2. Chapter 2 File Format

3. Objectives (1 of 2) Identify the difference between vector based graphics and bitmap-based graphics Clarify bitmap and vector graphic format Identify bitmap and vector program

4. Introduction There are two basic classes of graphic file formats: Vector graphics use lines--not dots--to describe images. Bitmap graphics (raster graphics) are collections of dots (pixels) that fit together to make up an image

5. Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical equations, to represent images in computer graphics. primitivespointslinescurvespolygonimages computer graphics Vector-based graphics

6. Vector Vector graphics are good choices for any original drawings or illustrations that you create on the computer because they scale more easily and smoothly than bitmaps do Your main consideration in choosing a vector file format is portability among software applications and operating systems.

7. AI (Adobe Illustrator) files are actually EPS files in disguise. If you use Illustrator (even on multiple platforms) this is a safe choice, but the portability to other software packages is iffy to poor. EPS (Encapsulated Postscript) files are similar to, but somewhat more portable than AI files. EPS files are great for Macintosh or UNIX, but often problematic on Windows machines or on computers that do not have a PostScript printer installed (although workarounds do exist).

8. WMF (Windows MetaFile) If you're using only Windows systems and have no need to maintain portability with other platforms, the WMF format is a good choice. CGM (Computer Graphics Metafile) is a file format for 2D vector graphics, raster graphics, and text.Computer Graphics Metafilevector graphicsraster graphicstext SVG (Scalable Vector Graphics) is an open standard created and developed by the World Wide Web Consortium to address the need (and attempts of several corporations) for a versatile, scriptable and all-purpose vector format for the web and otherwise.Scalable Vector Graphicsopen standardWorld Wide Web Consortium scriptable

9. Vector Editing Programs Adobe Illustrator CorelDraw Macromedia Freehand Macromedia Flash

10. Resolution independent Key Points on Vector Images Scalable No background Cartoon like Inappropriate for photo realistic images

11. A representation, consisting of rows and columns of dots, of a graphics image in computer memory.columns dotsgraphicscomputer memory The value of each dot (whether it is filled in or not) is stored in one or more bits of data. storedbitsdata For simple monochrome images, one bit is sufficient to represent each dot, but for colors and shades of gray, each dot requires more than one bit of data.monochrome The more bits used to represent a dot, the more colors and shades of gray that can be represented. Bitmap – based graphics

12. Example…

13. In general, a file format is chosen based on the following: Color depth: Bitmap file formats offer a range of color depth support. Compression: Uncompressed bitmap files can easily be huge, so you will likely want to choose a format that supports compression. Compression can be lossless, in which all of the information in the original bitmap is retained, or lossy, in which some information (subtle color shifts, for example) is discarded to obtain a smaller file size.

14. Transparency: Some graphic formats--notably PNG and GIF--support transparency, which allows you to replace the background color of an image and thereby get rid of distracting details and bring focus to the main part of the graphic. Portability: Portability refers to how easily you can open, modify, and view the files using different operating systems and software.

15. Bitmap File Formats BMP GIF JPEG, JPG PICT PCX TIFF PSD (Adobe Photoshop)

16. The PNG (Portable Network Graphics) file format was created as the free, open-source successor to the GIF.Portable Network Graphics This format is recognized by the newer Web browsers, provides good, lossless compression, supports transparency on the Web, and supports unlimited colors. TIFF (Tagged Image File Format) format is a flexible format that normally saves 8 bits or 16 bits per color (red, green, blue) for 24-bit and 48- bit totals, respectively, usually using either the TIFF or TIF filename extension.Tagged Image File Format

17. JPEG(Joint Photographic Experts Group) is a compression method; JPEG-compressed images are usually stored in the JFIF (JPEG File Interchange Format) file format.JFIF RAW refers to a family of raw image formats that are options available on some digital cameras.raw image formats GIF (Graphics Interchange Format) is limited to an 8-bit palette, or 256 colors. This makes the GIF format suitable for storing graphics with relatively few colors such as simple diagrams, shapes, logos and cartoon style images.Graphics Interchange Format The GIF format supports animation and is still widely used to provide image animation effects.

18. BMP The BMP file format (Windows bitmap) handles graphics files within the Microsoft Windows OS. Typically, BMP files are uncompressed, hence they are large; the advantage is their simplicity and wide acceptance in Windows programs.BMP file format

19. Bitmap Editing Programs Microsoft Paint Adobe Photoshop Corel Photo-Paint Ulead PhotoImpact

20. Pixel in a grid Resolution dependent Resizing reduces quality Key point on Bitmap Images Easily converted Restricted to rectangle Minimal support for transparency All scanned images and images from digital cameras are bitmaps