path: root/static/unix-v10/man1/pico.1

.TH PICO 1
.CT 1 editor graphics
.SH NAME
pico \(mi graphics editor
.SH SYNOPSIS
.B pico
[
.B -mfto
]
[
.B -wN -hN
]
[
.I files
]
.SH DESCRIPTION
.I Pico
is an interactive editor for grey-scale and color images.
Editing operations are expressed in a C-like style.
The options are
.TP \w'\f5slower\ 'u
.BI -m n
Display on a Metheus frame buffer,
.BI  /dev/om n.
A missing
.I n
is taken to be 0.
.TP
.B -f
Display on an Itoh frame buffer,
.BR /dev/iti0 .
.TP
.B -t
Show parse trees for expressions; toggled by the interactive command
.LR tree .
.TP
.B -o
Turn off the optimizer; toggled by
.LR optim .
.PP
Files are referred to in expressions as
.BI $ n,
where 
.I n
is the basename or an integer,
see
.B f
below.
Otherwise file names are given as strings in double quotes,
which may be elided from names that do not contain
.LR / .
.LP
In general, the result of the previous edit
operation is available under the name
.LR old .
The destination
of the current operation is called
.LR new .
.LP
.I Pico
handles images with coordinates (0,0) in the upper left hand corner
and
.RB ( X , Y )
in the lower right.
Brightnesses range from 0 (black) to 
.BR Z 
(white, 
.BR Z =255).
The quantities
.BR X , Y , Z
may be used in expressions and set by options:
.TP \w'\f5slower\ 'u
.BI -w " n
Set the width 
.B X
of the work area to
.I n
pixels, default 511.
.TP
.BI -h " n
Set the height
.BR Y ,
default 511.
.PP
.LP
.I Pico
reads commands from the standard input:
.TP
.B help
Give a synopsis of commands and functions.
.TP
.BI a " file
.br
.ns
.TP
.BI a " x y w d file"
Attach a new file.
Optional parameters
.I x
and 
.I y
give the origin of a subrectangle in the work buffer;
.I w
and
.I d
define width and depth of the image as stored in the file.
.TP
.BI d " file"
.PD0
.TP
.BI "d $" n
Delete (close) the file.
.PD
.TP
.BI h " file"
Read header information from the file.
.TP
.BI r " file"
Read commands from
.I file
as if they were typed on the terminal.
Can not be done recursively.
.TP
.BI w " file
.br
.ns
.TP
.BI "w - " file
Write the file, restricted to the current window
(see below).
Use
.I pico
format by default.
With a minus flag,
write a headerless image
(red channel only, if picture is colored); see also
.IR picfile (5).
.TP
.B nocolor
.PD0
.TP
.B color
Set the number of channels updated in the work buffer to 1
(black and white) or 3 (red, green, blue).
.PD
.TP
.BI window " x y w d"
Restrict the work area to a portion of the
work buffer with the upper left corner at
.RI ( x,y ),
and the lower right at
.RI ( x+w, y+d ).
.TP
.BI get " file"
.br
.ns
.TP
.BI "get $" n
The picture file is (re)opened and read into the work area.
.TP
.B f
Show names, sizes, and file numbers of open files.
.TP
.B faster
.br
.ns
.TP
.B slower
In slow display the screen is updated once per pixel computed;
in fast display (default), once per line of pixels.
.TP
.BI show " name"
Show symbol table information, such as the current value of variables.
If 
.I name
is omitted, the whole symbol table is shown.
.TP
.B functions
Print information on all user defined and builtin functions.
.TP
.BI def " name \fB(\fI args \fB) {\fI program \fB}"
Define a function, with optional arguments.
Variables are declared in these styles:
.PD0
.IP
.EX
int var;
global int var;
array var[N];
global array var[N];
.EE
.PD
.TP
.BI x " expr"
Execute the expression in a default loop over all pixels in the
current window.
.TP
.BI "x {" program " }"
Execute the
.I program.
The program must define its own control flow.
.TP
.B q
Quit.
.SH EXAMPLES
.TP
.L "pico -w1280 -h1024 -m5"
Get a work buffer that exactly fills a Metheus screen.
.TP
.L
a "/tmp/images/rob"
Make a file accessible.
It will be known henceforth as
.LR $rob .
.PP
.EX
.L a 1280 0 3072 512 junk
.L get $junk
.EE
.PD0
.IP
Direct attention to a 512\(mu512 subrectangle in the middle
of a 3072\(mu512 image stored in a file named junk,
and read it into the workspace.
.LP
.EX
x new = Z - old
x new[x,y] = Z - old[x,y]
x {for(x=0; x<=X; x++) for(y=0; y<=Y; y++) new[x,y] = Z-old[x,y];}
.EE
.PD0
.IP
Three ways to make a negative image.
Note the defaults on control flow
and array indexing.
.PD
.LP
.EX
window 0 0 256 256
x new = $1[xclamp(x*2), yclamp(y*2)]
.EE
.PD0
.IP
Scale a 512\(mu512 image to one quarter of the screen.
The built-in functions
.L xclamp
and
.L yclamp
guard against indexing out of range.
.PD
.LP
.EX
x { printf("current value of %s[%d]:\et%d\en", "histo", 128, hist[128]); }
.EE
.PD0
.IP
Turn off the default control flow (curly braces) and use the
builtin function printf to check the value of an array element.
.SH "SEE ALSO"
.IR bcp (1),
.IR imscan (1),
.IR flicks (9.1), 
.IR rebecca (9.1), 
.IR picfile (5), 
.IR flickfile (9.5)
.br
G. J. Holzmann,
`PICO Tutorial',
this manual, Volume 2
.br
G. J. Holzmann,
.I Beyond Photography\(emthe Digital Darkroom,
Prentice-Hall, 1988