Cluster/Cluster
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

feat(clusterApp):BringUp OpenGlES+DRM on RK3576

Browse Source
This commit is contained in:
zhimin.liu
2026-04-28 21:30:18 +08:00
parent f3f5d1b00b
commit d5b56baefc
213 changed files with 136403 additions and 678 deletions
Download Patch File Download Diff File Expand all files Collapse all files

387
packages/install/usr/share/man/man1/cjpeg.1 Normal file
View File

@@ -0,0 +1,387 @@
.TH CJPEG 1 "26 July 2015"
.SH NAME
cjpeg \- compress an image file to a JPEG file
.SH SYNOPSIS
.B cjpeg
[
.I options
]
[
.I filename
]
.LP
.SH DESCRIPTION
.LP
.B cjpeg
compresses the named image file, or the standard input if no file is
named, and produces a JPEG/JFIF file on the standard output.
The currently supported input file formats are: PPM (PBMPLUS color
format), PGM (PBMPLUS grayscale format), BMP, Targa, and RLE (Utah Raster
Toolkit format). (RLE is supported only if the URT library is available.)
.SH OPTIONS
All switch names may be abbreviated; for example,
.B \-grayscale
may be written
.B \-gray
or
.BR \-gr .
Most of the "basic" switches can be abbreviated to as little as one letter.
Upper and lower case are equivalent (thus
.B \-BMP
is the same as
.BR \-bmp ).
British spellings are also accepted (e.g.,
.BR \-greyscale ),
though for brevity these are not mentioned below.
.PP
The basic switches are:
.TP
.BI \-quality " N[,...]"
Scale quantization tables to adjust image quality. Quality is 0 (worst) to
100 (best); default is 75. (See below for more info.)
.TP
.B \-grayscale
Create monochrome JPEG file from color input. Be sure to use this switch when
compressing a grayscale BMP file, because
.B cjpeg
isn't bright enough to notice whether a BMP file uses only shades of gray.
By saying
.BR \-grayscale ,
you'll get a smaller JPEG file that takes less time to process.
.TP
.B \-rgb
Create RGB JPEG file.
Using this switch suppresses the conversion from RGB
colorspace input to the default YCbCr JPEG colorspace.
You can use this switch in combination with the
.BI \-block " N"
switch (see below) for lossless JPEG coding.
See also the
.B \-rgb1
switch below.
.TP
.B \-optimize
Perform optimization of entropy encoding parameters. Without this, default
encoding parameters are used.
.B \-optimize
usually makes the JPEG file a little smaller, but
.B cjpeg
runs somewhat slower and needs much more memory. Image quality and speed of
decompression are unaffected by
.BR \-optimize .
.TP
.B \-progressive
Create progressive JPEG file (see below).
.TP
.BI \-scale " M/N"
Scale the output image by a factor M/N. Currently supported scale factors are
M/N with all N from 1 to 16, where M is the destination DCT size, which is 8
by default (see
.BI \-block " N"
switch below).
.TP
.B \-targa
Input file is Targa format. Targa files that contain an "identification"
field will not be automatically recognized by
.BR cjpeg ;
for such files you must specify
.B \-targa
to make
.B cjpeg
treat the input as Targa format.
For most Targa files, you won't need this switch.
.PP
The
.B \-quality
switch lets you trade off compressed file size against quality of the
reconstructed image: the higher the quality setting, the larger the JPEG file,
and the closer the output image will be to the original input. Normally you
want to use the lowest quality setting (smallest file) that decompresses into
something visually indistinguishable from the original image. For this
purpose the quality setting should be between 50 and 95; the default of 75 is
often about right. If you see defects at
.B \-quality
75, then go up 5 or 10 counts at a time until you are happy with the output
image. (The optimal setting will vary from one image to another.)
.PP
.B \-quality
100 will generate a quantization table of all 1's, minimizing loss in the
quantization step (but there is still information loss in subsampling, as well
as roundoff error). This setting is mainly of interest for experimental
purposes. Quality values above about 95 are
.B not
recommended for normal use; the compressed file size goes up dramatically for
hardly any gain in output image quality.
.PP
In the other direction, quality values below 50 will produce very small files
of low image quality. Settings around 5 to 10 might be useful in preparing an
index of a large image library, for example. Try
.B \-quality
2 (or so) for some amusing Cubist effects. (Note: quality
values below about 25 generate 2-byte quantization tables, which are
considered optional in the JPEG standard.
