphics File Formats

Ext	Name	Used for	Advantages/Disadvantages
.bmp	MS Windows bitmap format	MS Windows graphics files	Recognized by most Windows applications.
.gif	G raphics I nterchange F ormat	Web page images: line drawings, cartoons	Better quality than .jpg for images with 256 or fewer colors. Used for animated graphics.
.jpg	J oint P hotographic Experts G roup	Most used type for Web page images: photographs, art	Better quality for photographs than .gif. Smaller file size than .png.
.png	P ortable N etwork G raphics	General graphic images; recognized by browsers	Newer format designed to replace .gif. A universal format with no patent restrictions. Smaller file size than .gif. Better transparency support. No animation support.
.tif	T agged- I mage File F ormat	Popular for graphics exchanged between operating systems	Early type that was designed to be hardware and OS independent. The newer .png format is better suited to exchange in many environments.

You can convert files from one format to another. You can read a file into an application and use Save as to save the file in a different format. If you want to convert quickly, without editing, use the convert command at the command line. For example, to convert an existing .gif file to a .jpg file, use:

convert rose.gif rose.jpg

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Spring Into Linux - page 164

Summary

Chapter 13. Graphics

Graphics File Formats

Table 13-1. Graphics File Formats

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