Jpeg - MACROMEDIA FIREWORKS 2-USING FIREWORKS Use Manual

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.
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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.