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PICO(1) General Commands Manual PICO(1) NAME pico - graphics editor SYNOPSIS pico [ -mfto ] [ -wN -hN ] [ files ] DESCRIPTION Pico is an interactive editor for grey-scale and color images. Editing operations are expressed in a C-like style. The options are -mn Display on a Metheus frame buffer, /dev/omn. A missing n is taken to be 0. -f Display on an Itoh frame buffer, /dev/iti0. -t Show parse trees for expressions; toggled by the interactive command -o Turn off the optimizer; toggled by Files are referred to in expressions as $n, where n is the basename or an integer, see f below. Otherwise file names are given as strings in double quotes, which may be elided from names that do not contain In general, the result of the previous edit operation is available un- der the name The destination of the current operation is called Pico handles images with coordinates (0,0) in the upper left hand cor- ner and (X,Y) in the lower right. Brightnesses range from 0 (black) to Z (white, Z=255). The quantities X,Y,Z may be used in expressions and set by options: -w n Set the width X of the work area to n pixels, default 511. -h n Set the height Y, default 511. Pico reads commands from the standard input: help Give a synopsis of commands and functions. a file a x y w d file Attach a new file. Optional parameters x and y give the origin of a subrectangle in the work buffer; w and d define width and depth of the image as stored in the file. d file d $n Delete (close) the file. h file Read header information from the file. r file Read commands from file as if they were typed on the terminal. Can not be done recursively. w file w - file Write the file, restricted to the current window (see below). Use pico format by default. With a minus flag, write a header- less image (red channel only, if picture is colored); see also picfile(5). nocolor color Set the number of channels updated in the work buffer to 1 (black and white) or 3 (red, green, blue). window x y w d Restrict the work area to a portion of the work buffer with the upper left corner at (x,y), and the lower right at (x+w,y+d). get file get $n The picture file is (re)opened and read into the work area. f Show names, sizes, and file numbers of open files. faster slower In slow display the screen is updated once per pixel computed; in fast display (default), once per line of pixels. show name Show symbol table information, such as the current value of variables. If name is omitted, the whole symbol table is shown. functions Print information on all user defined and builtin functions. def name ( args ) { program } Define a function, with optional arguments. Variables are de- clared in these styles: int var; global int var; array var[N]; global array var[N]; x expr Execute the expression in a default loop over all pixels in the current window. x {program } Execute the program. The program must define its own control flow. q Quit. EXAMPLES Get a work buffer that exactly fills a Metheus screen. a "/tmp/images/rob" Make a file accessible. It will be known henceforth as Direct attention to a 512x512 subrectangle in the middle of a 3072x512 image stored in a file named junk, and read it into the workspace. 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];} Three ways to make a negative image. Note the defaults on con- trol flow and array indexing. window 0 0 256 256 x new = $1[xclamp(x*2), yclamp(y*2)] Scale a 512x512 image to one quarter of the screen. The built- in functions and guard against indexing out of range. x { printf("current value of %s[%d]:\t%d\n", "histo", 128, hist[128]); } Turn off the default control flow (curly braces) and use the builtin function printf to check the value of an array element. SEE ALSO bcp(1), imscan(1), flicks(9.1), rebecca(9.1), picfile(5), flick- file(9.5) G. J. Holzmann, `PICO Tutorial', this manual, Volume 2 G. J. Holzmann, Beyond Photography--the Digital Darkroom, Prentice- Hall, 1988 PICO(1)