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Packages commonly used interactions with the image currently displayed
on the LEXIDATA. The program has several modes of operation which are
described briefly below. The user interaction is performed entirely
with the Lexidata trackerball/joystick and switches. (Each switch has
a specific meaning which is common to all the Lexidata programs -
details are in the next section).
There are six modes of operation, and the MODE switch is used to
cycle through them. The initial mode is ``Profile'', followed by ``Stats'',
``List'', ``Zoom'', ``Cursor'', and ``Dist'' respectively. The RESET switch
unzooms the image only when in ZOOM mode and then resets everything back
to its default value. The EXIT switch always causes immediate program exit.
The behaviour of the remaining switches, READ, DOWN, UP, is described for
each mode : -
- PROFILE - The read switch causes a Profile to be drawn from the
previous cursor position to the current position. Currently only horizontal
and vertical profiles are permitted. The UP and down switches
control scaling - DOWN halves the cutoff, UP doubles it.
- STATS - The READ switch causes statistics of a rectangular
neighbourhood of the current position to be listed on the
terminal. These include a sky estimate based on the rim of
the box, estimate of sky subtracted flux, standard deviations
and maximum/minimum pixel values within the box. The UP and
DOWN switches control the box size - initially it is of side
21 and DOWN decreases it by 2, UP increases it by 2. Two
passes are made through the data so that sources in the rim
can be clipped out before estimating the sky background and
noise. The level of clipping is controlled by CLIPSIG (default
is 2.0). The width of the rim is controlled by RIMWIDTH (default
is 10) and the number of
above the noise for a
believable source by NUMSIG (default is 10.0). The defaults
can be changed if required as shown below.
Examples
Adam:> PHOT RIMWIDTH = 10 CLIPSIG = 3.0 NUMSIG = 3.0
- LIST - The READ switch causes the pixel values of a rectangular
neighbourhood to be listed on the terminal. The box is the
same one as used by STATS and its size is controlled in
the same way using the UP and DOWN switches.
- ZOOM - The READ switch causes the image to be zoomed about the
current position with the current zoom factor. The UP and
DOWN switches control the current ZOOM factor - initially
it is whatever it was on entry to PHOTOM and DOWN decreases
it by 1, UP increases it by 1.
- CURSOR - The READ switch merely echoes the current position in pixel
and user coordinates, plus the corresponding data value.
In fact this information is given in all modes. The UP and
DOWN switches control the box size in the same way as the
STATS and LIST switches.
- DIST - The READ switch causes the distance between the current
position and the last position to be calculated (in pixels)
and listed on the terminal. The UP and DOWN switches control
the box size in the same way as the STATS and LIST switches.
Parameters
There are some, but they should not normally be necessary when
running within the CCD system.
Examples
Adam:> PHOTOM
Notes
PHOTOM, in common with all the Lexidata programs, will automatically
use the current image, i.e. the one that has been most recently displayed
from the CCD.
PHOTOM uses the BIAS value given at startup when it estimates line
centres. A better value can be estimated using PHOTOM in STATS mode
or else the STATS facility. BIAS in as ACL variable so can be updated
by typing BIAS=< newbias >, or run the procedure BIAS and answer the
prompt - this has the advantage of giving the current bias first.
The pixel coordinates of the last two points selected in PHOTOM are
written as ACL variables PHOTOM_PXX1, PHOTOM_PXY1, PHOTOM_PXX2 and
PHOTOM_PXY2. Thus PHOTOM can be used in a procedure as an easy way
of getting two points selected by the user.
Previous: QDI(PARM)/DI(PARM) - Enquire and alter display parameters
Up: LEXIDATA DISPLAY OPERATIONS
Next: MOVESTAR - Put an object onto a specified area of the chip
Previous Page: QDI(PARM)/DI(PARM) - Enquire and alter display parameters
Next Page: MOVESTAR - Put an object onto a specified area of the chip