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An Introduction to Image Files

Overview. This is an HTML tutorial explaining about cross-platform images suitable for use in a Web document and also an explanation about image transparency. Resources are given for the image software and the Related Links."


Introduction to Image Files

The format of an image to be used on the Web should be a file type that is "cross-platform" which means that several types of operating systems can use that file type. Platforms are operating systems and system configurations such as a Macintosh running OS X on the G4 with dual processors, a PC running Windows XP, or another computer running the Linux operating system. Your images will need to be in a format that all of the computers operating on the Web can use. Popular file formats for Web use are the GIF and JPEG file formats. All graphical browsers support GIF and JPEG file formats.  PNG file formats can only be recognized by some of the graphical browsers but not all of them.
TRANSPARENCY. Transparency is a term used to indicate a GIF89a format file in which a selected color is "taken out" of the graphic file when displayed, so that the browser background shows through the image making the image appear to "float" on the screen.   JPEG files do not support transparency nor do GIF87a images.

Image Software

Creating and manipulating images requires drawing or graphics programs and tools. Paint Shop Pro Adobe Photoshop  and Adobe Illustrator are used by Web designers.
Windows users can use  Paint Shop Pro, Adobe PhotoShopCorelDraw  and other graphics programs.
Macintosh users: Adobe PhotoShop is available for the Macintosh computer and Quark Express is another publishing and photo editing program for the Mac.
Unix platform developers can use the program called xv developed by John Bradley. This program handles the file formats of GIF, PM, PBM, XBM, RAS, JPG, and TIF and translates them into other file formats (the same as listed, plus PS).


Types of Images

The following list contains several of the image formats and one to trick you. Find the fake one. I have used .GIF , .JPG and .BMP images on Web pages.

BMP Microsoft Windows BitMaP file
CUR Microsoft Windows CURsor file
EPS Encapsulated PostScript file
GIF CompuServe Graphics Image Format
HDF Hierarchical Data Format
ICO MS Windows ICOn file
ICON Sun Icon and Cursor file
JPEG (.JPG) Joint Photographers Experts Group file
MPNT Apple Macintosh MacPaiNT file
.NIF Not Image File
PBM Portable BitMap file
PGM Portable Grayscale Map file
PIC PIXAR PICture file
PICT SoftImage PICT file
PIX Alias PIXel image file
PNG Portable Network Graphics
PNM Portable aNy Map file
PPM Portable Pixel Map file
PS PostScript
RAS Sun RASterfile
RGB Silicon Graphics RGB image file
RGBa 4-component Silicon Graphics image file
RLA Wavefront raster image file
RLE Utah Runlength-Encoded image file
RPBM Raw Portable BitMap file
RPGM Raw Portable Grayscale Map file
RPNM Raw Portable aNy Map file
RPPM Raw Portable Pixel Map file
SYNU Synu image file
TGA Truevision Targa image file
TIFF Tagged Image Format file
VIFF Khoros Visualization Image File Format
X Stardent AVS X image file
XBM X11 BitMap file
XWD X Window Dump image file

Related Links



Updated 11 April 2006

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