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tran stsdas.analysis.dither


NAME · USAGE · PARAMETERS · DESCRIPTION · EXAMPLES · TIMINGS
SEE_ALSO

NAME

tran v0.11 -- Transform am X,Y position from an input to output frame

USAGE

tran origimage drizimage direction x y

PARAMETERS

origimage = "" [file name]
The name of the original input image, before it is drizzled. This string must match exactly with what is written into the header of the output image by drizzle as this is used as a key to find the other drizzling parameters from the output image header.
drizimage = "" [file name]
The name of the image which resulted from drizzling "origimage".
direction = "forward|backward" [string]
The direction of the transformation, either forward from the input image onto the output drizzled one, or backward in the other direction.
x = 100.[float]
The X pixel position on the input or output image which is to be tranformed. If direction=forward then the position is on the input image and if direction=backward it is on the output drizzled image.
y = 100.[float]
The Y pixel position on the input or output image which is to be tranformed. If direction=forward then the position is on the input image and if direction=backward it is on the output drizzled image.
(xylist = "") [file name]
A free-format list of X,Y positions to be transformed. Each line of this file must have just an X and Y pixel position value, separated by white-space. If a file is specified the values of x and y are ignored.

DESCRIPTION

This task transforms an X,Y pixel position between an input image and the result of drizzling that input. It assumes that the drizzling was done using standard drizzle tools and that the parameters defining the mapping from input to output position can be found in the header of the output image. It is necessary that the coefficients files used in the processing (matching their names in the drizzled image header) are available to define the non-linear part of the distortion.

Care must be taken to make sure that the origimage name matches exactly with the string found in the drizimage header.

This task is a wrapper for traxy and tranback which off more flexible image pixel mapping facilities.

EXAMPLES

Let us assume that the WFPC2 image u40x0102m_c0h.fits has been drizzled
onto an image called f555w_1.fits and we want to find where the lower-left
(1,1) pixel of the PC (chip 1 = [sci,1]) ended up:

--> tran u40x0102m_c0h.fits[sci,1] f555w_1.fits forward 1 1
Running Tran Version  0.11 (May 2004)
-Reading drizzle keywords from header...
-Image  u40x0102m_c0h.fits[sci,1]  was # 1
-to be drizzled onto output  f555w_1.fits
-Transforming position...
 Xin,Yin:      1.00000     1.00000 Xout,Yout:   2486.90673  2444.48991

and we can then check the reverse operation as follows:

--> tran u40x0102m_c0h.fits[sci,1] f555w_1.fits backward 2486.90673  2444.48991
Running Tran Version  0.11 (May 2004)
+ TRAN.B V0.2 (November 2003)
-Reading drizzle keywords from header...
-Image  u40x0102m_c0h.fits[sci,1]  was # 1
-to be drizzled onto output  f555w_1.fits
-Transforming position...
 Xin,Yin:      1.00000     1.00000 Xout,Yout:   2486.90673  2444.48991

TIMINGS

It is, as one would expect, very quick!

SEE ALSO

drizzle, blot, traxy, tranback, wtraxy, wtranback, wcs2dr


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