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Document -rgb option in djpeg man page; "gray-scale"="grayscale"

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git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1294 632fc199-4ca6-4c93-a231-07263d6284db
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DRC
2014-05-12 09:09:40 +00:00
parent df3ff573cc 646859004f
commit 461283574a
6 changed files with 24 additions and 21 deletions
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2
README
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@@ -62,7 +62,7 @@ OVERVIEW
This package contains C software to implement JPEG image encoding, decoding, This package contains C software to implement JPEG image encoding, decoding,
and transcoding. JPEG (pronounced "jay-peg") is a standardized compression and transcoding. JPEG (pronounced "jay-peg") is a standardized compression
method for full-color and gray-scale images. JPEG's strong suit is compressing method for full-color and grayscale images. JPEG's strong suit is compressing
photographic images or other types of images that have smooth color and photographic images or other types of images that have smooth color and
brightness transitions between neighboring pixels. Images with sharp lines or brightness transitions between neighboring pixels. Images with sharp lines or
other abrupt features may not compress well with JPEG, and a higher JPEG other abrupt features may not compress well with JPEG, and a higher JPEG

2
cjpeg.1
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@@ -16,7 +16,7 @@ cjpeg \- compress an image file to a JPEG file
compresses the named image file, or the standard input if no file is compresses the named image file, or the standard input if no file is
named, and produces a JPEG/JFIF file on the standard output. named, and produces a JPEG/JFIF file on the standard output.
The currently supported input file formats are: PPM (PBMPLUS color The currently supported input file formats are: PPM (PBMPLUS color
format), PGM (PBMPLUS gray-scale format), BMP, Targa, and RLE (Utah Raster format), PGM (PBMPLUS grayscale format), BMP, Targa, and RLE (Utah Raster
Toolkit format). (RLE is supported only if the URT library is available.) Toolkit format). (RLE is supported only if the URT library is available.)
.SH OPTIONS .SH OPTIONS
All switch names may be abbreviated; for example, All switch names may be abbreviated; for example,

17
djpeg.1
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@@ -55,11 +55,14 @@ default options are chosen for highest quality output.) Currently, this is
equivalent to \fB\-dct fast \-nosmooth \-onepass \-dither ordered\fR. equivalent to \fB\-dct fast \-nosmooth \-onepass \-dither ordered\fR.
.TP .TP
.B \-grayscale .B \-grayscale
Force gray-scale output even if JPEG file is color. Useful for viewing on Force grayscale output even if JPEG file is color. Useful for viewing on
monochrome displays; also, monochrome displays; also,
.B djpeg .B djpeg
runs noticeably faster in this mode. runs noticeably faster in this mode.
.TP .TP
.B \-rgb
Force RGB output even if JPEG file is grayscale.
.TP
.BI \-scale " M/N" .BI \-scale " M/N"
Scale the output image by a factor M/N. Currently the scale factor must be Scale the output image by a factor M/N. Currently the scale factor must be
M/8, where M is an integer between 1 and 16 inclusive, or any reduced fraction M/8, where M is an integer between 1 and 16 inclusive, or any reduced fraction
@@ -74,7 +77,7 @@ emitted if
.B \-colors .B \-colors
or or
.B \-grayscale .B \-grayscale
is specified, or if the JPEG file is gray-scale; otherwise, 24-bit full-color is specified, or if the JPEG file is grayscale; otherwise, 24-bit full-color
format is emitted. format is emitted.
.TP .TP
.B \-gif .B \-gif
@@ -88,12 +91,12 @@ emitted if
.B \-colors .B \-colors
or or
.B \-grayscale .B \-grayscale
is specified, or if the JPEG file is gray-scale; otherwise, 24-bit full-color is specified, or if the JPEG file is grayscale; otherwise, 24-bit full-color
format is emitted. format is emitted.
.TP .TP
.B \-pnm .B \-pnm
Select PBMPLUS (PPM/PGM) output format (this is the default format). Select PBMPLUS (PPM/PGM) output format (this is the default format).
PGM is emitted if the JPEG file is gray-scale or if PGM is emitted if the JPEG file is grayscale or if
.B \-grayscale .B \-grayscale
is specified; otherwise PPM is emitted. is specified; otherwise PPM is emitted.
.TP .TP
@@ -101,8 +104,8 @@ is specified; otherwise PPM is emitted.
Select RLE output format. (Requires URT library.) Select RLE output format. (Requires URT library.)
.TP .TP
.B \-targa .B \-targa
Select Targa output format. Gray-scale format is emitted if the JPEG file is Select Targa output format. Grayscale format is emitted if the JPEG file is
gray-scale or if grayscale or if
.B \-grayscale .B \-grayscale
is specified; otherwise, colormapped format is emitted if is specified; otherwise, colormapped format is emitted if
.B \-colors .B \-colors
@@ -174,7 +177,7 @@ faster and needs less memory, but it produces a lower-quality image.
is ignored unless you also say is ignored unless you also say
.B \-colors .B \-colors
.IR N . .IR N .
Also, the one-pass method is always used for gray-scale output (the two-pass Also, the one-pass method is always used for grayscale output (the two-pass
method is no improvement then). method is no improvement then).
.TP .TP
.BI \-maxmemory " N" .BI \-maxmemory " N"

