JPG(1) JPG(1)
NAME
jpg, gif, png, ppm, togif, toppm, topng - view and convert
pictures
SYNOPSIS
jpg [ -39cdefFkJrtv ] [ file ... ]
gif [ -39cdektv ] [ file ... ]
png [ -39cdektv ] [ file ... ] ppm [ -39cdektv ] [ file ...
]
togif [ -c comment ] [ -l loopcount ] [ -d msec ] [ -t
transindex ] [ file ... [ -d msec ] file ... ]
toppm [ -c comment ] [ file ]
topng [ -c comment ] [ [ -g gamma ] [ file ]
DESCRIPTION
These programs read, display, and write image files in pub-
lic formats. Jpg, gif, png, and ppm read files in the cor-
responding formats and, by default, display them in the cur-
rent window; options cause them instead to convert the
images to Plan 9 image format and write them to standard
output. Togif, Toppm, and topng read Plan 9 images files,
convert them to GIF, PPM, or PNG, and write them to standard
output.
The default behavior of jpg, gif, and ppm is to display the
file, or standard input if no file is named. Once a file is
displayed, typing a character causes the program to display
the next image. Typing a q, DEL, or control-D exits the
program. For a more user-friendly interface, use page(1),
which invokes these programs to convert the images to stan-
dard format, displays them, and offers scrolling, panning,
and menu-driven navigation among the files.
These programs share many options:
-e Disable Floyd-Steinberg error diffusion, which is used
to improve the appearance of images on color-mapped
displays, typically with 8 bits per pixel. Primarily
useful for debugging; if the display has true RGB
color, the image will be displayed in full glory.
-k Convert and display the image as a black and white
(really grey-scale) image.
-v Convert the image to an RGBV color-mapped image, even
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JPG(1) JPG(1)
if the display has true RGB color.
-d Suppress display of the image; this is set automati-
cally by any of the following options:
-c Convert the image to a Plan 9 representation, as
defined by image(6), and write it to standard output.
-9 Like -c, but produce an uncompressed image. This saves
processing time, particularly when the output is being
piped to another program such as page(1), since it
avoid compression and decompression.
-t Convert the image, if it is in color, to a true color
RGB image.
-3 Like -t, but force the image to RGB even if it is orig-
inally grey-scale.
Jpg has two extra options used to process the output of the
LML video card (see lml(1)):
-f Merge two adjacent images, which represent the two
fields of a video picture, into a single image.
-F The input is a motion JPEG file, with multiple images
representing frames of the movie. Sets -f.
The togif and toppm programs go the other way: they convert
from Plan 9 images to GIF and PPM, and have no display capa-
bility. Both accept an option -c to set the comment field
of the resulting file. If there is only one input picture,
togif converts the image to GIF format. If there are many
files, though, it will assemble them into an animated GIF
file. The options control this process:
-lloopcount
By default, the animation will loop forever; loopcount
specifies how many times to loop. A value of zero
means loop forever and a negative value means to stop
after playing the sequence once.
-dmsec
By default, the images are displayed as fast as they
can be rendered. This option specifies the time, in
milliseconds, to pause while displaying the next named
file.
Gif translates files that contain a `transparency' index by
attaching an alpha channel to the converted image.
SOURCE
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JPG(1) JPG(1)
/sys/src/cmd/jpg
SEE ALSO
lml(1), page(1), image(6).
BUGS
Writing an animated GIF using togif is a clumsy undertaking.
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