Copyright (C) 1998-2002,2006 Glenn Randers-Pehrson (glennrp@users.sf.net)
Copyright (C) 2005 Greg Roelofs
DISCLAIMER: The pngcrush computer program is supplied "AS IS".
The Author disclaims all warranties, expressed or implied, including,
without limitation, the warranties of merchantability and of fitness
for any purpose. The Author assumes no liability for direct, indirect,
incidental, special, exemplary, or consequential damages, which may
result from the use of the computer program, even if advised of the
possibility of such damage. There is no warranty against interference
with your enjoyment of the computer program or against infringement.
There is no warranty that my efforts or the computer program will
fulfill any of your particular purposes or needs. This computer
program is provided with all faults, and the entire risk of satisfactory
quality, performance, accuracy, and effort is with the user.
LICENSE: Permission is hereby irrevocably granted to everyone to use,
copy, modify, and distribute this computer program, or portions hereof,
purpose, without payment of any fee, subject to the following
restrictions:
1. The origin of this binary or source code must not be misrepresented.
2. Altered versions must be plainly marked as such and must not be
misrepresented as being the original binary or source.
3. The Copyright notice, disclaimer, and license may not be removed
or altered from any source, binary, or altered source distribution.
usage: pngcrush [options] infile.png outfile.png
pngcrush -e ext [other options] files.png ...
pngcrush -d dir [other options] files.png ...
options:
-already already_crushed_size [e.g., 8192]
-bit_depth depth (bit_depth to use in output file)
-brute (use brute-force: try 126 different methods [11-136])
-c color_type of output file [0, 2, 4, or 6]
-d directory_name (where output files will go)
-double_gamma (used for fixing gamma in PhotoShop 5.0/5.02 files)
-e extension (used for creating output filename)
-f user_filter [0-5]
-fix (fix otherwise fatal conditions such as bad CRCs)
-force (write a new output file even if larger than input)
-g gamma (float or fixed*100000, e.g., 0.45455 or 45455)
-huffman (use only zlib strategy 2, Huffman-only)
-iccp length "Profile Name" iccp_file
-itxt b[efore_IDAT]|a[fter_IDAT] "keyword"
-l zlib_compression_level [0-9]
-loco ("loco crush" truecolor PNGs)
-m method [0 through 200]
-max maximum_IDAT_size [default 8192]
-nofilecheck (do not check for infile.png == outfile.png)
-n (no save; does not do compression or write output PNG)
-plte_len n (truncate PLTE)
-q (quiet)
-reduce (do lossless color-type or bit-depth reduction)
-rem chunkname (or "alla" or "allb")
-replace_gamma gamma (float or fixed*100000) even if gAMA is present.
-res dpi
-rle (use only zlib strategy 3, RLE-only)
-save (keep all copy-unsafe chunks)
-srgb [0, 1, 2, or 3]
-text b[efore_IDAT]|a[fter_IDAT] "keyword" "text"
-trns_array n trns[0] trns[1] .. trns[n-1]
-trns index red green blue gray
-v (display more detailed information)
-version (display the pngcrush version)
-w compression_window_size [32, 16, 8, 4, 2, 1, 512]
-z zlib_strategy [0, 1, 2, or 3]
-zmem zlib_compression_mem_level [1-9, default 9]
-zitxt b[efore_IDAT]|a[fter_IDAT] "keyword"
-ztxt b[efore_IDAT]|a[fter_IDAT] "keyword" "text"
-h (help and legal notices)
-p (pause)
options (Note: any option can be spelled out for clarity, e.g.,
"pngcrush -dir New -method 7 -remove bkgd *.png"
is the same as "pngcrush -d New -m 7 -rem bkgd *.png"):
-already already_crushed_size [e.g., 8192]
If file has an IDAT greater than this size, it
will be considered to be already crushed and will
not be processed, unless you are making other changes
or the "-force" option is present.
-bit_depth depth (bit_depth to use in output file)
Default output depth is same as input depth.
-brute (use brute-force: try 126 different methods [11-136])
Very time-consuming and generally not worthwhile.
You can restrict this option to certain filter types,
compression levels, or strategies by following it
with "-f filter", "-l level", or "-z strategy".
-c color_type of output file [0, 2, 4, or 6]
Color type for the output file. Future versions
will also allow color_type 3, if there are 256 or
fewer colors present in the input file. Color types
4 and 6 are padded with an opaque alpha channel if
the input file does not have alpha information.
You can use 0 or 4 to convert color to grayscale.
Use 0 or 2 to delete an unwanted alpha channel.
Default is to use same color type as the input file.
-d directory_name (where output files will go)
If a directory name is given, then the output
files are placed in it, with the same filenames as
those of the original files. For example,
you would type 'pngcrush -directory CRUSHED *.png'
to get *.png => CRUSHED/*.png
-double_gamma (used for fixing gamma in PhotoShop 5.0/5.02 files)
It has been claimed that the PS5 bug is actually
more complex than that, in some unspecified way.
-e extension (used for creating output filename)
e.g., -ext .new means *.png => *.new
and -e _C.png means *.png => *_C.png
-f user_filter [0-5]
filter to use with the method specified in the
preceding '-m method' or '-brute_force' argument.
0: none; 1-4: use specified filter; 5: adaptive.
