Web export formats in Fireworks

GIF, JPEG, and PNG are graphic file formats that are common in web development because they are highly compressible, making for faster transfer across the Internet. However, a graphic’s visual integrity can vary from one format to another, depending upon each format’s method of compression. Therefore, base your choice of file format upon the design and use of your graphic.

GIF

Graphics Interchange Format, or GIF, is the most popular web graphic format. Although it can contain only 256 colors, GIF offers good, lossless image compression. Also, GIFs can contain a transparent area and multiple frames for animation.

Compression

• Lossless compression means that no image quality is lost when an image is compressed. A GIF compresses by scanning horizontally across a row of pixels, finding solid areas of color, and then abbreviating identical areas of pixels in the file. Therefore, images with repetitive areas of solid color compress best when saved as GIFs. A GIF is usually ideal for cartoon-like graphics, logos, graphics with transparent areas, or animations. Note: Dithering or anti-aliasing GIF images produces larger files.

JPEG

JPEG is an alternative to GIF developed by the Joint Photographic Experts Group specifically for photographic images. JPEG supports millions of colors (24-bit).

Compression

• JPEG is a lossy format, which means that some image data is discarded when it is compressed, reducing the quality of the final file. However, image data can often be discarded with little or no noticeable difference in quality. When exporting a JPEG, use the Quality pop-up slider in the Export Preview to determine how much quality is lost when compressing the file. Use a high percentage setting to maintain image quality but compress less, producing larger files. Use a low percentage setting to yield a small file, but produce a lower-quality image.
  Use the Export Preview to test and compare the appearance and estimated file size with different Quality settings for an exported JPEG.
  Check either Optimized or Progressive to export the JPEG using optimized compression tables that can reduce file size.

Smoothing

Use smoothing to help lower the file size of JPEGs. Smoothing blurs hard edges, which do not compress well in JPEGs. To use smoothing, select a level from the Smoothing pop-up in the Export Preview. Higher numbers produce more blurring in the exported JPEG, typically creating smaller files.
Sharpening color edges
Check Sharpen Color Edges to help preserve fine edges between two colors. Use Sharpen Color Edges when exporting JPEGs with text or hard color transitions to preserve the sharpness of these areas
Progressive
Check Progressive in the Export Preview to export a progressive JPEG. Progressive JPEGs, like interlaced GIFs, display at low resolution and then increase in quality as they continue to download.
The JPEG format is best for scanned photographs, images using textures, images with gradient color transitions, or any images that require more than 256 colors.
Note: Many image editing applications cannot open progressive JPEGs.

PNG

The Portable Network Graphic, or PNG, is the most versatile of the web graphic formats. However, not all web browsers can take full advantage of PNG characteristics. A PNG supports up to 32-bit color, can contain transparency or an alpha channel, and can be progressive.