18
usage.txt
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@@ -17,7 +17,7 @@ INTRODUCTION
These programs implement JPEG image encoding, decoding, and transcoding. These programs implement JPEG image encoding, decoding, and transcoding.
JPEG (pronounced "jay-peg") is a standardized compression method for JPEG (pronounced "jay-peg") is a standardized compression method for
full-color and gray-scale images. full-color and grayscale images.
GENERAL USAGE GENERAL USAGE
@@ -50,7 +50,7 @@ or
This syntax works on all systems, so it is useful for scripts. This syntax works on all systems, so it is useful for scripts.
The currently supported image file formats are: PPM (PBMPLUS color format), The currently supported image file formats are: PPM (PBMPLUS color format),
PGM (PBMPLUS gray-scale format), BMP, Targa, and RLE (Utah Raster Toolkit PGM (PBMPLUS grayscale format), BMP, Targa, and RLE (Utah Raster Toolkit
format). (RLE is supported only if the URT library is available.) format). (RLE is supported only if the URT library is available.)
cjpeg recognizes the input image format automatically, with the exception cjpeg recognizes the input image format automatically, with the exception
of some Targa-format files. You have to tell djpeg which format to generate. of some Targa-format files. You have to tell djpeg which format to generate.
@@ -271,7 +271,7 @@ The basic command line switches for djpeg are:
highest quality output.) Currently, this is equivalent highest quality output.) Currently, this is equivalent
to "-dct fast -nosmooth -onepass -dither ordered". to "-dct fast -nosmooth -onepass -dither ordered".
-grayscale Force gray-scale output even if JPEG file is color. -grayscale Force grayscale output even if JPEG file is color.
Useful for viewing on monochrome displays; also, Useful for viewing on monochrome displays; also,
djpeg runs noticeably faster in this mode. djpeg runs noticeably faster in this mode.
@@ -284,7 +284,7 @@ The basic command line switches for djpeg are:
-bmp Select BMP output format (Windows flavor). 8-bit -bmp Select BMP output format (Windows flavor). 8-bit
colormapped format is emitted if -colors or -grayscale colormapped format is emitted if -colors or -grayscale
is specified, or if the JPEG file is gray-scale; is specified, or if the JPEG file is grayscale;
otherwise, 24-bit full-color format is emitted. otherwise, 24-bit full-color format is emitted.
-gif Select GIF output format. Since GIF does not support -gif Select GIF output format. Since GIF does not support
@@ -294,18 +294,18 @@ The basic command line switches for djpeg are:
-os2 Select BMP output format (OS/2 1.x flavor). 8-bit -os2 Select BMP output format (OS/2 1.x flavor). 8-bit
colormapped format is emitted if -colors or -grayscale colormapped format is emitted if -colors or -grayscale
is specified, or if the JPEG file is gray-scale; is specified, or if the JPEG file is grayscale;
otherwise, 24-bit full-color format is emitted. otherwise, 24-bit full-color format is emitted.
-pnm Select PBMPLUS (PPM/PGM) output format (this is the -pnm Select PBMPLUS (PPM/PGM) output format (this is the
default format). PGM is emitted if the JPEG file is default format). PGM is emitted if the JPEG file is
gray-scale or if -grayscale is specified; otherwise grayscale or if -grayscale is specified; otherwise
PPM is emitted. PPM is emitted.
-rle Select RLE output format. (Requires URT library.) -rle Select RLE output format. (Requires URT library.)
-targa Select Targa output format. Gray-scale format is -targa Select Targa output format. Grayscale format is
emitted if the JPEG file is gray-scale or if emitted if the JPEG file is grayscale or if
-grayscale is specified; otherwise, colormapped format -grayscale is specified; otherwise, colormapped format
is emitted if -colors is specified; otherwise, 24-bit is emitted if -colors is specified; otherwise, 24-bit
full-color format is emitted. full-color format is emitted.
@@ -367,7 +367,7 @@ Switches for advanced users:
The one-pass method is faster and needs less memory, The one-pass method is faster and needs less memory,
but it produces a lower-quality image. -onepass is but it produces a lower-quality image. -onepass is
ignored unless you also say -colors N. Also, ignored unless you also say -colors N. Also,
the one-pass method is always used for gray-scale the one-pass method is always used for grayscale
output (the two-pass method is no improvement then). output (the two-pass method is no improvement then).
-maxmemory N Set limit for amount of memory to use in processing -maxmemory N Set limit for amount of memory to use in processing

4
wrgif.c
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@@ -218,7 +218,7 @@ put_3bytes (gif_dest_ptr dinfo, int val)
LOCAL(void) LOCAL(void)
emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap) emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap)
/* Output the GIF file header, including color map */ /* Output the GIF file header, including color map */
/* If colormap==NULL, synthesize a gray-scale colormap */ /* If colormap==NULL, synthesize a grayscale colormap */
{ {
int BitsPerPixel, ColorMapSize, InitCodeSize, FlagByte; int BitsPerPixel, ColorMapSize, InitCodeSize, FlagByte;
int cshift = dinfo->cinfo->data_precision - 8; int cshift = dinfo->cinfo->data_precision - 8;
@@ -270,7 +270,7 @@ emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap)
put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift); put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift);
} }
} else { } else {
/* Create a gray-scale map of num_colors values, range 0..255 */ /* Create a grayscale map of num_colors values, range 0..255 */
put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1)); put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1));
} }
} else { } else {

2
wrtarga.c
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@@ -73,7 +73,7 @@ write_header (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo, int num_colors)
targaheader[17] = 0x20; /* Top-down, non-interlaced */ targaheader[17] = 0x20; /* Top-down, non-interlaced */
if (cinfo->out_color_space == JCS_GRAYSCALE) { if (cinfo->out_color_space == JCS_GRAYSCALE) {
targaheader[2] = 3; /* image type = uncompressed gray-scale */ targaheader[2] = 3; /* image type = uncompressed grayscale */
targaheader[16] = 8; /* bits per pixel */ targaheader[16] = 8; /* bits per pixel */
} else { /* must be RGB */ } else { /* must be RGB */
if (num_colors > 0) { if (num_colors > 0) {