.B cjpeg
emits a warning message when you give such a quality value, because some
other JPEG programs may be unable to decode the resulting file. Use
.B \-baseline
if you need to ensure compatibility at low quality values.)
.PP
The
.B \-quality
option has been extended in IJG version 7 for support of separate quality
settings for luminance and chrominance (or in general, for every provided
quantization table slot). This feature is useful for high-quality
applications which cannot accept the damage of color data by coarse
subsampling settings. You can now easily reduce the color data amount more
smoothly with finer control without separate subsampling. The resulting file
is fully compliant with standard JPEG decoders.
Note that the
.B \-quality
ratings refer to the quantization table slots, and that the last value is
replicated if there are more q-table slots than parameters. The default
q-table slots are 0 for luminance and 1 for chrominance with default tables as
given in the JPEG standard. This is compatible with the old behaviour in case
that only one parameter is given, which is then used for both luminance and
chrominance (slots 0 and 1). More or custom quantization tables can be set
with
.B \-qtables
and assigned to components with
.B \-qslots
parameter (see the "wizard" switches below).
.B Caution:
You must explicitly add
.BI \-sample " 1x1"
for efficient separate color
quality selection, since the default value used by library is 2x2!
.PP
The
.B \-progressive
switch creates a "progressive JPEG" file. In this type of JPEG file, the data
is stored in multiple scans of increasing quality. If the file is being
transmitted over a slow communications link, the decoder can use the first
scan to display a low-quality image very quickly, and can then improve the
display with each subsequent scan. The final image is exactly equivalent to a
standard JPEG file of the same quality setting, and the total file size is
about the same --- often a little smaller.
.PP
Switches for advanced users:
.TP
.B \-arithmetic
Use arithmetic coding.
.B Caution:
arithmetic coded JPEG is not yet widely implemented, so many decoders will
be unable to view an arithmetic coded JPEG file at all.
.TP
.BI \-block " N"
Set DCT block size. All N from 1 to 16 are possible.
Default is 8 (baseline format).
Larger values produce higher compression,
smaller values produce higher quality
(exact DCT stage possible with 1 or 2; with the default quality of 75 and
default Luminance qtable the DCT+Quantization stage is lossless for N=1).
.B Caution:
An implementation of the JPEG SmartScale extension is required for this
feature. SmartScale enabled JPEG is not yet widely implemented, so many
decoders will be unable to view a SmartScale extended JPEG file at all.
.TP
.B \-rgb1
Create RGB JPEG file with reversible color transform.
Works like the
.B \-rgb
switch (see above) and inserts a simple reversible color transform
into the processing which significantly improves the compression.
Use this switch in combination with the
.BI \-block " N"
switch (see above) for lossless JPEG coding.
.B Caution:
A decoder with inverse color transform support is required for
this feature. Reversible color transform support is not yet
widely implemented, so many decoders will be unable to view
a reversible color transformed JPEG file at all.
.TP
.B \-bgycc
Create big gamut YCC JPEG file.
In this type of encoding the color difference components are quantized
further by a factor of 2 compared to the normal Cb/Cr values, thus creating
space to allow larger color values with higher saturation than the normal
gamut limits to be encoded. In order to compensate for the loss of color
fidelity compared to a normal YCC encoded file, the color quantization
tables can be adjusted accordingly. For example,
.B cjpeg \-bgycc \-quality
80,90 will give similar results as
.B cjpeg \-quality
80.
.B Caution:
For correct decompression a decoder with big gamut YCC support (JFIF
version 2) is required. An old decoder may or may not display a big
gamut YCC encoded JPEG file, depending on JFIF version check and
corresponding warning/error configuration. In case of a granted
decompression the old decoder will display the image with half
saturated colors.
.TP
.B \-dct int
Use integer DCT method (default).
.TP
.B \-dct fast
Use fast integer DCT (less accurate).
.TP
.B \-dct float
Use floating-point DCT method.
The float method is very slightly more accurate than the int method, but is
much slower unless your machine has very fast floating-point hardware. Also
note that results of the floating-point method may vary slightly across
machines, while the integer methods should give the same results everywhere.
The fast integer method is much less accurate than the other two.
.TP
.B \-nosmooth
Don't use high-quality downsampling.
.TP
.BI \-restart " N"
Emit a JPEG restart marker every N MCU rows, or every N MCU blocks if "B" is
attached to the number.
.B \-restart 0
(the default) means no restart markers.
.TP
.BI \-smooth " N"
Smooth the input image to eliminate dithering noise. N, ranging from 1 to
100, indicates the strength of smoothing. 0 (the default) means no smoothing.
