term% cat index.txt JPG(1) General Commands Manual JPG(1)
NAME
jpg, gif, png, ppm, bmp, v210, yuv, ico, togif, toppm, topng, toico -
view and convert pictures
SYNOPSIS
jpg [ -39cdefFkJrtv ] [ file ... ]
gif [ -39cdektv ] [ file ... ]
png [ -39cdektv ] [ file ... ]
ppm [ -39cdektv ] [ file ... ]
bmp [ file ]
v210 [ -39cdektv ] [ file ... ]
yuv [ file ]
togif [ -c comment ] [ -l loopcount ] [ -d msec ] [ -t transindex ] [
file ... [ -d msec ] file ... ]
toppm [ -c comment ] [ file ]
topng [ -c comment ] [ [ -g gamma ] [ file ]
ico [ file ]
toico [ file ... ]
DESCRIPTION
These programs read, display, and write image files in public formats.
Jpg, gif, png, ppm, bmp, v210, and yuv read files in the corresponding
formats and, by default, display them in the current 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 im‐
ages files, convert them to GIF, PPM, or PNG, and write them to stan‐
dard 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 inter‐
face, use page(1), which invokes these programs to convert the images
to standard 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 im‐
prove the appearance of images on color-mapped displays, typi‐
cally 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 if the
display has true RGB color.
-d Suppress display of the image; this is set automatically by any
of the following options:
-c Convert the image to a Plan 9 representation, as defined by im‐
age(6), and write it to standard output.
-9 Like -c, but produce an uncompressed image. This saves process‐
ing time, particularly when the output is being piped to another
program such as page(1), since it avoids compression and decom‐
pression.
-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 originally
grey-scale.
Jpg has two extra options used to process the output of the LML video
card:
-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 represent‐
ing 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 capability. 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 ren‐
dered. 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.
Ico displays a Windows icon (.ico) file. If no file is specified, ico
reads from standard input. Icon files contain sets of icons repre‐
sented by an image and a mask. Clicking the right button pops up a
menu that lets you write any icon's image as a Plan 9 image (widthx‐
height.image), write any icon's mask as a Plan 9 image (widthx‐
height.mask), or exit. Selecting one of the write menu items yields a
sight cursor. Move the sight over the icon and right click again to
write.
Toico takes a list of Plan 9 image files (or standard input) and cre‐
ates a single icon file. The masks in the icon file will be the white
space in the image. The icon file is written to standard output.
SOURCE
/sys/src/cmd/jpg
SEE ALSO
page(1), image(6).
http://www.w3.org/Graphics/JPEG/itu-t81.pdf
http://www.w3.org/Graphics/GIF/spec-gif89a.txt
http://www.w3.org/TR/2003/REC-PNG-20031110
http://netpbm.sourceforge.net/doc/ppm.html
http://en.wikipedia.org/wiki/Windows_bitmap
http://en.wikipedia.org/wiki/Yuv
BUGS
Writing an animated GIF using togif is a clumsy undertaking.
JPG(1)