Blame - djpeg.1 - platform/external/libjpeg-turbo

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Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	1	.TH DJPEG 1 "28 February 1992"
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	2	.SH NAME
				3	djpeg \- decompress a JPEG file to an image file
				4	.SH SYNOPSIS
				5	.B djpeg
				6	[
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	7	.B \-GPRTgD1bd
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	8	]
				9	[
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	10	.BI \-q " colors"
				11	]
				12	[
				13	.BI \-m " memory"
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	14	]
				15	[
				16	.I filename
				17	]
				18	.LP
				19	.SH DESCRIPTION
				20	.LP
				21	.B djpeg
				22	decompresses the named JPEG file, or the standard input if no file is named,
				23	and produces an image file on the standard output. PPM, GIF, Targa, or RLE
				24	output format can be selected. (RLE is supported only if the URT library is
				25	available.)
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	26	.SH OPTIONS
				27	.TP
				28	.B \-G
				29	Select GIF output format (implies
				30	.BR \-q ,
				31	with default of 256 colors).
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	32	.TP
				33	.B \-P
				34	Select PPM or PGM output format (this is the default). PGM is emitted if the
				35	JPEG file is gray-scale or if
				36	.B \-g
				37	is specified.
				38	.TP
				39	.B \-R
				40	Select RLE output format. Requires URT library.
				41	.TP
				42	.B \-T
				43	Select Targa output format. Gray-scale format is emitted if the JPEG file is
				44	gray-scale or if
				45	.B \-g
				46	is specified; otherwise, colormapped format is emitted if
				47	.B \-q
				48	is specified; otherwise, 24-bit full-color format is emitted.
				49	.TP
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	50	.B \-g
				51	Force gray-scale output even if input is color.
				52	.TP
				53	.BI \-q " N"
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	54	Quantize to N colors. This reduces the number of colors in the output image
				55	so that it can be displayed on a colormapped display or stored in a
				56	colormapped file format. For example, if you have an 8-bit display, you'd
				57	need to quantize to 256 or fewer colors.
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	58	.TP
				59	.B \-D
				60	Do not use dithering in color quantization. By default, Floyd-Steinberg
				61	dithering is applied when quantizing colors, but on some images dithering may
				62	result in objectionable "graininess". If that happens, you can turn off
				63	dithering with
				64	.BR \-D .
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	65	.B \-D
				66	is ignored unless you also say
				67	.B \-q
				68	or
				69	.BR \-G .
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	70	.TP
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	71	.B \-1
				72	Use one-pass instead of two-pass color quantization. The one-pass method is
				73	faster and needs less memory, but it produces a lower-quality image.
				74	.B \-1
				75	is ignored unless you also say
				76	.B \-q
				77	or
				78	.BR \-G .
				79	Also, the one-pass method is always used for gray-scale output (the two-pass
				80	method is no improvement then).
				81	.TP
				82	.B \-b
				83	Perform cross-block smoothing. This is quite memory-intensive and only seems
				84	to improve the image at low quality settings (\fB\-Q\fR 10 to 20 or so).
				85	At normal
				86	.B \-Q
				87	settings it may make the image worse.
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	88	.TP
				89	.B \-d
				90	Enable debug printout. More
				91	.BR \-d 's
				92	give more output. Also, version information is printed at startup.
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	93	.TP
				94	.BI \-m " memory"
				95	Set limit for amount of memory to use in processing large images. Value is
				96	in thousands of bytes, or millions of bytes if "M" is attached to the
				97	number. For example,
				98	.B \-m 4m
				99	selects 4000000 bytes. If more space is needed, temporary files will be used.
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	100	.SH EXAMPLES
				101	.LP
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	102	This example decompresses the JPEG file foo.jpg, quantizes to 256 colors,
				103	and saves the output in GIF format in foo.gif:
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	104	.IP
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	105	.B djpeg \-G
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	106	.I foo.jpg
				107	.B >
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	108	.I foo.gif
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	109	.SH SEE ALSO
				110	.BR cjpeg (1)
				111	.br
Thomas G. Lane	4a6b730	1992-03-17 00:00:00 +0000	[diff] [blame^]	112	.BR ppm (5),
				113	.BR pgm (5)
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	114	.br
				115	Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
				116	Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
				117	.SH AUTHOR
				118	Independent JPEG Group
				119	.SH BUGS
Thomas G. Lane	bd543f0	1991-12-13 00:00:00 +0000	[diff] [blame]	120	Arithmetic coding is not supported for legal reasons.
				121	.PP
				122	Not as fast as we'd like.