tv command

SYNOPSIS

tv fits_file [span=] [zero=] [zoom=] [xo=] [yo=] [nofork] [debug] [baby|hours] [equinox=] [box=] [gamma=] [pid] [invert] [label=]

DESCRIPTION

This program displays the image in the file specified in the command line onto the TV display. The data are processed as follows:

pixel = (data - zero)*NCOLOR/span

where NCOLOR is the number of colors that the monitor can display.

If no span or zero are specified, then a few pixel values are sampled, and the span and zero are adjusted automatically (their values are printed on the text screen).

The data are shown starting in the upper left hand corner of the display unless modified by the xo and yo switches.

The zoom modifier can be used to show an expanded or shrunken view of the data. Non-integral values are rounded to the nearest integer. If the zoom value is less than 0.5, then the reciprocal of the value (rounded to the nearest integer) is used as a binning factor; thus, zoom=0.25 yields an image binned by a factor of four.

TV usally spawns a background process and returns your prompt. If you wish to wait until the window is terminated before getting the prompt, use the nofork option.

If WCS data are available, the Right Ascension and Declination are displayed. Decimal degrees are shown, unless the baby option is selected at which time, sexagesimal format will be used. The option hours has ra in decimal hours (for some stupid reason). The coordinate equinox can be overriden by the command line equinox option.

gamma= sets the conversion of ADUs to brightness units using a power law. The default is 1.0.

pid - causes the process ID to be printed out.

label changes the name of the label at the top of the display. The default value is the name of the FITs file.

WINDOW BEHAVIOR

As each image is displayed, a new process is created to run inside the window. Thus, control will pass immediately back to the shell after the tv command is typed, even before the image is fully shown. You can use any X-Windows Manager functions to move, hide/show, or cancel an image window.
MOUSE CONTROL

Left -toggles continuous update of cursor position and pixel value

Middle -changes color map depending on cursor position

Right -kills window process and deletes window

KEYBOARD CONTROL
Pressing the following keys causes the image to react in some way.

z-zooms in on the current position of the cursor, creating a new window which has a larger zoom value (but the same zero and span).

Z -zooms out, again creating a new window, but this time with a smaller zoom value.

LeftArrow -moves the cursor one screen pixel left.

RightArrow moves cursor one screen pixel right.

UpArrow -moves cursor one screen pixel up.

DownArrow moves cursor one screen pixel down.

h - prints list of command

c- c does column plot

C - does row plot

r - does radial plot

p - prints row column data to stdout

q - quits the program

EXAMPLES
tv crab - displays the file `crab.fits' in the upper left-hand corner of the screen. Automatically finds the span and zero by looking at some pixels from the file.
tv virgo 500 200 zoom=2 - starting at 200 units to the right of the upper left-hand corner of the screen, displays the part of the image `virgo' which is within box 1. The zero value is 200, and span 500. The file is displayed so that each pixel in the image covers a two-by-two pixel area on the screen.
tv virgo zoom=0.5 - Displays the image in `virgo', using automatic zero and span, in the upper left-hand corner of the screen. The image is crunched down so that each pixel on the screen represents a two-by-two pixel area on the image.
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