Adobe PHOTOSHOP ELEMENTS Manual page 239

3 To create an enhanced JPEG with a slightly
smaller file size, select Optimized. The Optimized
JPEG format is recommended for maximum file
compression; however, some older browsers do
not support this feature.
4 Select Progressive to create an image that
displays progressively in a Web browser. The image
will display as a series of overlays, enabling viewers
to see a low-resolution version of the image before
it downloads completely.
Progressive JPEGs require more RAM for viewing,
and are not supported by some browsers.
To preserve the ICC profile of the image with
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the file, select ICC Profile.
ICC profiles are used by some browsers for color
correction. The ICC profile preserved depends on
your current color setting. (See "Using color
management" on page 65.)
6 If the original image contains transparency,
select a Matte color that matches the background
of your Web page. (See "Making transparent and
matted images" on page 233.)
Setting optimization options for GIF and
PNG-8 formats
GIF is the standard format for compressing images
with flat color and crisp detail, such as line art,
logos, or illustrations with type. (See "About GIF
format" on page 228.) Like the GIF format, PNG-8
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efficiently compresses solid areas of color while
preserving sharp detail; however, not all Web
browsers can display PNG-8 files. (See "About
PNG-8 format" on page 229.)
A
B
C
Optimization options for GIF format:
A. Optimization format B. Color reduction
algorithm C. Dither algorithm
GIF format and PNG-8 format can use up to 256
colors to describe an image. The process of deter-
mining which colors to use is called indexing
(which is why images in GIF and PNG-8 formats
are sometimes called indexed color images). To
convert an image to indexed color, Photoshop
Elements builds a color lookup table, which stores
and indexes the colors in the image. If a color in
the original image does not appear in the color
lookup table, the program chooses the closest one
or simulates the color using available colors.
To optimize an image in GIF or PNG-8 format:
Choose GIF or PNG-8 for the optimization
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format.
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User Guide