.TP
.BI \-maxmemory " N"
Set limit for amount of memory to use in processing large images. Value is
in thousands of bytes, or millions of bytes if "M" is attached to the
number. For example,
.B \-max 4m
selects 4000000 bytes. If more space is needed, temporary files will be used.
.TP
.BI \-outfile " name"
Send output image to the named file, not to standard output.
.TP
.B \-verbose
Enable debug printout. More
.BR \-v 's
give more output. Also, version information is printed at startup.
.TP
.B \-debug
Same as
.BR \-verbose .
.PP
The
.B \-restart
option inserts extra markers that allow a JPEG decoder to resynchronize after
a transmission error. Without restart markers, any damage to a compressed
file will usually ruin the image from the point of the error to the end of the
image; with restart markers, the damage is usually confined to the portion of
the image up to the next restart marker. Of course, the restart markers
occupy extra space. We recommend
.B \-restart 1
for images that will be transmitted across unreliable networks such as Usenet.
.PP
The
.B \-smooth
option filters the input to eliminate fine-scale noise. This is often useful
when converting dithered images to JPEG: a moderate smoothing factor of 10 to
50 gets rid of dithering patterns in the input file, resulting in a smaller
JPEG file and a better-looking image. Too large a smoothing factor will
visibly blur the image, however.
.PP
Switches for wizards:
.TP
.B \-baseline
Force baseline-compatible quantization tables to be generated. This clamps
quantization values to 8 bits even at low quality settings. (This switch is
poorly named, since it does not ensure that the output is actually baseline
JPEG. For example, you can use
.B \-baseline
and
.B \-progressive
together.)
.TP
.BI \-qtables " file"
Use the quantization tables given in the specified text file.
.TP
.BI \-qslots " N[,...]"
Select which quantization table to use for each color component.
.TP
.BI \-sample " HxV[,...]"
Set JPEG sampling factors for each color component.
.TP
.BI \-scans " file"
Use the scan script given in the specified text file.
.PP
The "wizard" switches are intended for experimentation with JPEG. If you
don't know what you are doing, \fBdon't use them\fR. These switches are
documented further in the file wizard.txt.
.SH EXAMPLES
.LP
This example compresses the PPM file foo.ppm with a quality factor of
60 and saves the output as foo.jpg:
.IP
.B cjpeg \-quality
.I 60 foo.ppm
.B >
.I foo.jpg
.SH HINTS
Color GIF files are not the ideal input for JPEG; JPEG is really intended for
compressing full-color (24-bit) images. In particular, don't try to convert
cartoons, line drawings, and other images that have only a few distinct
colors. GIF works great on these, JPEG does not. If you want to convert a
GIF to JPEG, you should experiment with
.BR cjpeg 's
.B \-quality
and
.B \-smooth
options to get a satisfactory conversion.
.B \-smooth 10
or so is often helpful.
.PP
Avoid running an image through a series of JPEG compression/decompression
cycles. Image quality loss will accumulate; after ten or so cycles the image
may be noticeably worse than it was after one cycle. It's best to use a
lossless format while manipulating an image, then convert to JPEG format when
you are ready to file the image away.
.PP
The
.B \-optimize
option to
.B cjpeg
is worth using when you are making a "final" version for posting or archiving.
It's also a win when you are using low quality settings to make very small
JPEG files; the percentage improvement is often a lot more than it is on
larger files. (At present,
.B \-optimize
mode is always selected when generating progressive JPEG files.)
.SH ENVIRONMENT
.TP
.B JPEGMEM
If this environment variable is set, its value is the default memory limit.
The value is specified as described for the
.B \-maxmemory
switch.
.B JPEGMEM
overrides the default value specified when the program was compiled, and
itself is overridden by an explicit
.BR \-maxmemory .
.SH SEE ALSO
.BR djpeg (1),
.BR jpegtran (1),
.BR rdjpgcom (1),
.BR wrjpgcom (1)
.br
.BR ppm (5),
.BR pgm (5)
.br
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
GIF input files are no longer supported, to avoid the Unisys LZW patent
(now expired).
(Conversion of GIF files to JPEG is usually a bad idea anyway.)
.PP
Not all variants of BMP and Targa file formats are supported.
.PP
The
.B \-targa
switch is not a bug, it's a feature. (It would be a bug if the Targa format
designers had not been clueless.)

