Technical data

98 Color and Input/Output Options
Compression
Compression schemes, which apply different algorithms to encode the
image information with fewer total bits and bytes, are used in many
formats. With some, like .BMP and .TIF, the Export Optimizer gives
you a choice of compression scheme. In general, use the default setting
unless you know for a fact that some other scheme is called for.
The .JPG format, widely used for photographs (and detailed in Chapter
6), is unusual in that you can set the level of quality desired using a
slider. As you might expect, the highest-quality setting uses least
compression, with no loss of image quality but the largest file size. The
lowest-quality setting applies maximum compression for smallest size,
but yields rather poor quality. With the aid of the Export Optimizer, you
can judge for yourself—but another factor to keep in mind is the
number of times you expect to be re-exporting a particular image. A
photograph may look fine the first time you export it at JPG level 6, but
after several such saves, you’ll really see the quality loss. As a rule,
keep images in the native .SPP format, or export them using only
lossless compression schemes, until it’s time for the final export.
File Formats
PhotoPlus can import and export most types of graphics file which
you’re likely to encounter. In order to use PhotoPlus images in other
programs, you will have to export them into one of the widely used
formats.
For pictures and animations intended for use on the World Wide Web,
the two prevalent formats are .GIF (for both) and .JPG (just for photos).
A newer format, .PNG, has some advantages but isn’t yet as widely
supported. See Chapter 6 for details on the features and options of each
format.
For print use, we recommend that you use .TIF or .BMP as most other
programs allow you to import files in that format.
If you’re exporting an image so that it can be used in four-color process
printing, then it is essential that you enable the CMYK option in the
Export Optimizer. The other export formats use the RGB color model
(see the section on “Color modes” earlier in this chapter), which is not
suitable for use in process printing.