TH JPG 1
SH NAME
jpg, gif, png, ppm, togif, toppm, topng \- view and convert pictures
SH SYNOPSIS
B jpg
[
B -39cdefFkJrtv
] [
I file ...
]
PP
B gif
[
B -39cdektv
] [
I file ...
]
PP
B png
[
B -39cdektv
] [
I file ...
]
B ppm
[
B -39cdektv
] [
I file ...
]
PP
B togif
[
B -c
I comment
] [
B -l
I loopcount
] [
B -d
I msec
] [
B -t
I transindex
] [
I file ...
[
B -d
I msec
]
I file ...
]
PP
B toppm
[
B -c
I comment
] [
I file
]
PP
B topng
[
B -c
I comment
] [
[
B -g
I gamma
] [
I file
]
SH DESCRIPTION
These programs read, display, and write image files in public formats.
IR Jpg ,
IR gif ,
IR png ,
and
I ppm
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.
IR Togif ,
IR Toppm ,
and
I topng
read Plan 9 images files, convert them to GIF, PPM, or PNG, and write them to standard output.
PP
The default behavior of
IR jpg ,
IR gif ,
and
IR ppm
is to display the
IR 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
BR q ,
DEL, or control-D exits the program.
For a more user-friendly interface, use
IR 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.
PP
These programs share many options:
TP
B -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.
TP
B -k
Convert and display the image as a black and white (really grey-scale) image.
TP
B -v
Convert the image to an RGBV color-mapped image, even if the
display has true RGB color.
TP
B -d
Suppress display of the image; this is set automatically by
any of the following options:
TP
B -c
Convert the image to a Plan 9 representation, as defined by
IR image (6),
and write it to standard output.
TP
B -9
Like
BR -c ,
but produce an uncompressed image.
This saves processing time, particularly when the output is
being piped to another program such as
IR page (1),
since it avoids compression and decompression.
TP
B -t
Convert the image, if it is in color, to a true color RGB image.
TP
B -3
Like
BR -t ,
but force the image to RGB even if it is originally grey-scale.
PD
PP
I Jpg
has two extra options used to process the output of the LML
video card (see
IR lml (1)):
TP
B -f
Merge two adjacent images, which represent the two fields of a video picture,
into a single image.
TP
B -F
The input is a motion JPEG file, with multiple images representing frames of the movie. Sets
BR -f .
PD
PP
The
IR togif
and
IR 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
B -c
to set the comment field of the resulting file.
If there is only one input picture,
I togif
converts the image to GIF format.
If there are many
IR files ,
though, it will assemble them into an animated GIF file.
The options control this process:
TP
BI -l loopcount
By default, the animation will loop forever;
I 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.
TP
BI -d msec
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
IR file .
PP
I Gif
translates files that contain a `transparency' index by attaching
an alpha channel to the converted image.
SH SOURCE
B /sys/src/cmd/jpg
SH "SEE ALSO"
IR lml (1),
IR page (1),
IR image (6).
SH BUGS
Writing an animated GIF using
I togif
is a clumsy undertaking.