257
packages/install/usr/share/man/man1/djpeg.1 Normal file
View File

@@ -0,0 +1,257 @@
.TH DJPEG 1 "26 July 2015"
.SH NAME
djpeg \- decompress a JPEG file to an image file
.SH SYNOPSIS
.B djpeg
[
.I options
]
[
.I filename
]
.LP
.SH DESCRIPTION
.LP
.B djpeg
decompresses the named JPEG file, or the standard input if no file is named,
and produces an image file on the standard output. PBMPLUS (PPM/PGM), BMP,
GIF, Targa, or RLE (Utah Raster Toolkit) output format can be selected.
(RLE is supported only if the URT library is available.)
.SH OPTIONS
All switch names may be abbreviated; for example,
.B \-grayscale
may be written
.B \-gray
or
.BR \-gr .
Most of the "basic" switches can be abbreviated to as little as one letter.
Upper and lower case are equivalent (thus
.B \-BMP
is the same as
.BR \-bmp ).
British spellings are also accepted (e.g.,
.BR \-greyscale ),
though for brevity these are not mentioned below.
.PP
The basic switches are:
.TP
.BI \-colors " N"
Reduce image to at most N colors. This reduces the number of colors used in
the output image, so that it can be displayed on a colormapped display or
stored in a colormapped file format. For example, if you have an 8-bit
display, you'd need to reduce to 256 or fewer colors.
.TP
.BI \-quantize " N"
Same as
.BR \-colors .
.B \-colors
is the recommended name,
.B \-quantize
is provided only for backwards compatibility.
.TP
.B \-fast
Select recommended processing options for fast, low quality output. (The
default options are chosen for highest quality output.) Currently, this is
equivalent to \fB\-dct fast \-nosmooth \-onepass \-dither ordered\fR.
.TP
.B \-grayscale
Force grayscale output even if JPEG file is color.
Useful for viewing on monochrome displays; also,
.B djpeg
runs noticeably faster in this mode.
.TP
.B \-rgb
Force RGB output even if JPEG file is grayscale.
This is provided to support applications that don't
want to cope with grayscale as a separate case.
.TP
.BI \-scale " M/N"
Scale the output image by a factor M/N. Currently supported scale factors are
M/N with all M from 1 to 16, where N is the source DCT size, which is 8 for
baseline JPEG. If the /N part is omitted, then M specifies the DCT scaled
size to be applied on the given input. For baseline JPEG this is equivalent
to M/8 scaling, since the source DCT size for baseline JPEG is 8.
Scaling is handy if the image is larger than your screen; also,
.B djpeg
runs much faster when scaling down the output.
.TP
.B \-bmp
Select BMP output format (Windows flavor). 8-bit colormapped format is
emitted if
.B \-colors
or
.B \-grayscale
is specified, or if the JPEG file is grayscale; otherwise, 24-bit full-color
format is emitted.
.TP
.B \-gif
Select GIF output format. Since GIF does not support more than 256 colors,
.B \-colors 256
is assumed (unless you specify a smaller number of colors).
.TP
.B \-os2
Select BMP output format (OS/2 1.x flavor). 8-bit colormapped format is
emitted if
.B \-colors
or
.B \-grayscale
is specified, or if the JPEG file is grayscale; otherwise, 24-bit full-color
format is emitted.
.TP
.B \-pnm
Select PBMPLUS (PPM/PGM) output format (this is the default format).
PGM is emitted if the JPEG file is grayscale or if
.B \-grayscale
is specified; otherwise PPM is emitted.
.TP
.B \-rle
Select RLE output format. (Requires URT library.)
.TP
.B \-targa
Select Targa output format. Grayscale format is emitted if the JPEG file is
grayscale or if
.B \-grayscale
is specified; otherwise, colormapped format is emitted if
.B \-colors
is specified; otherwise, 24-bit full-color format is emitted.
.PP
Switches for advanced users:
.TP
.B \-dct int
Use integer DCT method (default).
.TP
.B \-dct fast
Use fast integer DCT (less accurate).
.TP
.B \-dct float
Use floating-point DCT method.
The float method is very slightly more accurate than the int method, but is
much slower unless your machine has very fast floating-point hardware. Also
note that results of the floating-point method may vary slightly across
machines, while the integer methods should give the same results everywhere.
The fast integer method is much less accurate than the other two.
.TP
.B \-dither fs
Use Floyd-Steinberg dithering in color quantization.
.TP
.B \-dither ordered
Use ordered dithering in color quantization.
.TP
.B \-dither none
Do not use dithering in color quantization.
