2.01 Understand Digital Raster Graphics

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 pixilated (you can see the individual blocks of colors that make up the image).

Raster graphics Can support high color depths. Most common type of raster is a digital photograph. Great for adding special effects. Work well for web design. Used to create images for print design.

Raster graphics Native File Formats: file formats that are default file format that are proprietary to a specific program that are generally not meant to be used with other software. Standard File Formats: file formats that can be used with a variety of software programs. Standard file formats are usually created by using the “Save As” command or through exporting. Standard file formats include, but are not limited to: .gif, .jpg, .png, and .tif.

Common Raster Formats PSD JPEG GIF PNG TIFF PDF

PSD – Photoshop document 1.01 Investigate graphic types and file formats. PSD – Photoshop document Native file format for Adobe Photoshop Supports transparency Supports layers, text, and effects Large file sizes. Industry standard for raster graphic editing

GIF – Graphics Interchange Format 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. Standard format for animation on the Internet Supports transparency Lossless compression Colors = 256 (8-bit)

JPEG – Joint Photographic Experts Group Commonly Used For: Desktop publishing photographs Photographs and natural artwork Scanned photographs Emailing photographs Digital camera photographs Does not support animation or transparency Lossy compression. Colors – 16.7 M (24-bit) High quality 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.

PNG – Portable Network Graphics Does not support animation Supports transparency Lossless compression Supports multiple color depths PNG 8 – 8 bit color Small Graphics PNG 24 – 24 bit color Basic Graphics 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 Does not support animation or transparency Available in compressed (lossless) 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.

PDF – Portable Document Format 1.01 Investigate graphic types and file formats. PDF – Portable Document Format Open source, platform independent format that embeds fonts, images, layouts, and graphics Allows choice of lossy and lossless compression Supports 16 million colors Viewable with Acrobat Reader, a free program by Adobe Commonly used for: Sharing files regardless of available software Share files that can be protected from copying or editing Publishing electronic documents and ebooks