- NAME
UNZOOM_XY
- PURPOSE
Converts X, Y position on the image display to the the X,Y position
on the corresponding data array. (These positions are identical
only for an unroamed, unzoomed image with with pixel [0,0] of the
image placed at position [0,0] on the image display.)
- CALLING SEQUENCE
UNZoom_XY, Xtv,Ytv,Xim,Yim, [ OFFSET =, ZOOM = ]
- INPUTS
XTV - Scalar or vector giving X position(s) as read on the image
display (e.g. with Cursor, Xtv, Ytv,/DEVICE)
YTV - Scalar or vector giving Y position(s) on the image display.
If only 2 parameters are supplied then XTV and YTV will be modified
on output to contain the image array coordinates.
- OPTIONAL KEYWORD INPUT
OFFSET - 2 element vector giving the location of the image pixel [0,0]
on the window display. OFFSET can be positive (e.g if the
image is centered in a larger window) or negative (e.g. if the
only the central region of an image much larger than the window
is being displayed.
Default value is [0,0], or no offset.
ZOOM - scalar giving the ratio of the size on the image display to the
original data size. There is no capability for separate X
and Y zoom. Default = 1.
- OUTPUTS
XIM,YIM - X and Y coordinates of the image corresponding to the
cursor position on the image display.
- COMMON BLOCKS
If present, ZOOM_XY will use the TV and IMAGE common blocks which are
defined in the MOUSSE software system (see
http://archive.stsci.edu/uit/analysis.html) If the user is not using
the MOUSSE software (which keeps track of the offset and zoom in each
window) then the common blocks are ignored.
- NOTES
The integer value of a pixel is assumed to refer to the *center*
of a pixel.
- REVISON HISTORY
Adapted from MOUSSE procedure W. Landsman March 1996
Proper handling of offset option S. Ott/W. Landsman May 2000
Put back common blocks for MOUSSE compatibility September 2004
Fix algorithm for non-unity ZOOM values Aug. 2013