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man/cwebp.1, cosmetics: escape '-'s

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+ consistently make references to switches bold
+ add the default for -pass

Change-Id: I84abd9c0c878f8804c0f5dec806ca654e00b6661
This commit is contained in:
James Zern 2015-11-03 17:59:45 -08:00
parent 96f5b4237d
commit 024324273e
1 changed files with 30 additions and 30 deletions
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man/cwebp.1
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@ -1,5 +1,5 @@
.\" Hey, EMACS: -*- nroff -*-
.TH CWEBP 1 "November 02, 2015"
.TH CWEBP 1 "November 03, 2015"
.SH NAME
cwebp \- compress an image file to a WebP file
.SH SYNOPSIS
@ -23,7 +23,7 @@ Using "\-" as output name will direct output to 'stdout'.
.TP
.BI \-\- " string
Explicitly specify the input file. This option is useful if the input
file starts with an '\-' for instance. This option must appear \fBlast\fP.
file starts with a '\-' for instance. This option must appear \fBlast\fP.
Any other options afterward will be ignored.
.TP
.B \-h, \-help
@ -39,7 +39,7 @@ Print the version number (as major.minor.revision) and exit.
Encode the image without any loss.
.TP
.BI \-near_lossless " int
Use near-lossless image preprocessing. This option adjusts pixel values
Use near\-lossless image preprocessing. This option adjusts pixel values
to help compressibility, but has minimal impact on the visual quality.
It triggers lossless compression mode automatically.
Range is 0 (maximum preprocessing) to 100 (no preprocessing, the default).
@ -51,17 +51,17 @@ is 75.
In case of lossy compression (default), a small factor produces a smaller file
with lower quality. Best quality is achieved by using a value of 100.
.br
In case of lossless compression (specified by the \-lossless option), a small
factor enables faster compression speed, but produces a larger file. Maximum
compression is achieved by using a value of 100.
In case of lossless compression (specified by the \fB\-lossless\fP option), a
small factor enables faster compression speed, but produces a larger file.
Maximum compression is achieved by using a value of 100.
.TP
.BI \-z " int
Switch on \fBlossless\fP compression mode with the specified level between 0
and 9, with level 0 being the fastest, 9 being the slowest. Fast mode
produces larger file size than slower ones. A good default is \-z 6.
produces larger file size than slower ones. A good default is \fB\-z 6\fP.
This option is actually a shortcut for some predefined settings for quality
and method. If options \-q or \-m are subsequently used, they will invalidate
the effect of this \-z option.
and method. If options \fB\-q\fP or \fB\-m\fP are subsequently used, they will
invalidate the effect of this option.
.TP
.BI \-alpha_q " int
Specify the compression factor for alpha compression between 0 and 100.
@ -69,7 +69,7 @@ Lossless compression of alpha is achieved using a value of 100, while the lower
values result in a lossy compression. The default is 100.
.TP
.BI \-preset " string
Specify a set of pre-defined parameters to suit a particular type of
Specify a set of pre\-defined parameters to suit a particular type of
source material. Possible values are: \fBdefault\fP, \fBphoto\fP,
\fBpicture\fP, \fBdrawing\fP, \fBicon\fP, \fBtext\fP. Since
\fB\-preset\fP overwrites the other parameters' values (except the
@ -88,15 +88,15 @@ larger file size and lower compression quality.
.BI \-resize " width height
Resize the source to a rectangle with size \fBwidth\fP x \fBheight\fP.
If either (but not both) of the \fBwidth\fP or \fBheight\fP parameters is 0,
the value will be calculated preserving the aspect-ratio.
the value will be calculated preserving the aspect\-ratio.
.TP
.BI \-crop " x_position y_position width height
Crop the source to a rectangle with top-left corner at coordinates
Crop the source to a rectangle with top\-left corner at coordinates
(\fBx_position\fP, \fBy_position\fP) and size \fBwidth\fP x \fBheight\fP.
This cropping area must be fully contained within the source rectangle.
.TP
.B \-mt
Use multi-threading for encoding, if possible. This option is only effective
Use multi\-threading for encoding, if possible. This option is only effective
when using lossy compression on a source with a transparency channel.
.TP
.B \-low_memory
@ -125,11 +125,11 @@ close as possible to this target.
.TP
.BI \-pass " int
Set a maximum number of passes to use during the dichotomy used by
options \fB\-size\fP or \fB\-psnr\fP. Maximum value is 10.
options \fB\-size\fP or \fB\-psnr\fP. Maximum value is 10, default is 1.
.TP
.B \-af
Turns auto-filter on. This algorithm will spend additional time optimizing
the filtering strength to reach a well-balanced quality.
Turns auto\-filter on. This algorithm will spend additional time optimizing
the filtering strength to reach a well\-balanced quality.
