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The Independent JPEG Group's JPEG software v8d

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This commit is contained in:
Guido Vollbeding
2012-01-15 00:00:00 +00:00
committed by DRC
parent c39ec149e8
commit 5829cb2398
40 changed files with 1437 additions and 734 deletions
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29
cjpeg.1
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@@ -1,4 +1,4 @@
.TH CJPEG 1 "14 November 2010"
.TH CJPEG 1 "28 August 2011"
.SH NAME
cjpeg \- compress an image file to a JPEG file
.SH SYNOPSIS
@@ -49,6 +49,14 @@ 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.
Use this switch in combination with the
.BI \-block " N"
switch (see below) for lossless JPEG coding.
.TP
.B \-optimize
Perform optimization of entropy encoding parameters. Without this, default
encoding parameters are used.
@@ -155,6 +163,12 @@ 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).
@@ -162,9 +176,10 @@ 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).
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.
.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 \-dct int
Use integer DCT method (default).
@@ -233,12 +248,6 @@ visibly blur the image, however.
.PP
Switches for wizards:
.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
.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