By default, Floyd-Steinberg dithering is applied when quantizing colors; this
is slow but usually produces the best results. Ordered dither is a compromise
between speed and quality; no dithering is fast but usually looks awful. Note
that these switches have no effect unless color quantization is being done.
Ordered dither is only available in
.B \-onepass
mode.
.TP
.BI \-map " file"
Quantize to the colors used in the specified image file. This is useful for
producing multiple files with identical color maps, or for forcing a
predefined set of colors to be used. The
.I file
must be a GIF or PPM file. This option overrides
.B \-colors
and
.BR \-onepass .
.TP
.B \-nosmooth
Don't use high-quality upsampling.
.TP
.B \-onepass
Use one-pass instead of two-pass color quantization. The one-pass method is
faster and needs less memory, but it produces a lower-quality image.
.B \-onepass
is ignored unless you also say
.B \-colors
.IR N .
Also, the one-pass method is always used for grayscale output (the two-pass
method is no improvement then).
.TP
.BI \-maxmemory " N"
Set limit for amount of memory to use in processing large images. Value is
in thousands of bytes, or millions of bytes if "M" is attached to the
number. For example,
.B \-max 4m
selects 4000000 bytes. If more space is needed, temporary files will be used.
.TP
.BI \-outfile " name"
Send output image to the named file, not to standard output.
.TP
.B \-verbose
Enable debug printout. More
.BR \-v 's
give more output. Also, version information is printed at startup.
.TP
.B \-debug
Same as
.BR \-verbose .
.SH EXAMPLES
.LP
This example decompresses the JPEG file foo.jpg, quantizes it to
256 colors, and saves the output in 8-bit BMP format in foo.bmp:
.IP
.B djpeg \-colors 256 \-bmp
.I foo.jpg
.B >
.I foo.bmp
.SH HINTS
To get a quick preview of an image, use the
.B \-grayscale
and/or
.B \-scale
switches.
.B \-grayscale \-scale 1/8
is the fastest case.
.PP
Several options are available that trade off image quality to gain speed.
.B \-fast
turns on the recommended settings.
.PP
.B \-dct fast
and/or
.B \-nosmooth
gain speed at a small sacrifice in quality.
When producing a color-quantized image,
.B \-onepass \-dither ordered
is fast but much lower quality than the default behavior.
.B \-dither none
may give acceptable results in two-pass mode, but is seldom tolerable in
one-pass mode.
.PP
If you are fortunate enough to have very fast floating point hardware,
\fB\-dct float\fR may be even faster than \fB\-dct fast\fR. But on most
machines \fB\-dct float\fR is slower than \fB\-dct int\fR; in this case it is
not worth using, because its theoretical accuracy advantage is too small to be
significant in practice.
.SH ENVIRONMENT
.TP
.B JPEGMEM
If this environment variable is set, its value is the default memory limit.
The value is specified as described for the
.B \-maxmemory
switch.
.B JPEGMEM
overrides the default value specified when the program was compiled, and
itself is overridden by an explicit
.BR \-maxmemory .
.SH SEE ALSO
.BR cjpeg (1),
.BR jpegtran (1),
.BR rdjpgcom (1),
.BR wrjpgcom (1)
.br
.BR ppm (5),
.BR pgm (5)
.br
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
To avoid the Unisys LZW patent (now expired),
.B djpeg
produces uncompressed GIF files. These are larger than they should be, but
are readable by standard GIF decoders.

306
packages/install/usr/share/man/man1/jpegtran.1 Normal file
View File

@@ -0,0 +1,306 @@
.TH JPEGTRAN 1 "30 September 2017"
.SH NAME
jpegtran \- lossless transformation of JPEG files
.SH SYNOPSIS
.B jpegtran
[
.I options
]
[
.I filename
]
.LP
.SH DESCRIPTION
.LP
.B jpegtran
performs various useful transformations of JPEG files.
It can translate the coded representation from one variant of JPEG to another,
for example from baseline JPEG to progressive JPEG or vice versa. It can also
perform some rearrangements of the image data, for example turning an image
from landscape to portrait format by rotation.
.PP
For EXIF files and JPEG files containing Exif data, you may prefer to use
.B exiftran
instead.
.PP
.B jpegtran
works by rearranging the compressed data (DCT coefficients), without
ever fully decoding the image. Therefore, its transformations are lossless:
there is no image degradation at all, which would not be true if you used
.B djpeg
followed by
.B cjpeg
to accomplish the same conversion. But by the same token,
.B jpegtran
cannot perform lossy operations such as changing the image quality. However,
while the image data is losslessly transformed, metadata can be removed. See
the
.B \-copy
option for specifics.
