2.01 Investigate graphic image design. Raster Graphics 2.01 Investigate graphic image design.

Raster Graphics Also called bitmap graphics Consist of grids of tiny dots called pixels Have a fixed resolution and cannot be resized without altering image quality Edited in paint programs Teacher Note: Enlarging raster graphics causes them to become pixelated (you can see the individual blocks of colors that make up the image). Notice the pixels Bitmap enlargement Image source: http://graphicssoft.about.com/od/aboutgraphics/a/bitmapvector.htm

Common Raster Formats GIF JPEG BMP PNG TIFF

GIF – Graphics Interchange Format Animation – Standard format for animation on the Internet. Transparency – yes Lossless compression Colors = 256 (8-bit) Most common format for: Text Clip art, animations, icons, logos Simple diagrams, line drawings Graphics with large blocks of a single color Graphics with transparent areas Images displayed on computer screens and on websites. Animated Gif

JPEG – Joint Photographic Experts Group Commonly Used For: Desktop publishing photographs Photographs and natural artwork Scanned photographs Emailing photographs Digital camera photographs Animation – No Transparency – No Lossy compression Colors – 16.7 M (24-bit) High quality but larger file size than a GIF Teacher Note: This format is best for images containing many colors or shades of color. Most digital cameras save the images made with the camera as JPEG files on their memory cards.

BMP - Bitmap Commonly Used For: Animation – No Transparency – No Editing raster graphics Creating icons and wallpaper On-screen display Animation – No Transparency – No Uncompressed 256 colors Large file size - not well suited for transfer across the Internet or for print publications Teacher Note: When editing images, all the changes would be made to the BMP file. When the user is satisfied with the final image, they would then save the BMP as a different file format depending on their intended use of the image. (For example, if it will be used on a website, the images would be saved as a compressed file format such as GIF or JPEG.) By on-screen display, this means displayed on the monitor but is referring to images that are on the desktop computer, not from Internet websites. Icons

PNG – Portable Network Graphics Animation – no Transparency – yes Lossless compression 256 colors Not suited for photographs Commonly Used For: Replacing GIF and TIFF images Online viewing of images See examples at http://graphicssoft.about.com/od/freedownloads/l/blfreepng07.htm Teacher Note: Browser software or image editing program may require the user to download a plug-in before recognizing or opening the file.

TIFF – Tagged Image File Format Animation – No Transparency – No Available in compressed and un-compressed formats Compressed is advised Colors – 16 M (24-bit) Commonly Used For: Storage container for faxes and other digital images To store raw bitmap data by some programs and devices such as scanners High resolution printing Desktop Publishing images Teacher Note: TIFF images have very high quality which is ideal for faxes or printed images, such as those used in desktop publishing. However, this results in a large file size so it is not recommended for images that will be viewed over the Internet.