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[comment {-*- tcl -*- doctools}]
[vset FORMATNAME jpeg]
[vset FORMATFULLNAME {Joint Picture Expert Group format}]
[include format-header.inc]
This handler provides new additional configuration options. See
section [sectref {JPEG OPTIONS}] for more detailed explanations.
[include format-middle.inc]
In addition the value for the option is treated as list and may
contain any of the special options listed in section
[sectref {JPEG OPTIONS}].
[list_end]
[section {JPEG OPTIONS}]
The handler provides six options, two effective when reading from a
JPEG image, and five influencing the writing of such. One option is
usable for both reading an writing.
[list_begin definitions]
[lst_item [option -fast]]
This option is for reading from JPEG data. It usage activates a
processing mode which is fast, but also provides only low-quality
information.
[lst_item [option -grayscale]]
This option can be used for both reading and writing of JPEG
data. Usage of this option forces incoming images to grayscale, and
written images will be monochrome.
[lst_item "[option -quality] [arg n]"]
This option is for writing JPEG data. It specifies the compression
level as a quality percentage. The higher the quality, the less the
compression. The nominal range for [arg n] is
[const 0]...[const 100]. Useful values are in the range
[const 5]...[const 95]. The default value is [const 75].
[lst_item "[option -smooth] [arg n]"]
This option is for writing JPEG data. When used the writer will smooth
the image before performing the compression. Values in the
[const 10]...[const 30] are usually enough. The default is [const 0],
i.e no smoothing.
[lst_item [option -optimize]]
This option is for writing JPEG data. It usage causes the writer to
optimize the huffman table used to encode the jpeg coefficients.
[lst_item [option -progressive]]
This option is for writing JPEG data. It usage causes the creation of
a [term progressive] JPEG file.
[include format-footer.inc]
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