.PP
.B jpegtran
reads the named JPEG/JFIF file, or the standard input if no file is
named, and produces a JPEG/JFIF file on the standard output.
.SH OPTIONS
All switch names may be abbreviated; for example,
.B \-optimize
may be written
.B \-opt
or
.BR \-o .
Upper and lower case are equivalent.
British spellings are also accepted (e.g.,
.BR \-optimise ),
though for brevity these are not mentioned below.
.PP
To specify the coded JPEG representation used in the output file,
.B jpegtran
accepts a subset of the switches recognized by
.BR cjpeg :
.TP
.B \-optimize
Perform optimization of entropy encoding parameters.
.TP
.B \-progressive
Create progressive JPEG file.
.TP
.BI \-restart " N"
Emit a JPEG restart marker every N MCU rows, or every N MCU blocks if "B" is
attached to the number.
.TP
.B \-arithmetic
Use arithmetic coding.
.TP
.BI \-scans " file"
Use the scan script given in the specified text file.
.PP
See
.BR cjpeg (1)
for more details about these switches.
If you specify none of these switches, you get a plain baseline-JPEG output
file. The quality setting and so forth are determined by the input file.
.PP
The image can be losslessly transformed by giving one of these switches:
.TP
.B \-flip horizontal
Mirror image horizontally (left-right).
.TP
.B \-flip vertical
Mirror image vertically (top-bottom).
.TP
.B \-rotate 90
Rotate image 90 degrees clockwise.
.TP
.B \-rotate 180
Rotate image 180 degrees.
.TP
.B \-rotate 270
Rotate image 270 degrees clockwise (or 90 ccw).
.TP
.B \-transpose
Transpose image (across UL-to-LR axis).
.TP
.B \-transverse
Transverse transpose (across UR-to-LL axis).
.IP
The transpose transformation has no restrictions regarding image dimensions.
The other transformations operate rather oddly if the image dimensions are not
a multiple of the iMCU size (usually 8 or 16 pixels), because they can only
transform complete blocks of DCT coefficient data in the desired way.
.IP
.BR jpegtran 's
default behavior when transforming an odd-size image is designed
to preserve exact reversibility and mathematical consistency of the
transformation set. As stated, transpose is able to flip the entire image
area. Horizontal mirroring leaves any partial iMCU column at the right edge
untouched, but is able to flip all rows of the image. Similarly, vertical
mirroring leaves any partial iMCU row at the bottom edge untouched, but is
able to flip all columns. The other transforms can be built up as sequences
of transpose and flip operations; for consistency, their actions on edge
pixels are defined to be the same as the end result of the corresponding
transpose-and-flip sequence.
.IP
For practical use, you may prefer to discard any untransformable edge pixels
rather than having a strange-looking strip along the right and/or bottom edges
of a transformed image. To do this, add the
.B \-trim
switch:
.TP
.B \-trim
Drop non-transformable edge blocks.
.IP
Obviously, a transformation with
.B \-trim
is not reversible, so strictly speaking
.B jpegtran
with this switch is not lossless. Also, the expected mathematical
equivalences between the transformations no longer hold. For example,
.B \-rot 270 -trim
trims only the bottom edge, but
.B \-rot 90 -trim
followed by
.B \-rot 180 -trim
trims both edges.
.IP
If you are only interested in perfect transformation, add the
.B \-perfect
switch:
.TP
.B \-perfect
Fails with an error if the transformation is not perfect.
.IP
For example you may want to do
.IP
.B (jpegtran \-rot 90 -perfect
.I foo.jpg
.B || djpeg
.I foo.jpg
.B | pnmflip \-r90 | cjpeg)
.IP
to do a perfect rotation if available or an approximated one if not.
.PP
We also offer a lossless-crop option, which discards data outside a given
image region but losslessly preserves what is inside. Like the rotate and
flip transforms, lossless crop is restricted by the current JPEG format: the
upper left corner of the selected region must fall on an iMCU boundary. If
this does not hold for the given crop parameters, we silently move the upper
left corner up and/or left to make it so, simultaneously increasing the
region dimensions to keep the lower right crop corner unchanged. (Thus, the
output image covers at least the requested region, but may cover more.)
The adjustment of the region dimensions may be optionally disabled by
attaching an 'f' character ("force") to the width or height number.
The image can be losslessly cropped by giving the switch:
.TP
.B \-crop WxH+X+Y
Crop to a rectangular subarea of width W, height H starting at point X,Y.
