Transparency Rules
By Lynda Weinman
It's been over a year since I last addressed transparency in my column. (See Web Techniques, July and October 1997.) It never hurts to review the basics every year or so <grin>, and since I'm especially impressed with ImageReady as a transparency editor, I'll share some of my favorite new techniques using that tool.
Most of us don't think about the fact that computer images are always stored in a square or rectangular format. It doesn't matter if you make a graphic on a transparent layer in Photoshop, ImageReady, Fireworks, or any other image editor; once it's saved and reopened by any other program it will be displayed within a rectangle. What's wrong with rectangles? Nothing, except they can get mighty boring and predictable after a while.
The Web especially suffers from an abundance of rectangular shapes. The browser window is a rectangle, frames are rectangles, and buttons and other graphics are often rectangles too. I call this problem "rectangle-itis." Too many rectangles on a page can make your visitors feel boxed in and claustrophobic.
One solution to the rectangle problem is to learn how to use transparency for the Web. Transparent graphics include masks that obscure or reveal parts of an image, creating the illusion of an irregular shape. Of the two most popular Web image formats -- GIF and JPEG -- GIF is the one that enables transparency. Therefore, in order to create irregularly shaped Web images, you must either make GIF images, or you can learn to fake transparency with the GIF or JPEG format, which is easiest of all.
