184 lines
6.7 KiB
Text
184 lines
6.7 KiB
Text
oxipng 9.0.0
|
|
Losslessly improve compression of PNG files
|
|
|
|
Usage: oxipng [OPTIONS] <files>...
|
|
|
|
Arguments:
|
|
<files>...
|
|
File(s) to compress (use '-' for stdin)
|
|
|
|
Options:
|
|
-o, --opt <level>
|
|
Set the optimization level preset. The default level 2 is quite fast
|
|
and provides good compression. Lower levels are faster, higher levels
|
|
provide better compression, though with increasingly diminishing
|
|
returns.
|
|
|
|
0 => --zc 5 --fast (1 trial, determined heuristically)
|
|
1 => --zc 10 --fast (1 trial, determined heuristically)
|
|
2 => --zc 11 -f 0,1,6,7 --fast (4 fast trials, 1 main trial)
|
|
3 => --zc 11 -f 0,7,8,9 (4 trials)
|
|
4 => --zc 12 -f 0,7,8,9 (4 trials)
|
|
5 => --zc 12 -f 0,1,2,5,6,7,8,9 (8 trials)
|
|
6 => --zc 12 -f 0-9 (10 trials)
|
|
max => (stable alias for the max level)
|
|
|
|
Manually specifying a compression option (zc, f, etc.) will override
|
|
the optimization preset, regardless of the order you write the
|
|
arguments.
|
|
|
|
[default: 2]
|
|
|
|
-r, --recursive
|
|
When directories are given as input, traverse the directory trees and
|
|
optimize all PNG files found (files with “.png” or “.apng” extension).
|
|
|
|
--dir <directory>
|
|
Write output file(s) to <directory>. If the directory does not exist,
|
|
it will be created. Note that this will not preserve the directory
|
|
structure of the input files when used with '--recursive'.
|
|
|
|
--out <file>
|
|
Write output file to <file>
|
|
|
|
--stdout
|
|
Write output to stdout
|
|
|
|
-p, --preserve
|
|
Preserve file permissions and timestamps if possible.
|
|
|
|
Timestamps can only be preserved if oxipng was compiled with the
|
|
`filetime` feature.
|
|
|
|
-P, --pretend
|
|
Do not write any files, only show compression results
|
|
|
|
-s
|
|
Strip safely-removable chunks, same as '--strip safe'
|
|
|
|
--strip <mode>
|
|
Strip metadata chunks, where <mode> is one of:
|
|
|
|
safe => Strip all non-critical chunks, except for the following:
|
|
cICP, iCCP, sRGB, pHYs, acTL, fcTL, fdAT
|
|
all => Strip all non-critical chunks
|
|
<list> => Strip chunks in the comma-separated list, e.g. 'bKGD,cHRM'
|
|
|
|
CAUTION: 'all' will convert APNGs to standard PNGs.
|
|
|
|
--keep <list>
|
|
Strip all metadata except in the comma-separated list
|
|
|
|
-a, --alpha
|
|
Perform additional optimization on images with an alpha channel, by
|
|
altering the color values of fully transparent pixels. This is
|
|
generally recommended for better compression, but take care as this is
|
|
technically a lossy transformation and may be unsuitable for some
|
|
applications.
|
|
|
|
-i, --interlace <type>
|
|
Set the PNG interlacing type, where <type> is one of:
|
|
|
|
0 => Remove interlacing from all images that are processed
|
|
1 => Apply Adam7 interlacing on all images that are processed
|
|
keep => Keep the existing interlacing type of each image
|
|
|
|
Note that interlacing can add 25-50% to the size of an optimized
|
|
image. Only use it if you believe the benefits outweigh the costs for
|
|
your use case.
|
|
|
|
[default: 0]
|
|
|
|
--scale16
|
|
Forcibly reduce 16-bit images to 8-bit. Reduction is performed by
|
|
scaling the values, such that e.g. 0x00FF is reduced to 0x01 rather
|
|
than 0x00.
|
|
|
|
-v, --verbose...
|
|
Run in verbose mode (use twice to increase verbosity)
|
|
|
|
-q, --quiet
|
|
Run in quiet mode
|
|
|
|
-f, --filters <list>
|
|
Peform compression trials with each of the given filter types. You can
|
|
specify a comma-separated list, or a range of values. E.g. '-f 0-3' is
|
|
the same as '-f 0,1,2,3'.
|
|
|
|
PNG delta filters (apply the same filter to every line)
|
|
0 => None (recommended to always include this filter)
|
|
1 => Sub
|
|
2 => Up
|
|
3 => Average
|
|
4 => Paeth
|
|
Heuristic strategies (try to find the best delta filter for each line)
|
|
5 => MinSum Minimum sum of absolute differences
|
|
6 => Entropy Highest Shannon entropy
|
|
7 => Bigrams Lowest count of distinct bigrams
|
|
8 => BigEnt Highest Shannon entropy of bigrams
|
|
9 => Brute Smallest compressed size (slow)
|
|
|
|
The default value depends on the optimization level preset.
|
|
|
|
--fast
|
|
Perform a fast compression evaluation of each enabled filter, followed
|
|
by a single main compression trial of the best result. Recommended
|
|
if you have more filters enabled than CPU cores.
|
|
|
|
--zc <level>
|
|
zlib compression level (1-12)
|
|
|
|
--nb
|
|
No bit depth reduction
|
|
|
|
--nc
|
|
No color type reduction
|
|
|
|
--np
|
|
No palette reduction
|
|
|
|
--ng
|
|
No grayscale reduction
|
|
|
|
--nx
|
|
No reductions or deinterlacing
|
|
|
|
--nz
|
|
No recompression of IDAT unless reductions occur. Recompression of
|
|
other compressed chunks (such as iCCP) will also be disabled. Note
|
|
that the combination of '--nx' and '--nz' will fully disable all
|
|
optimization.
|
|
|
|
--fix
|
|
Do not perform checksum validation of PNG chunks. This may allow some
|
|
files with errors to be processed successfully.
|
|
|
|
--force
|
|
Write the output even if it is larger than the input
|
|
|
|
-Z, --zopfli
|
|
Use the slow but stronger Zopfli compressor. Recommended use is with
|
|
'-o max' and '--fast'.
|
|
|
|
This option is only available if oxipng was compiled with the `zopfli`
|
|
feature.
|
|
|
|
--timeout <secs>
|
|
Maximum amount of time, in seconds, to spend on optimizations. Oxipng
|
|
will check the timeout before each reduction or compression trial, and
|
|
will stop trying to optimize the file if the timeout is exceeded. Note
|
|
that this does not cut short any compression trials that are already
|
|
in progress, so it is currently of limited effectiveness for large
|
|
files or high compression levels.
|
|
|
|
-t, --threads <num>
|
|
Set number of threads to use [default: num CPU cores]
|
|
|
|
This option is only available if oxipng was compiled with the
|
|
`parallel` feature.
|
|
|
|
-h, --help
|
|
Print help (see a summary with '-h')
|
|
|
|
-V, --version
|
|
Print version
|