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JPEG version 1.2
1) Printing documentation:
Documentation is in the PostScript file doc.ps. It is about 50 pages
long.
2) Making the program.
The makefile should be setup for most UNIX systems as is. Simply type
"make" in the source code directory.
For SYSV only libraries, substitute the first line in the makefile
#DEFINES = -DSYSV -DNOTRUNCATE for
#DEFINES
which allows for SYSV libraries to be used instead. The NOTRUNCATE
flag avoids the lack of the ftruncate() call used in io.c.
For some gcc versions on Solaris, need to include <ftype.h> not
<sys/ftype.h> otherwise O_RDONLY etc. are not defined; define
FCNTL_FOR_O_RDONLY. This also may need to be added to the lexer.c
output by lex to make it compile.
Caution: For the compilation, the lexer.l file should be older than
the lexer.c file otherwise many machines will try and lex the lexer.l
file (thus clobbering potentially the lexer.c file). In general, the
tar will take out the lexer.l file first (it's specified to do that),
so there shouldn't be any problems unless the directory is _copied_
and then remade, in which case, the lexer.c file will be older because
is lexically of lesser value than lexer.l. This is a potential bug.
For recent MacOS versions, need to changer lexer.l to specify
"%option noyywrap" outside the "%{ ...}%" section and remove the
"#define yywrap() 1" definition.
3) Testing the program.
Two small test files are nonint.jpg and blkint.jpg. If you wish to
extract them, type
jpeg -d -s nonint.jpg
jpeg -d -s blkint.jpg
The resulting files should be in
nonint.jpg.1 nonint.jpg.2 nonint.jpg.3
blkint.jpg.1 blkint.jpg.2 blkint.jpg.3
These files are raw raster-scan component files 128x128 for the Y
(.1), 64x128 for the U(.2) and V(.3).
4) Displaying the decompressed files.
The decompressed *.1 *.2 *.3 files may be displayed through the
program "cv" which may be obtained by anonymous ftp from
havefun.stanford.edu:pub/cv/CVv1.1.tar.Z. If the program is in your
current directory search-path, type
cv -iw 128 -ih 128 nonint.jpg -SF
or
cv -iw 128 -ih 128 blkint.jpg -SF
5) Recompressing the sample files
Use the following commands to recompress the nonint.jpg.* component
files into the nonint.jpg2 file:
jpeg -iw 128 -ih 128 -n -hf 2 nonint.jpg.1 nonint.jpg.2 nonint.jpg.3 \
-s nonint2.jpg
Use the following commands to recompress the blkint.jpg.* component
files into the blkint.jpg2 file:
jpeg -iw 128 -ih 128 -hf 2 blkint.jpg.1 blkint.jpg.2 blkint.jpg.3 \
-s blkint2.jpg
Surprisingly, recompressing and decompressing the blkint should yield
the same result. (The nonint files will not yield the same result -
but very close - since the non-interleaved mode defaults to using the
LUMINANCE quantization matrix for the first color component of each
scan.) See the documentation for more details on other parameters.
6) Some short interpreted programs for the encoder: (See Chapter 4 of
the documentation behind these programs).
test.huff test.3stream test.q
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