.PP
A complementary lossless-wipe option is provided to discard (gray out) data
inside a given image region while losslessly preserving what is outside:
.TP
.B \-wipe WxH+X+Y
Wipe (gray out) a rectangular subarea of width W, height H starting at point
X,Y.
.PP
Attaching an 'f' character ("flatten") to the width number will fill
the region with the average of adjacent blocks, instead of gray out.
.PP
Other not-strictly-lossless transformation switches are:
.TP
.B \-grayscale
Force grayscale output.
.IP
This option discards the chrominance channels if the input image is YCbCr
(ie, a standard color JPEG), resulting in a grayscale JPEG file. The
luminance channel is preserved exactly, so this is a better method of reducing
to grayscale than decompression, conversion, and recompression. This switch
is particularly handy for fixing a monochrome picture that was mistakenly
encoded as a color JPEG. (In such a case, the space savings from getting rid
of the near-empty chroma channels won't be large; but the decoding time for
a grayscale JPEG is substantially less than that for a color JPEG.)
.TP
.BI \-scale " M/N"
Scale the output image by a factor M/N.
.IP
Currently supported scale factors are M/N with all M from 1 to 16, where N is
the source DCT size, which is 8 for baseline JPEG. If the /N part is omitted,
then M specifies the DCT scaled size to be applied on the given input. For
baseline JPEG this is equivalent to M/8 scaling, since the source DCT size
for baseline JPEG is 8.
.B Caution:
An implementation of the JPEG SmartScale extension is required for this
feature. SmartScale enabled JPEG is not yet widely implemented, so many
decoders will be unable to view a SmartScale extended JPEG file at all.
.PP
.B jpegtran
also recognizes these switches that control what to do with "extra" markers,
such as comment blocks:
.TP
.B \-copy none
Copy no extra markers from source file. This setting suppresses all
comments and other metadata in the source file.
.TP
.B \-copy comments
Copy only comment markers. This setting copies comments from the source file,
but discards any other metadata.
.TP
.B \-copy all
Copy all extra markers. This setting preserves metadata
found in the source file, such as JFIF thumbnails, Exif data, and Photoshop
settings. In some files these extra markers can be sizable. Note that this
option will copy thumbnails as-is; they will not be transformed.
.IP
The default behavior is
.BR "\-copy comments" .
(Note: in IJG releases v6 and v6a,
.B jpegtran
always did the equivalent of
.BR "\-copy none" .)
.PP
Additional switches recognized by jpegtran are:
.TP
.BI \-maxmemory " N"
Set limit for amount of memory to use in processing large images. Value is
in thousands of bytes, or millions of bytes if "M" is attached to the
number. For example,
.B \-max 4m
selects 4000000 bytes. If more space is needed, temporary files will be used.
.TP
.BI \-outfile " name"
Send output image to the named file, not to standard output.
.TP
.B \-verbose
Enable debug printout. More
.BR \-v 's
give more output. Also, version information is printed at startup.
.TP
.B \-debug
Same as
.BR \-verbose .
.SH EXAMPLES
.LP
This example converts a baseline JPEG file to progressive form:
.IP
.B jpegtran \-progressive
.I foo.jpg
.B >
.I fooprog.jpg
.PP
This example rotates an image 90 degrees clockwise, discarding any
unrotatable edge pixels:
.IP
.B jpegtran \-rot 90 -trim
.I foo.jpg
.B >
.I foo90.jpg
.SH ENVIRONMENT
.TP
.B JPEGMEM
If this environment variable is set, its value is the default memory limit.
The value is specified as described for the
.B \-maxmemory
switch.
.B JPEGMEM
overrides the default value specified when the program was compiled, and
itself is overridden by an explicit
.BR \-maxmemory .
.SH SEE ALSO
.BR cjpeg (1),
.BR djpeg (1),
.BR rdjpgcom (1),
.BR wrjpgcom (1)
.br
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
The transform options can't transform odd-size images perfectly. Use
.B \-trim
or
.B \-perfect
if you don't like the results.
.PP
The entire image is read into memory and then written out again, even in
cases where this isn't really necessary. Expect swapping on large images,
especially when using the more complex transform options.