-fix (fix otherwise fatal conditions such as bad CRCs)
-force (write a new output file even if larger than input)
Otherwise the input file will be copied to output
if it is smaller than any generated file and no chunk
additions, removals, or changes were requested.
-g gamma (float or fixed*100000, e.g., 0.45455 or 45455)
Value to insert in gAMA chunk, only if the input
file has no gAMA chunk. To replace an existing
gAMA chunk, use the '-replace_gamma' option.
-huffman (use only zlib strategy 2, Huffman-only)
Fast, but almost never very effective except for
certain rare image types.
-iccp length "Profile Name" iccp_file
file with ICC profile to insert in an iCCP chunk.
-itxt b[efore_IDAT]|a[fter_IDAT] "keyword"
"language_code" "translated_keyword" "text"
Uncompressed iTXt chunk to insert (see -text).
-l zlib_compression_level [0-9]
zlib compression level to use with method specified
with the preceding '-m method' or '-brute_force'
argument.
-loco ("loco crush" truecolor PNGs)
Make the file more compressible by performing a
lossless, reversible, color transformation.
The resulting file is a MNG, not a PNG, and should
be given the ".mng" file extension. The
"loco" option has no effect on grayscale or
indexed-color PNG files.
-m method [0 through 200]
pngcrush method to try (0 means try all of 1-10).
Can be repeated as in '-m 1 -m 4 -m 7'.
This can be useful if pngcrush runs out of memory
when it tries methods 2, 3, 5, 6, 8, 9, or 10 which
use filtering and are memory-intensive. Methods
1, 4, and 7 use no filtering; methods 11 and up use
specified filter, compression level, and strategy.
-max maximum_IDAT_size [default 8192]
-nofilecheck (do not check for infile.png == outfile.png)
To avoid false hits from MSVC-compiled code. Note
that if you use this option, you are responsible for
ensuring that the input file is not the output file.
-n (no save; does not do compression or write output PNG)
Useful in conjunction with -v option to get info.
-plte_len n (truncate PLTE)
Truncates the PLTE. Be sure not to truncate it to
less than the greatest index present in IDAT.
-q (quiet)
-reduce (do lossless color-type or bit-depth reduction)
(if possible)
-rem chunkname (or "alla" or "allb")
Name of an ancillary chunk or optional PLTE to be
removed. Be careful with this. Please don't use
this feature to remove transparency, gamma, copyright,
or other valuable information. To remove several
different chunks, repeat: -rem tEXt -rem pHYs.
Known chunks (those in the PNG 1.1 spec or extensions
document) can be named with all lower-case letters,
so "-rem bkgd" is equivalent to "-rem bKGD". But
note: "-rem text" removes all forms of text chunks;
Exact case is required to remove unknown chunks.
To do surgery with a chain-saw, "-rem alla" removes
all known ancillary chunks except for tRNS, and
"-rem allb" removes all but tRNS and gAMA.
-replace_gamma gamma (float or fixed*100000) even if gAMA is present.
-res dpi
Write a pHYs chunk with the given resolution.
-rle (use only zlib strategy 3, RLE-only)
A relatively fast subset of the "-brute" methods,
generally more effective than "-huffman" on PNG images
(and quite effective on black-and-white images),
but not necessarily worth the bother otherwise.
-save (keep all copy-unsafe chunks)
Save otherwise unknown ancillary chunks that would
be considered copy-unsafe. This option makes
chunks 'known' to pngcrush, so they can be copied.
-srgb [0, 1, 2, or 3]
Value of 'rendering intent' for sRGB chunk.
-text b[efore_IDAT]|a[fter_IDAT] "keyword" "text"
tEXt chunk to insert. keyword < 80 chars,
text < 2048 chars. For now, you can add no more than
ten tEXt, iTXt, or zTXt chunks per pngcrush run.
-trns_array n trns[0] trns[1] .. trns[n-1]
Insert a tRNS chunk, if no tRNS chunk found in file.
Values are for the tRNS array in indexed-color PNG.
-trns index red green blue gray
Insert a tRNS chunk, if no tRNS chunk found in file.
You must give all five parameters regardless of the
color type, scaled to the output bit depth.
-v (display more detailed information)
Repeat the option (use "-v -v") for even more.
-version (display the pngcrush version)
Look for the most recent version of pngcrush at
http://pmt.sf.net
-w compression_window_size [32, 16, 8, 4, 2, 1, 512]
Size of the sliding compression window, in kbytes
(or bytes, in case of 512). It's best to
use the default (32) unless you run out of memory.
The program will use a smaller window anyway when
the uncompressed file is smaller than 16k.
-z zlib_strategy [0, 1, 2, or 3]
zlib compression strategy to use with the preceding
'-m method' argument.
-zmem zlib_compression_mem_level [1-9, default 9]
-zitxt b[efore_IDAT]|a[fter_IDAT] "keyword"
"language_code" "translated_keyword" "text"
Compressed iTXt chunk to insert (see -text).
-ztxt b[efore_IDAT]|a[fter_IDAT] "keyword" "text"
zTXt chunk to insert (see -text).
-h (help and legal notices)
Display this information.
-p (pause)
Wait for [enter] key before continuing display.
e.g., type 'pngcrush -pause -help', if the help
screen scrolls out of sight.