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author | William Joye <wjoye@cfa.harvard.edu> | 2016-10-27 20:28:26 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2016-10-27 20:28:26 (GMT) |
commit | b184baa1234c2143e488d1796ae98afab118b891 (patch) | |
tree | 686b0a47b272296205c7fa2bc789f62a03d20df6 /tkimg/doc/img-jpeg.man | |
parent | f7560d0a451a793441216d76eb4d9475aab61740 (diff) | |
parent | 5aad878400425d3af44433a47c13824385689e1d (diff) | |
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Merge commit '5aad878400425d3af44433a47c13824385689e1d' as 'tkimg'
Diffstat (limited to 'tkimg/doc/img-jpeg.man')
-rw-r--r-- | tkimg/doc/img-jpeg.man | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/tkimg/doc/img-jpeg.man b/tkimg/doc/img-jpeg.man new file mode 100644 index 0000000..e529151 --- /dev/null +++ b/tkimg/doc/img-jpeg.man @@ -0,0 +1,75 @@ +[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] |