63
packages/install/usr/share/man/man1/rdjpgcom.1 Normal file
View File

@@ -0,0 +1,63 @@
.TH RDJPGCOM 1 "13 September 2013"
.SH NAME
rdjpgcom \- display text comments from a JPEG file
.SH SYNOPSIS
.B rdjpgcom
[
.B \-raw
]
[
.B \-verbose
]
[
.I filename
]
.LP
.SH DESCRIPTION
.LP
.B rdjpgcom
reads the named JPEG/JFIF file, or the standard input if no file is named,
and prints any text comments found in the file on the standard output.
.PP
The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
Although the standard doesn't actually define what COM blocks are for, they
are widely used to hold user-supplied text strings. This lets you add
annotations, titles, index terms, etc to your JPEG files, and later retrieve
them as text. COM blocks do not interfere with the image stored in the JPEG
file. The maximum size of a COM block is 64K, but you can have as many of
them as you like in one JPEG file.
.SH OPTIONS
.TP
.B \-raw
Normally
.B rdjpgcom
escapes non-printable characters in comments, for security reasons.
This option avoids that.
.PP
.B \-verbose
Causes
.B rdjpgcom
to also display the JPEG image dimensions.
.PP
Switch names may be abbreviated, and are not case sensitive.
.SH HINTS
.B rdjpgcom
does not depend on the IJG JPEG library. Its source code is intended as an
illustration of the minimum amount of code required to parse a JPEG file
header correctly.
.PP
In
.B \-verbose
mode,
.B rdjpgcom
will also attempt to print the contents of any "APP12" markers as text.
Some digital cameras produce APP12 markers containing useful textual
information. If you like, you can modify the source code to print
other APPn marker types as well.
.SH SEE ALSO
.BR cjpeg (1),
.BR djpeg (1),
.BR jpegtran (1),
.BR wrjpgcom (1)
.SH AUTHOR
Independent JPEG Group

103
packages/install/usr/share/man/man1/wrjpgcom.1 Normal file
View File

@@ -0,0 +1,103 @@
.TH WRJPGCOM 1 "15 June 1995"
.SH NAME
wrjpgcom \- insert text comments into a JPEG file
.SH SYNOPSIS
.B wrjpgcom
[
.B \-replace
]
[
.BI \-comment " text"
]
[
.BI \-cfile " name"
]
[
.I filename
]
.LP
.SH DESCRIPTION
.LP
.B wrjpgcom
reads the named JPEG/JFIF file, or the standard input if no file is named,
and generates a new JPEG/JFIF file on standard output. A comment block is
added to the file.
.PP
The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
Although the standard doesn't actually define what COM blocks are for, they
are widely used to hold user-supplied text strings. This lets you add
annotations, titles, index terms, etc to your JPEG files, and later retrieve
them as text. COM blocks do not interfere with the image stored in the JPEG
file. The maximum size of a COM block is 64K, but you can have as many of
them as you like in one JPEG file.
.PP
.B wrjpgcom
adds a COM block, containing text you provide, to a JPEG file.
Ordinarily, the COM block is added after any existing COM blocks; but you
can delete the old COM blocks if you wish.
.SH OPTIONS
Switch names may be abbreviated, and are not case sensitive.
.TP
.B \-replace
Delete any existing COM blocks from the file.
.TP
.BI \-comment " text"
Supply text for new COM block on command line.
.TP
.BI \-cfile " name"
Read text for new COM block from named file.
.PP
If you have only one line of comment text to add, you can provide it on the
command line with
.BR \-comment .
The comment text must be surrounded with quotes so that it is treated as a
single argument. Longer comments can be read from a text file.
.PP
If you give neither
.B \-comment
nor
.BR \-cfile ,
then
.B wrjpgcom
will read the comment text from standard input. (In this case an input image
file name MUST be supplied, so that the source JPEG file comes from somewhere
else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file
indicator (usually control-D) to terminate the comment text entry.
.PP
.B wrjpgcom
will not add a COM block if the provided comment string is empty. Therefore
\fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file.
.SH EXAMPLES
.LP
Add a short comment to in.jpg, producing out.jpg:
.IP
.B wrjpgcom \-c
\fI"View of my back yard" in.jpg
.B >
.I out.jpg
.PP
Attach a long comment previously stored in comment.txt:
.IP
.B wrjpgcom
.I in.jpg
.B <
.I comment.txt
.B >
.I out.jpg
.PP
or equivalently
.IP
.B wrjpgcom
.B -cfile
.I comment.txt
.B <
.I in.jpg
.B >
.I out.jpg
.SH SEE ALSO
.BR cjpeg (1),
.BR djpeg (1),
.BR jpegtran (1),
.BR rdjpgcom (1)
.SH AUTHOR
Independent JPEG Group