.TP
.B \-jpeg_like
Change the internal parameter mapping to better match the expected size
@ -162,7 +162,7 @@ Disable strong filtering (if filtering is being used thanks to the
.TP
.BI \-sns " int
Specify the amplitude of the spatial noise shaping. Spatial noise shaping
(or \fBsns\fP for short) refers to a general collection of built-in algorithms
(or \fBsns\fP for short) refers to a general collection of built\-in algorithms
used to decide which area of the picture should use relatively less bits,
and where else to better transfer these bits. The possible range goes from
0 (algorithm is off) to 100 (the maximal effect). The default value is 80.
@ -176,21 +176,21 @@ is used.
.BI \-partition_limit " int
Degrade quality by limiting the number of bits used by some macroblocks.
Range is 0 (no degradation, the default) to 100 (full degradation).
Useful values are usually around 30-70 for moderately large images.
In the VP8 format, the so-called control partition has a limit of 512k and
Useful values are usually around 30\-70 for moderately large images.
In the VP8 format, the so\-called control partition has a limit of 512k and
is used to store the following information: whether the macroblock is skipped,
which segment it belongs to, whether it is coded as intra 4x4 or intra 16x16
mode, and finally the prediction modes to use for each of the sub-blocks.
mode, and finally the prediction modes to use for each of the sub\-blocks.
For a very large image, 512k only leaves room to few bits per 16x16 macroblock.
The absolute minimum is 4 bits per macroblock. Skip, segment, and mode
information can use up almost all these 4 bits (although the case is unlikely),
which is problematic for very large images. The partition_limit factor controls
how frequently the most bit-costly mode (intra 4x4) will be used. This is
how frequently the most bit\-costly mode (intra 4x4) will be used. This is
useful in case the 512k limit is reached and the following message is displayed:
\fIError code: 6 (PARTITION0_OVERFLOW: Partition #0 is too big to fit 512k)\fP.
If using \fB-partition_limit\fP is not enough to meet the 512k constraint, one
If using \fB\-partition_limit\fP is not enough to meet the 512k constraint, one
should use less segments in order to save more header bits per macroblock.
See the \fB-segments\fP option.
See the \fB\-segments\fP option.
.SS LOGGING OPTIONS
These options control the level of output:
@ -199,7 +199,7 @@ These options control the level of output:
Print extra information (encoding time in particular).
.TP
.B \-print_psnr
Compute and report average PSNR (Peak-Signal-To-Noise ratio).
Compute and report average PSNR (Peak\-Signal\-To\-Noise ratio).
.TP
.B \-print_ssim
Compute and report average SSIM (structural similarity
@ -219,7 +219,7 @@ Do not print anything.
Only print brief information (output file size and PSNR) for testing purpose.
.TP
.BI \-map " int
Output additional ASCII-map of encoding information. Possible map values
Output additional ASCII\-map of encoding information. Possible map values
range from 1 to 6. This is only meant to help debugging.
.SS ADDITIONAL OPTIONS
@ -227,12 +227,12 @@ More advanced options are:
.TP
.BI \-s " width height
Specify that the input file actually consists of raw Y'CbCr samples following
the ITU-R BT.601 recommendation, in 4:2:0 linear format.
the ITU\-R BT.601 recommendation, in 4:2:0 linear format.
The luma plane has size \fBwidth\fP x \fBheight\fP.
.TP
.BI \-pre " int
Specify some pre-processing steps. Using a value of '2' will trigger
quality-dependent pseudo-random dithering during RGBA->YUVA conversion
Specify some preprocessing steps. Using a value of '2' will trigger
quality\-dependent pseudo\-random dithering during RGBA\->YUVA conversion
(lossy compression only).
.TP
.BI \-alpha_filter " string
@ -241,7 +241,7 @@ Specify the predictive filtering method for the alpha plane. One of 'none',
\&'fast'. Internally, alpha filtering is performed using four possible
predictions (none, horizontal, vertical, gradient). The 'best' mode will try
each mode in turn and pick the one which gives the smaller size. The 'fast'
mode will just try to form an a-priori guess without testing all modes.
mode will just try to form an a priori guess without testing all modes.
.TP
.BI \-alpha_method " int
Specify the algorithm used for alpha compression: 0 or 1. Algorithm 0 denotes
@ -279,7 +279,7 @@ Please report all bugs to our issue tracker:
https://bugs.chromium.org/p/webp
.br
Patches welcome! See this page to get started:
http://www.webmproject.org/code/contribute/submitting-patches/
http://www.webmproject.org/code/contribute/submitting\-patches/
.SH EXAMPLES
cwebp \-q 50 -lossless picture.png \-o picture_lossless.webp