MACROMEDIA FIREWORKS MX 2004-USING FIREWORKS Use Manual page 244

Selectively compressing areas of a JPEG
Selective JPEG compression lets you compress different areas of a JPEG at different levels. Areas
of particular interest in an image can be compressed at a higher quality level. Areas of lesser
significance, such as backgrounds, can be compressed at a lower quality level, reducing the overall
size of the image while retaining the quality of the more important areas.
The selected area in this image is being compressed at a quality level of 90, while the unselected area is
being compressed at a quality level of 50.
To compress selected areas of a JPEG:
In Original view, select an area of the graphic for compression using one of the Marquee tools.
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Choose Modify > Selective JPEG > Save Selection as JPEG Mask.
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Choose JPEG from the Export File Format pop-up menu in the Optimize panel, if it's not
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already selected.
Click the Edit Selective Quality Options button in the Optimize panel.
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The Selective JPEG Settings dialog box opens.
Choose Enable Selective Quality and enter a value in the text box.
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Entering a low value compresses the Selective JPEG area more than the rest of the image.
Entering a high value compresses the Selective JPEG area less than the rest of the image.
Change the Overlay Color for the Selective JPEG area if desired. This does not affect
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the output.
Select Preserve Text Quality. All text items will automatically be exported at a higher level,
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regardless of the Selective Quality value.
Select Preserve Button Quality. All button symbols will automatically be exported at a
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higher level.
Click OK.
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To modify the selective JPEG compression area:
Choose Modify > Selective JPEG > Restore JPEG Mask as Selection.
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The selection is highlighted.
Use the Marquee tool or another selection tool to make changes to the size of the area.
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Choose Modify > Selective JPEG > Save Selection as JPEG Mask.
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Change selective quality settings in the Optimize panel if desired.
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Note: To undo a selection, choose Modify > Selective JPEG > Remove JPEG Mask.
244 Chapter 12: Optimizing and Exporting