This chapter is from the book
This chapter is from the book
This chapter is from the book
Workshop
In this hour you have covered a lot of ground regarding how to get the best from the Optimize options in Fireworks. Use the following questions and quiz not only to test your memory but also to check that you have understood the concepts involved in image optimization. At the very end are some optional exercises designed to give you ideas on where these techniques can be used.
Q&A
What's the best kind of compression?
There is no universally "best" kind of compression. Different kinds of compression are suited to different kinds of material. Non-lossy compression is better for images where detail is critical. Lossy compression is better for images with many colors or gradients (like photographs) or large dimensions, where detail can be sacrificed for file size.
Why would I ever use BMP or PICT files?
BMP and PICT files do not employ compression and therefore are reliable ways to move images between applications or as backup formats. BMP and PICT files can also be used for system images, such as icons and desktop wallpaper. BMP is the Windows system format; PICT is the Macintosh system format.
What on earth is HTML, and why should I care?
HTML, or Hypertext Markup Language, is the most common method used to compose Web pages. It was developed in the early days of the Internet to format and describe documents for display. HTML files are text files that contain tags to describe the layout. To add an image to a Web page, you insert an HTML image tag that tells the browser where to find the image and where to place it on the page—the HTML file does not actually contain any image files. Fireworks does most of the work for you, but if you're completely unfamiliar with HTML, you may want to pick up a primer, such as Sams Teach Yourself HTML and XHTML in 24 Hours by Dick Oliver.
Quiz
What export format supports 8-bit alpha transparency?
GIF
JPEG
PNG
How does the JPEG format make files smaller?
By approximating image data through lossy compression
By changing the image dimensions to reduce the number of pixels
By employing a 256-color palette to limit color depth
What is the Web 216 palette?
The maximum number of colors displayed on a Web page
The colors considered safe on most systems
The only colors available with the GIF format
Quiz Answers
c.—GIF images support only index transparency. Alpha transparency allows for transparency shading, or graduated levels of opacity, and is available only in the PNG format. JPEG does not allow for transparency.
b.—JPEG uses an algorithm to approximate the original image with less actual data. The accuracy of the approximation, or ratio of compression, determines how much detail is traded for the reduction in file size.
b.—The colors in the Web 216, or Websafe, palette will appear reasonably similar on almost any computer system. These colors should be the starting point when considering colors to be used on the Web and are intended to help foster color accuracy for creative and commercial images and artwork.